Resize a STL File For Me

[bostonman]

I am in need of a rotary knob with a 6mm D shaft.

I found one on Thingiverse, however, the diameter and height is too big. To confirm whether the style was correct, earlier I printed the one in the attached file, and, as expected, it's too large (it covers writing on the front panel).

My slicing software allows me to scale it, however, it also scales the D shaft hole.

Attached is the zip file from Thingiverse.

Does anyone have software that will scale it without affecting the center shaft hole size?

It needs to be approx. 13mm height, 18mm diameter at the inside end, 17mm at the outside end, and the inside needs to be 3.15mm hollow before the D part of the hole starts (if this makes sense).

Trying to tweak the hole for the shaft may not be feasible, but thought to throw out that size too.

This knob is for an adjustable power supply. The knob broke and was thrown out by someone. If the knob is too large in diameter, it covers writing on the front panel. If the shaft is too deep, then the button can't be pressed (it rotates and also has a on/off press function). I thought to try making one myself on SketchUp, but I wouldn't know how to create the side notches.

[Jeroen3]

Editing STL with many faces like this is complicated. If you can't scale it in the slicer (eg: prusaslicer can scale on separate axis) then you may be better of searching for a parametric knob.

eg:
https://www.printables.com/model/708831-rotary-encoder-knob-and-button-parametric
https://www.printables.com/model/278448-fully-parametric-knob-freecad
https://www.printables.com/model/281352-parametric-lcd-knob

Or maybe there are some Blender wizards here on the forum?

[bostonman]

I assumed scaling it would be difficult. If not for the hollow d shaft, I could have scaled this easier.

Maybe the links you provided have the correct size; let me check later.

[themadhippy]

I thought to try making one myself on SketchUp, but I wouldn't know how to create the side notches.

sketch up tends to get  things reversed,something to with it modeling faces,not a solid object.On shape is my weapon of choice ,although tinker cad might be an easier option.What id do is double check the d slot size,re scale the model  and then make the d slot the size you want.

[bostonman]

Unfortunately I don't exactly have access to a system that allows newer software to work. My old computer still runs XP (long story, but I have lots of expensive software that is costly to update onto a new system and is too old to use with modern revisions of the software), my other is a 32-bit laptop that runs Ubuntu, and normally I use my work laptop that blocks installing software and/or using online sites such as 3D modeling.

The one I've used is SketchUp online (works with Ubuntu 32-bit), and I think it is horrible, however, it has allowed me to make a few designs. Sadly, errors don't show until I generate a STL file and place it in slicing software. At that point blank areas show and will make me realize lots of time was wasted.

If not for the lines on the side of the knob, and wanting it tapered (although I can live with it being cylindrical), I'd design it myself in SketchUp.

[themadhippy]

this any use as a starting point,no d slot yet as i dont have the dimensions and didnt want to assume.

[bostonman]

It needs to be approx. 13mm height, 18mm diameter at the inside end, 17mm at the outside end, and the inside needs to be 3.15mm hollow before the D part of the hole starts (if this makes sense).

I included the dimensions in my initial message. It doesn't need a line indicator as this knob just spins 360 degrees with the readout on the display.

With the little 3D stuff I've done, I'm curious how one does the lines (?) on the side of the knob. My thought was inserting half circles one at a time, but it seemed to time consuming to be the correct answer.

[themadhippy]

I included the dimensions in my initial message

but not that of the d shaped cut out,1 size dont fit all.

, I'm curious how one does the lines (?) on the side of the knob

one my model i drew the base shape  ,then the top circle and used the loft command.That was in onshape.

[Ian.M]

These measurements taken from the O.P's original STL, imported at unit 1mm,  may help:

Code: [Select]

stl_h=15.0; // orig. height
stl_d1=22.1; // orig. top dia. (ignoring rounded top edge)
stl_d2=24.6; // orig. base dia.
stl_fr_h=7.0; // orig. inner cone height (to D shaft)
stl_fr_d1=6.13; // orig. inner cone top dia. (at D shaft)
stl_fr_d2=20.2; // orig. inner cone base dia.
stl_shaft_d=stl_fr_d1; // orig D shaft dia
stl_shaft_l=7.15; // orig D shaft length, from cone top
stl_shaft_f=4.8; // orig D shaft thickness at flat
The knob was rotated flat, wide end down before measuring, and was found to be off-center by approx. 0.06mm in X and 0.03mm in Y.

N.B. the O.P. *will* need to tweak the D shaft diameter and thickness at flat for a good fit, as 3D printer's slicer parameters are rarely tuned well enough to produce accurate holes at nominal diameter, without shrinkage.  Its *HARD* to tune the slicer for accurate holes as the shrinkage varies significantly with inner wall curvature, layer height and flow, and filament used.

[Kean]

If I import that model into F360, it is huge - nearly 250mm diameter.  Stupid imperial units...

What I would do is to import it into a 3D modelling tool (Fusion 360 typically), convert to a solid model, scale it to required size, add a central axis, and then make an extruded cut sized to the D shaft.  If I was enlarging it, I'd add extra material.

Even better, I would contact the original designer to ask if they have the original 3D CAD file.  Working with STL files, even if converted to a solid model, is an awful experience.

Anyway, I did basically what I described above.  Scaled all to a ratio of 18/250, then measured height at 10.2mm so I scaled in just the Y direction to a ratio of 13/10.2.   Draw a bounding circle to get an approximate centre, and then drew the D shaft hole.  I sized that for a 6.35mm shaft, with the D based on the same ratio as the original.  Not sure if that is correct for you, but see attached - should be a quick print to test.

[MarkF]

Okay
Took a little to cut the scallops.
Not sure of the D-shaft dimensions.



D-cut is 6mm dia with a 3mm wide flat

Edit:  Updated shaft size.  (approx 3.3mm flat)

[Kean]

With the little 3D stuff I've done, I'm curious how one does the lines (?) on the side of the knob. My thought was inserting half circles one at a time, but it seemed to time consuming to be the correct answer.

Depends on the 3D modelling tool, but in Solidworks or F360 you would draw one of the scallops and then do a circular pattern to repeat it.

[MarkF]

I used FreeCAD to make a smooth knob (blue) and then created an array of half cylinders (pink).
Finally cut the knob body with the array body.

[bostonman]

Even better, I would contact the original designer to ask if they have the original 3D CAD file.  Working with STL files, even if converted to a solid model, is an awful experience.

I tried this already, but the person didn't respond.

You're correct, I forgot to include the shaft dimension. It's a 6mm D shaft.

I can take pictures of the good knob tonight and post it.

[MarkF]

I updated previous knob002.zip with new shaft size based on a Google search.

[bostonman]

Just an FYI, I've searched many sites for this knob. In a parallel method, I contacted the power supply company (located in China). They can sell replacement parts, however, shipping will be $50 (not including the cost for the parts), so I resorted to searching Thingiverse for a 3D model.

This knob appears to be a custom design/size as most knobs this small are a different shape, have an indicator line, etc...

[themadhippy]

6x4.5D cutout added

[bostonman]

Wow..... thanks.

I don't have the ability to look (or print) it now, but I'll look tonight and try printing this weekend.

The experimental oversized one I printed wasn't very tight on the shaft. Most likely it's my printer, and I can get around this by placing some glue on it. Worst case, if I ever need to remove it, I'll need to cut it, but replacing the rotary encoder isn't difficult. If it gets to the point the knobs need to be removed, then it would mean something is wrong anyway.

Also, another option is I can just scale this model (assuming it works) by an extremely small percentage to reduce the shaft hole.

[themadhippy]

forget my last post,heres the correct version

[Ian.M]

@bostonman

I have managed to rescale your original knob STL using OpenSCAD, filling it in then recutting the interior features to size.   Probably the ugliest part was deriving parameters for the original knob, which was done experimentally and iteratively.

To improve it I'd need actual shaft length from panel (less clearance under knob), actual thickness on flat of D shaft, and desired shaft hole clearance.

Hopefully your laptop has a recent enough Debian to allow you to install OpenSCAD by:

Code: [Select]

sudo apt-get install openscadso you can easily tweak the shaft (and other knob) parameters yourself.

OpenSCAD is basically CAD for programmers.  Here's the script, in all its uglyness:

Code: [Select]

// Fixing up a STL file for EEVblog u:bostonman
// ref: [url]https://www.eevblog.com/forum/3d-printing/resize-a-stl-file-for-me/[/url]

/* [New Knob] */
knob_h=13;
knob_d=18;
shaft_d=6.0;
shaft_f=4.8; // ***best guess***
shaft_l=12; //from knob base, ***best guess***
recess_d1=shaft_d; // recess top dia - make bigger than shaft if flat step wanted
recess_d2=14; // recess base dia
recess_h=3.15;

/* [rendering] */
fill_overlap=0.05; // to guarantee solid
slop=0.1; // increase critical hole diameters by this to print to size
$dd=1e-3; // tolerance for face alignment
$fn=120; // circle rendering facets

/* [Orig. STL] */
stl_h=15.0; // orig. height
stl_d1=22.1; // orig. top dia. (ignoring rounded top edge)
stl_d2=24.6; // orig. base dia.
stl_fr_h=7.0; // orig. inner cone height
stl_fr_d1=6.13; // orig. inner cone top dia. (at D shaft)
stl_fr_d2=20.2; // orig. inner cone base dia.
stl_shaft_d=stl_fr_d1; // orig D shaft dia
stl_shaft_l=7.15; // orig D shaft length, from cone top
stl_shaft_f=4.8; // orig D shaft thickness at flat

// //tweak parametrics to fit the origanal knob
//# cylinder(h=stl_h, d1=stl_d1, d2=stl_d2); // bounding conical frustrum
//# translate([0,0,stl_h-stl_fr_h]) cylinder(h=stl_fr_h,d1=stl_fr_d1,d2=stl_fr_d2); //inner cone
//#translate([0,0,stl_h-stl_fr_h-stl_shaft_l]) dshaft(stl_shaft_l,stl_shaft_d,stl_shaft_f); // d shaft

module dshaft(l,d,f){ //l=length, d=dia, f=thickness at flat
    intersection(){
        cylinder(h=l,d=d);
        translate([0,f-d,l/2]) cube([d,d,l],center=true);
    }
}

module knob_shell(h,d){
    scale([d/stl_d2,d/stl_d2,h/stl_h]){
        translate([0.06,0.03,0]) // it was off-center!
            rotate([90,0,0])
            import("Knob_D_shape_rotary_encoder.stl", convexity=3);
        translate([0,0,stl_h-stl_fr_h-stl_shaft_l-fill_overlap])
            cylinder(h=stl_fr_h+stl_shaft_l+fill_overlap,d1=stl_fr_d1+2*fill_overlap,d2=stl_fr_d2+2*fill_overlap); // infill
    }
}

// render the resized knob
//render()  // only needed (for preview) if graphics driver OpenGL is broken!
difference(){
    knob_shell(knob_h,knob_d); // main object
    // --- cuts ---
    translate([0,0,knob_h-recess_h+$dd])
            cylinder(h=recess_h+$dd, d1=recess_d1, d2=recess_d2); // cone
    translate([0,0,knob_h-shaft_l+$dd])
        dshaft(shaft_l+$dd,shaft_d+slop,shaft_f+slop*shaft_f/shaft_d);
}
[code]

[bostonman]

forget my last post,heres the correct version

I looked at the design and it looks great. I'll try printing it along with the modified one Ian.M posted and see which one is ideal.

Attached is a picture of the good knob.

Update: I'm guessing the 'V' shape hole is a way of getting it to lock onto the shaft. As previously mentioned, I don't really care about this as I'll just glue it. Seeing as how difficult it's been to locate a similar knob, I'm just happy to (hopefully) have a replacement.

[MarkF]

Not exact.   Close.

[bostonman]

I only printed knobd2 so far. It’s basically a perfect diameter, height, etc… but doesn’t fit on the shaft.

If anything, the diameter is slightly smaller, so the X-Y ratio can be increased at my end in the slicing software; maybe by 0.5%. This would benefit the shaft hole.

I’ll work on printing the others this weekend. As for knobd2, besides the shaft hole, the lines on the side could be deeper. This may all be due to my printer having poor resolution, but attached is a comparison.

[Ian.M]

Do you have a micrometer, digital or Vernier callipers or other means of measuring small objects accurately? If so it would be worth measuring the shaft diameter, and thickness on the flat before printing more knobs and posting the results here.  Once we have that, we can easily generate a shaft test jig for you, with an array of D holes matching the shaft geometry, but varying from nominal size in steps of 0.05 mm.  It doesn't have to be very thick or large so should be quick to print, though to avoid inaccuracy due to 'elephant's foot' distortion of initial layers, it would be best printed on a raft.  Fit that to the shaft and tell us which over or undersize fits best, and those of us who have contributed models for you can  resize the D hole to best fit your shaft as printed on your printer.

Also, the shaft length measured from the panel, fully  pushed in (i.e. 'click' switch active) would be useful, though that dimension is less critical.

[bostonman]

I am measuring with calipers, but, to provide (more) accurate measurements, maybe I should wait for the rotary encoder samples to arrive (Ian.M, I believe you’re part of my other post regarding rotary encoders for my broken power supply) to find out if those will fit and replace the originals. From there, the datasheet will provide accurate measurements eliminating any error on my past.. edit: “part” (typing on my phone and auto correct messed up)

The knob that’s too large was suppose to be a 6mm D shaft (what I searched for and the description stated), and that fit (loosely), so my measurements SHOULD be accurate, but maybe mine are slightly off or my printer has poor resolution. (Anet A8).

Also, when I measured mine, it was 6mm give or take. When I looked online, they came in either 6mm or (I believe) 6.35mm. At that point it was too small to be 6.35 and too large to be anything smaller.

[Psi]

If you can convert this STL to a STP/STEP file, and have Altium you can do it by just making a new PCB, placing the STP file 3D body on the PCB at whatever size you want, then export the entire PCB as a new STL file.   Resize complete.

Not exactly a clean way to do it, but should work fine.


Failing that, FreeCAD will do what you want, but can be a bit hard to use if you've never used CAD before.
Maybe if you can find an online video showing how to resize a model in FreeCAD you can get something exported that fits your needs.

[MarkF]

I am measuring with calipers, but, to provide (more) accurate measurements, maybe I should wait for the rotary encoder samples to arrive (Ian.M, I believe you’re part of my other post regarding rotary encoders for my broken power supply) to find out if those will fit and replace the originals. From there, the datasheet will provide accurate measurements eliminating any error on my past.. edit: “part” (typing on my phone and auto correct messed up)

The knob that’s too large was suppose to be a 6mm D shaft (what I searched for and the description stated), and that fit (loosely), so my measurements SHOULD be accurate, but maybe mine are slightly off or my printer has poor resolution. (Anet A8).

Also, when I measured mine, it was 6mm give or take. When I looked online, they came in either 6mm or (I believe) 6.35mm. At that point it was too small to be 6.35 and too large to be anything smaller.

I found a site had a 6mm D-shaft dimensions:
Plus, it's an easy way to measure a shaft with calipers.



You might also what to check the calibration of your 3D printer.  I taped a pin onto my extruder and then laying a ruler on the print bed along each axis measured how far the extruder moves.  Then storing the printer steps/mm for that axis.  For example, set the extruder in one corner of the bed, align the ruler zero at the pin, tell the printer to move 200mm, measure the distance traveled, calculate and store a steps/mm adjustment value if the distances don't match.  Repeat for all three axis.

[themadhippy]

slightly tweaked ,reduced the number of side slots ,made em deeper and made the D slot a smidge bigger.

I found a site had a 6mm D-shaft dimensions:

a rough  guesstimates  the flat length around 3 an a bit mm,which is different to the 6mm rotary encoder shaft i measure ,that had a flat length of 4.5mm

[MarkF]

Really close to the pictured knob.
Finally got my head in gear and figured out how to cut the side grooves and added the domed top.




My D-Slot dimensions (I can make them anything you want):




For completeness, here is the profile:
This is revolved 360deg around the z-axis.




Edit:  Adjusted D-Slot size

[Infraviolet]

bostonman: a tip for you, look for the exe file installer for an old offline Sketchup version, version 7 or 8, from when Google owned it before the sale to Trimble. These will work under Wine on Linux.

Here's some mroe detail:
https://www.dedoimedo.com/computers/google-sketchup.html

If you install blender then you can import a downloaded stl in to blender, export from blender as a dae (collada), Sketchup 7 or 8 will import that dae, then you modify the mesh geometry in sketchup, and re-export to get it to blender, then export a new stl from blender.

[MarkF]

It's much easier to just re-draw these simple parts instead of struggling to re-scale a
STL that doesn't match the part you're trying to replace. 

I'm using the newest version of FreeCAD 0.21.2, which only runs on a 64-bit operation system.

However, you can download FreeCAD 0.18.4 which will run on Windows XP. 
There have been a lot of improvements and features that were fixed.
The learning curve is pretty steep but there are a bunch of videos to help get started.

• https://www.youtube.com/playlist?list=PL7eiW2bt21YU6QEbly78kUgQCNEiDUwSH
• https://www.youtube.com/playlist?list=PL6fZ68Cq3L8k0JhxnIVjZQN26cn9idJrj

[MarkF]

You might also what to check the calibration of your 3D printer.  I taped a pin onto my extruder and then laying a ruler on the print bed along each axis measured how far the extruder moves.  Then storing the printer steps/mm for that axis.  For example, set the extruder in one corner of the bed, align the ruler zero at the pin, tell the printer to move 200mm, measure the distance traveled, calculate and store a steps/mm adjustment value if the distances don't match.  Repeat for all three axis.

While you're doing the calibration, don't forget to do the extruder.  I load in a light color filament, measure off 110mm of filament from where it enters the extruder and mark the filament with a Sharpie.  Then, extrude 100mm of filament.  Measure the filament again that you have the 10mm left.  Store a correction into the printer if it didn't extrude the 100mm you told it to.

Repeat all your measurements until the printer moves the exact distances you tell it.  Obviously, the larger distance you can measure, the more accurate your calibration will be (i.e. Measuring 300mm would be better than measuring 10mm.  A 1mm error in measurement would have a lower impact if doing the 300mm distance.)

[bostonman]

Mark F, I downloaded Knob002-ver4 and opened the slicing software. I'll print this today, however, looking at it in the slicing software, it looks like additional shapes will be printed giving it the appearance it may not be smooth (see attached) - it looks blurry ironically. Maybe it's just how the slicing software is interpreting it, and the print will be fine.

It doesn't take long to print, so running these prints to test size and stuff isn't an issue anyway.

On another note, I was unaware my printer needs and/or could be calibrated. I'm uncertain who has experience with an Anet A8, it's a good printer, but my experience is that it's sloppy in many directions due to the nature of the printer. Many upgrades exist which I've printed and added, but I thought it was more about belt tension as most prints improved once I added braces and tightened the belts.

This is good feedback and I'll certainly look into checking the calibration.

[MarkF]

I see what you mean about the look of the smoothness.  I expect it's just the mesh on the curved areas and the knob being so small.  I haven't printed it so I don't know how smooth it will be.  Try printing with a small layer height (maybe 0.12mm)


I can't find the original video I watched but here is one showing the process.
A few notes:

• You will need to find the similar menus for your printer.
• I don't like the extruder process which requires taking the printer apart.  That's why I say heat the hotend to 200^oC, mark off 110mm of filament from where it enters the printer, extrude 100mm and measure filament to where you marked it.
• Out of the box, I had to make some minor adjustments to get my prints dimensionally correct.  At least within a few thousandth.  We are talking small corrections here.  But when you're fitting parts together, these differences matter.

[bostonman]

I printed it before your reply.

It seems to have printed fine. The side grooves aren’t too deep, but I suspect that’s my printer. Sadly, it still doesn’t fit on the shaft; which again may just be my printer. Even applying lots of force, enough to damage the new encoder switch, it won’t slide on.

I’ll have to look into the calibration when I get a chance this week before I print another.

[MarkF]

Deeper grooves..
You said earlier that the Thingiverse knob fit loosely? 
I matched up the hole size to the Thingiverse knob.
(It's now 6.1mm with 4.7mm slot)

[Ian.M]

I wouldn't be surprised if the X and Y axes are off a mm or so in 100, so calibration will certainly be beneficial, but I would be very surprised if its off by a large enough percentage to affect the fit of a 6mm hole.  X and Y calibration on Prusa I3 clones like the Anet A8 is affected by belt tension, as they do stretch slightly under tension, so make sure the belts are tensioned correctly before calibration.

Extruder calibration is likely to improve small hole fit some, but the volume extruded is also critically dependent on filament diameter, and cheap filament may deviate significantly from nominal. e.g. 1.72mm instead of nom. 1.75mm is 3.4% less volume per unit length.    Take several measurements of the filament diameter for each new spool, and update your slicer's filament settings accordingly.   Even so, you will have to adjust small holes to compensate for the line being extruded dragging inwards as the nozzle moves round small radius interior perimeters, hence my suggestion to print an array of different fit holes test jig to see which hole fits best.  N.B. if you alter the perimeter extrusion speed or nozzle temperature, the required hole compensation will change some, so keep them consistent between test jig and actual part.

Also note that the as-shipped Anet A8 firmware is notorious for not having thermal runaway protection enabled, so unless you have upgraded to a version of Marlin compiled with thermal runaway protection enabled, *DO* *NOT* print unattended, even for only a few minutes.

[bostonman]

I’ll try printing it tonight or tomorrow.

Yes, the Thingiverse was loose, but it’s fine as I planned to glue it. The original knob (as you probably saw) uses a V shape groove which I assume causes it to grip tighter on the shaft. Maybe the corners make a solid contact and the flatter part has less contact resistance allowing it to slide on easier and that’s how it manages to have such a strong hold without needing to force it.

Whatever the case may be, the fact a replacement knob now exists is absolutely amazing. Years ago we couldn’t do this, now someone at one part of the world can send a file to someone else and have a replacement part for the cost of a few cents in filament.

[MarkF]

I overlayed mine with the Thingiverse knob and mine is ever so slightly smaller.
If your new print is too loose, I shave a little more off to make it tighter.
The last (ver6) is a 6.1mm diameter.  I could make it 6.05mm.  Let me know.



Mine = gray
Thingiverse = purple

[Ian.M]

Another idea might be to adjust the size to slightly too loose then add a few narrow thin ribs on the interior flat of the D, along the shaft not cross-wise to add some crushability for a snug fit.

[bostonman]

Also note that the as-shipped Anet A8 firmware is notorious for not having thermal runaway protection enabled, so unless you have upgraded to a version of Marlin compiled with thermal runaway protection enabled, *DO* *NOT* print unattended, even for only a few minutes.

Fully aware of this issue and appreciate the warning. The printer has been upgraded with the MOSFET for both the extruder (not necessarily needed) and the bed along with Marlin firmware. My goal was to add the Btouch (?) sensor, for auto leveling, but never got around to installing it.

Okay, here is the latest, something is odd. First off, keep in mind, I'm waiting on replacement rotary encoders that may or may not be the correct replacement due to size or whatever. With this being said, I'll gladly hold off trying to get a 3D printed knob that fits until these new encoders arrive.

With this being said, the most recent one still doesn't fit. I measured the encoder shaft, it's 5.98mm (I'm seeing 5.95mm at a few points - most likely worn down from removing the knob many times) and 4.48mm flat side to round part.

The Thingiverse part I printed (i.e. oversized knob) is approximately 6mm and fits tight enough that I can hold it upside down without it sliding off, but, if I hit the board on my hand, the knob falls off. The most recent one I printed from you is measuring approx. 5.44mm (and that's pulling on the calipers extremely tight).

Maybe something has shifted with my printer since I printed the Thingiverse one (because that fits and measures 6mm). Measuring the rest of the knob recently printed: base 18.25mm, top 17mm (hard to get a good measurement because it's rounded, height 13.05mm.

Give me a minute and I'll post a picture of the D hole being measured.

Edit: I also added a picture of the oversized Thingiverse hole size showing it's basically 6mm.

[MarkF]

You got me now.
Somewhere you said our knobs were a little smaller than the original.
So, I increased the knob overall diameter.  The base diameter should be 18.4mm

With an overall printing error of 0.15mm, you D-slot diameter should be 6.1mm - 1.5mm = 5.95
But, you show 5.44mm

Here is a 6.25mm diameter slot.
The base is still 18.4mm.

What size would you like me to make it?

[bostonman]

I haven't tried your latest version, however, I went into SketchUp (online) and created a 3mm radius circle (should be 6mm diameter - unless I or SketchUp mesed up).

In the slicing software, I put your Knob002-ver6.zip (which has a file name: Knob002 inside) next to the 6mm circle (see attached) - I also scaled it up to 200% for better resolution.

The outside oval is the skirt (ignore), the left is your knob, and the right is the 6mm circle. With my limited tools (or at the moment mentally drawing a blank on another method), I went into Photoshop, drew a thin rectangle around the 6mm (outside of the three yellow lines) to use for measuring, dragged it over, and compared the two.

It looks like the hole on the knob is 6mm because the rectangle fit in the hole (I thought maybe my slicing software wasn't interpreting the stl file correctly). Is it possible where I drew the red arrow that the radius is closing too soon causing the shaft to not fit in?

Ignore my statement and the red arrow as it appears the measurements you show in your 2D drawing match throwing my theory out the window.

I'm measuring the base and seeing around 18.25. The diameter changes as I spin it down to around 18.11mm, but believe this is due to catching the lines. Although the diameter changes, it doesn't seem that it printed oval implying one of the axis has a loose belt. In all cases, I'm not seeing close to 18.4.

I will still look into calibration and belt tension, but something is obviously off. Maybe printing it at 90% fill is causing issues or printing in the cold (it's in my basement) is causing issues.

[Ian.M]

Scaling off the original STL, as rendered by OpenSCAD, I got dimensions of 6.13mm dia, and 4.8mm  on the flat. but that's before printing, and as I explained above, unless the slicer software is advanced and very well tuned, FDM 3D printed small holes invariably close up some when printed.  It seems likely that a 6.13 mm hole was printing 0.13mm or so undersize and it felt loose because that wasn't enough to bring the D flat dimension down to the 4.5mm or so that would be needed for a slip fit to the existing shaft.

However you can get a false tight fit due to Z banding resulting in a hole that's snakey rather than straight sided, and as its got a flat, reaming to size is not a practical option.   

Try this test jig for fit on your existing measured shaft, preferably printed on a raft to avoid elephant's foot distortion.  It starts off at exact nominal size for the hole at the notched corner, and goes up in 0.1mm increments along its length.  The second row holes are 0.05mm bigger than the adjacent first row hole.  The max. oversize is +0.55mm, and if that's not enough, you probably need to fix/tune your printer!

Code: [Select]

shaft_d=5.98;
shaft_f=4.48;
h=3;
grid=10;
nx=2;
ny=6;
ovstep=0.05;
$fn=120;
$dd=1e-3;

module dshaft(l,d,f){ //l=length, d=dia, f=thickness at flat
    intersection(){
        cylinder(h=l,d=d);
        translate([0,f-d,l/2]) cube([d,d,l],center=true);
    }
}

//render()  // only needed (for preview) if graphics driver OpenGL is broken!
difference(){
    cube([grid*nx,grid*ny,h]);
    // --- cuts ---
    cylinder(h=h,r=1); // mark origin corner
    for(x=[0,nx-1])
        for(y=[0:ny-1]){
            oversize=ovstep*(y*nx+x);
            echo(str("[",x,", ",y,"] +",oversize," mm"));
            translate([grid*x+grid/2,grid*y+grid/2,-$dd])
                dshaft(h+2*$dd,shaft_d+oversize,shaft_f+oversize*shaft_f/shaft_d);
        }
}


[MarkF]

I don't see how the outside diameter is off by 0.15mm while the inside slot diameter is off by 0.5mm.  Over extrusion might cause some of that.  But not that much difference.

Until you do a calibration, you might try printing a 100mm x 100mm square that is only 2 or 3 layers.  Leaving a 50mm x 50mm hole in the middle.  See how close the measurements are.

[MarkF]

Looking again at the knob print you did; are those ridges, highlighted in red, layer shifts?
They are going to have a hugh impact on the size.

[bostonman]

I will print the test jig tomorrow; it's a great idea.

As loosely mentioned, I'm taking all the possibilities into account and will exercise calibration, belt tension, etc... For now, I just tinkered with the STL file for fun.

Sometimes I like to rule out the simpler things and/or just putts around with what is somewhat easier to rule out; in this case it was easy since I was sitting in front of the computer.

Ian.M, as usual, your input is very well accepted. It's quite obvious it's printer related, whether one or a combination of stuff you (and others) have mentioned.

Scaling off the original STL, as rendered by OpenSCAD, I got dimensions of 6.13mm dia, and 4.8mm

Just to clarify, are you referring to the initial one I posted that's too large (30mm ??) If so, then it would explain why it fit (and loosely) since these others were drawn at 6mm.

Does it make sense to make the hole as a V shape per the factory knob? As I mentioned, I'm guessing the V part allows for less of the surfaces to touch giving more room for error whereas a (half) hole has to fit a round shaft.

My printer isn't anything great as some of you may know. How I acquired it is a different story, but I printed many of the associated brackets allowing me to tighten the belts without bending the acrylic (or less bending). The shaft bearings were replaced for smoother movement, belts were tightened (may have stretched now), and I built an overhead filament holder reducing friction as the roll turns.

[bostonman]

Here are some closeups. It’s printed so the closed end is the bottom layer and I’ve noticed the printer doesn’t handle curves well, so the first layer is part of the support material and the curved part is a bit off. The sides are fairly smooth with the ability to feel the layers as I pass my fingernail across them.

[MarkF]

Another thing you can try is design a small cylinder with a 6mm hole in SketchUp.
You'll want to verify the inside and outside are smooth to rule out loose belts.
Adjust the size till you get a fit.  We can then adjust the knob in the short term.

[MarkF]

Here are some closeups. It’s printed so the closed end is the bottom layer and I’ve noticed the printer doesn’t handle curves well, so the first layer is part of the support material and the curved part is a bit off. The sides are fairly smooth with the ability to feel the layers as I pass my fingernail across them.

Are you printing it upside down?

You might try right-side up with supports.
Maybe the print is rocking on the dome as it prints.

With a 0.12mm layer height, the print should be extremely smooth.
Not what's in the pictures.

[bostonman]

I'll try printing it the other way too.

Thought having less support material was better, so I flipped it.

[MarkF]

Overall, it sounds like you should really do the printer calibration and give it a good look-over for anything loose.
Especially since you've made a bunch of modifications and updated Marlin (correct?).
You should be able to do everything through the printer control panel.

I just changed a wore out brass extruder gear to a stainless steel one on my CR-10 today. 
That alone changed my eSteps for the stepper motor from 97 to 100.5.

[bostonman]

Overall, it sounds like you should really do the printer calibration and give it a good look-over for anything loose.
Especially since you've made a bunch of modifications and updated Marlin (correct?).
You should be able to do everything through the printer control panel.

Yes, Marlin and a bunch of modifications have been done. The belt tension upgrades could be implemented, but I never got around to it and always questioned their strength. I got the tension fairly tight and it seemed to make a tremendous improvement (but they may have stretched).

Eventually I found myself spending more time upgrading than actually using it; so I began accepting the prints as they were.

Most stuff I've printed wasn't dependent on such resolution, now I'm in uncharted territory. The printer has never been calibrated as I was unaware this was needed. The only calibration was trying my best to get the Z axis level along with bed leveling.

The test jig is a great idea and may provide just how far off my printer is, so let me provide some updates (hopefully) tomorrow.

[Ian.M]

Scaling off the original STL, as rendered by OpenSCAD, I got dimensions of 6.13mm dia, and 4.8mm

Just to clarify, are you referring to the initial one I posted that's too large (30mm ??) If so, then it would explain why it fit (and loosely) since these others were drawn at 6mm.

Yes, the STL from thingiverse attached to your initial post.

Does it make sense to make the hole as a V shape per the factory knob? As I mentioned, I'm guessing the V part allows for less of the surfaces to touch giving more room for error whereas a (half) hole has to fit a round shaft.

No. That is for a light press fit with injection moulded parts, and will have been carefully optimised for the original plastic used and the wall thickness of the shaft boss adjusted to allow the plastic to flex to make it work.   FDM 3D prints have anisotropic strength, usually far lower than injection moulded parts even with similar plastics, so the feature would need to be redesigned and re-optimised to work effectively without sheering off the shaft boss when it flexes.

Its much easier to simply tweak a D hole to fit reasonably well then figure out how to retain it.  Glue it as you proposed, or maybe a 2.5mm cross hole to allow a M3 grub screw to be tightened on the shaft flat.

My printer isn't anything great as some of you may know. How I acquired it is a different story, but I printed many of the associated brackets allowing me to tighten the belts without bending the acrylic (or less bending). The shaft bearings were replaced for smoother movement, belts were tightened (may have stretched now), and I built an overhead filament holder reducing friction as the roll turns.

Similarly, except my I3 clone has a plywood frame, which was a bit better braced than the Anet design.  I can generally get small parts to come out close enough to what I want.   If in an unheated room in winter, some sort of an enclosure is recommended to block drafts and control warping, which can be as simple as a very large cardboard box with a clear plastic curtain to cover the open front.  Use the Marlin menu to turn on the bed heater (only) to warm up  the enclosure well before staring the print.   If you trust its wiring and MOSFET, use its 90° (ABS) bed preheat setting for faster enclosure warmup.   I tend to do so at least 20 minutes before starting a job, then set the correct bed temperature when I open the slicer and give it 5 minutes or so to stabilise at the new temperature while I'm importing the STL and setting it up to slice and print.

On the subject of calibration jigs, Assuming you can run OpenSCAD, change the line:

Code: [Select]

                dshaft(h+2*$dd,shaft_d+oversize,shaft_f+oversize*shaft_f/shaft_d);to:

Code: [Select]

                cylinder(h=h+2*$dd, d=shaft_d+oversize);for round holes you can check against a gauge pin (or any other smooth round rod of accurately known diameter).  Set shaft_d (first line of script) to the actual diameter of the test pin or rod.

Edit: Another way of getting round holes is to simply set shaft_f (second line) to the same value as shaft_d.

[bostonman]

I didn't see your message until tonight; and I already printed everything.

We've definitely established my printer needs some adjustments, but for the fun of it, I printed a few test items. First off, the test jig results are attached. The bright green were loosely fit (fall off the shaft loose if it was a knob), dark green fit tight but nice and snug (held onto the shaft equal to the factory knob), and red it wouldn't fit at all - notice third from the bottom on the left is a bright green.

I printed a square with a 6mm hole in the middle, using calipers, it measures approximately 5.62mm with some slight variations in all directions. Also printed was a 6mm cylinder (approx 7mm height) and measures 6mm and up to 6.18mm as I spin it (implying one belt is looser than the other - or it wobbled due to it's thin structure).

The latest revision knob was printed, without rotating it in the slicing software (made trying to remove the supporting material fun), one was printed at the default 0.3mm layer height (first layer is 0.35mm by default) and the other 0.12mm layer height.

The hole is measuring around 5.7 and 5.8 on both, but varies (it may be because how the calipers are seated in the hole and/or touching filament residue due to supporting material).

In any case, both knobs fit, it's very (and I emphasize that word) tight fit that requires lots of force, but it does fit. I wouldn't use this much force on the new encoders when I get them, so the holes could be sized slightly larger.

The current knob, with the exception of having to apply lots of force to slide onto the shaft, is perfect. The lines on the side, diameter, height, roundness, etc... are essentially equal to the factory one.

My suggestion is to wait until I get the new encoders to confirm they are the correct size/function and then just enlarge the shaft hole again.

If I mess with the printer belts and calibration, then we'll end up starting over trying to get a hole that will fit the shaft. My suggestion is to leave the printer as is for now, print the knobs with the compensating hole size, and then at some point I'll tinker with the printer.

[Ian.M]

The test jig may be indicating between 0.1 mm and 0.15 mm shrinkage on a 6 mm hole ID.  The red no fits near the notched corner are as expected but the cluster of five snug fits after the first loose fit  are not, so something odd is going on there.

The console log of the echo statements was:

Code: [Select]

ECHO: "[0, 0] +0 mm"
ECHO: "[0, 1] +0.1 mm"
ECHO: "[0, 2] +0.2 mm"
ECHO: "[0, 3] +0.3 mm"
ECHO: "[0, 4] +0.4 mm"
ECHO: "[0, 5] +0.5 mm"
ECHO: "[1, 0] +0.05 mm"
ECHO: "[1, 1] +0.15 mm"
ECHO: "[1, 2] +0.25 mm"
ECHO: "[1, 3] +0.35 mm"
ECHO: "[1, 4] +0.45 mm"
ECHO: "[1, 5] +0.55 mm"
which indicates it calculated the oversize for each hole correctly.  Hole id is [x, y] with [0,0] next to the notched corner.

Its suggestive of printer or environmental problems, possibly warping due to loss of bed adhesion at one end, resulting in 'dogleg' holes at the edge of the area that lifted.

[MarkF]

If you are satisfied with everything else about the knobs except the hole size, you may be better off just having the slicer scale the knob by 101% - 105% for a snug fit.
Whichever you choose, I'm perfectly happy to make any adjustments you want.


One point of interest:
   If your Anet stepper motors and lead screws are like Creality CR-10, each step results in a linear movement of 0.04mm.  For example, choosing a layer height of a multiple of 0.04mm will not require any partial steps.  I always choose layer heights of 0.08mm, 0.12mm, 0.16mm or 0.20mm.  I never go beyond 0.20mm.  That's just a personal choice.  My default is 0.2mm unless I want some fine detail.

[bostonman]

I've never changed any settings except infill and maybe some other basic settings.

Maybe the test jig got slightly warped when I removed it. The bed has painters tape for a base and I struggle to get some items from it. I've seen a rubber (?) sheet that is magnetic allowing it to be removed and making part removal easier, but never invested in it.

At some point I need to learn a bit more about 3D printing along with calibrating this printer since I've never done it. Unfortunately I don't do much printing, and, anything I've printed hasn't been affected by being off by a few millimeters.

This knob has certainly opened my eyes to issues with my printer. At the same time, I'm unaware just how accurate the printer should be making parts. My goal about two-years-ago was to install the belt tension adjustments. They don't strike me as very sturdy, but, either way, I thought having the ability to loosen them when the printer isn't being used would reduce belt stretching.

Another issue I felt was that it has so many upgrades available that I was basically putting three to four times into the printer whereas I could just buy a higher end one; so I began accepting prints as they were.

I never expected this knob design to be so involved. It's a power supply that someone hit, took out one of the two knobs (and encoder shaft) along with three banana jacks. It's not a high end power supply, but it was in the trash bin at work. Being able to bring things back to life for not only my benefit, but keeping them out of a landfill, is a nice felling.

[Ian.M]

My first useful print was a 'bumper' for an Arduino Mega.  It took quite a bit of fine tuning of my CTC DIY I3 to get one that fitted.  Back then I was also printing on painters tape, but switched to printing on glass with hairspray as an adhesion promoter, after I'd got fed up with replacing damaged tape every few prints.   Glass isn't for everyone, as to get a good first layer, the nozzle height must be more accurate over the whole part footprint, and any warping of the part typically results in total  adhesion failure and a failed print rather than just lifting a corner and continuing with some distortion the way printing on the more forgiving painters tape typically goes.  However, if you can cut the glass to size yourself, its a very cheap bed upgrade.   

I also had tensioner problems, as CTC had made some very strange design choices, and the D shaft used for the tensioner pully axles was trying to grind its way through the tensioner bodies, but I noticed the slackening belts in time and buying and installing the ball bearings they'd muntzed out  in the recesses still provided for them fixed that.  I generally leave the belts tensioned, as the plywood frame can take the strain, and simply switch on and move the axes every month so the belts don't take a set, but if I was storing it long term I would slacken them.
With an acrylic frame its less advisable to leave them tensioned as the plastic can warp or fail under sustained load, but as you need consistent tension for good calibration, its a PITA to have to frequently slacken them and retension to the same tightness.

Unless your bed is very flat and accurately levelled, having a BLtouch installed, with its probe as near the nozzle as practical, makes a big difference to larger footprint parts.  However as an Anet A8 typically has an ATMEGA1284P controller, getting Marlin built to fit with bed levelling enabled can be a PITA, as it only has half the memory of an ATmega2560.

[bostonman]

The glass and hairspray technique is something used previously. As a result, I have a piece of glass. The current setup is the metal original bed with the glass on top, and painters tape holding down the glass.

As mentioned, the item I saw about two-years-ago was a rubber (?) flexible sheet. if I remember correctly, a strip of magnetized metal gets taped to the bed, and this sheet sticks to it using magnets. After a print is complete, the entire rubber sheet lifts off and you can peel it away from the print, and then reapply the rubber sheet.

It looked quite useful, but at the time painters tape seemed to do the trick.

My Anet has a front and rear bracket mounted to it preventing (or reducing frame bending). If I remember correctly, the design shows to mount these utilizing the threaded rod, however, I have a piece of wood (clear stained) as a base and screwed the printed brackets into the wood. Also, the threaded rod has four brackets holding them down to the wood base as well. For some reason I remember using t-nuts, but, either way, the printer is mounted quite tight to the wood base (maybe 3/8" wood - not plywood - some sort of quality stuff I think). It even has the brackets for the upper part to reduce wobbling.

Basically my printer can be spun on every axis in the middle of a room and (hopefully) not see a shift in the frame - at least this is the image I have due to the amount of effort I put into making it sturdy.

The big issues are bed leveling (I absolutely agree that the BL Touch is a great improvement - I just never got around to adding it) and belt tension. Otherwise, I've taken into account all the mounting, reduced friction everywhere I could, etc...

I could be wrong, but believe due to the lack of features I care about (open thermistors shut down is the first feature I care about), I'm able to fit the BL Touch and standard features into the amount of memory available - you're correct though - it's awfully close to running out of room.

The personal issue I had was (as mentioned) felt I was dumping more time/money into the printer and using it to test upgrades rather than just buying some $2k unit that wouldn't need any (or much) upgrades.

My plan was to get a new PC, expand my interests on the mechanical side (I've taken on more interests doing 2D drawings and 3D designs), and maybe then upgrade to a new printer. My hurtles are that in order to transfer my extensive amount of software that I "obtained" years back when it was easier to "obtain", I'd need to "buy" updated versions. If I use a virtual XP system (or run two PCs) so I can still use my software, then I use old software that I can't use new files in. An example is say Altium. I can't take a new Altium file and have it open in a decade old version (or maybe I can, but just using an example).

Normally I use my work laptop for stuff and my XP to bang around. It's getting more ridiculous though to work around such issues as I just experienced with this knob where I have very limited options on taking a STL file and tweaking it or working with someone who has a CAD file who can share it so I can tweak it. My work laptop is limited on what I can do since I can't install anything and certain sites are blocked, but my XP is limited for obvious reasons. Also, I just dread new computers. Having to work through 30-day trial software, the quirks, installing codecs, etc... Wish XP would have just remained the OS forever.

[themadhippy]

Have you tried to see if either your older machines,or possible the works machine can accesses the likes of tinkercad (https://www.tinkercad.com ) or onshape (https://www.onshape.com)

My hurtles are that in order to transfer my extensive amount of software that I "obtained" years back when it was easier to "obtain", I'd need to "buy" updated versions.

or leave the old machine alone and use it for those tasks,with the new machine dealing with modern stuff

[bostonman]

I'll try later.

FreeCad (link was suggested in a previous post) didn't work with XP.

Years ago I had two computers aside of each other. One was used for old stuff and other stuff while the new one (current) was the one that would only run software I knew was safe. Eventually it got to the point where the old one took forever to boot and wasn't worth keeping.

Obviously options exist to keep my old system such as what I mentioned, a PC (forgot what those are called) that runs within a virtual window. From experience such as having two PCs is that it becomes not worth it anymore.

The answer really is to get a new PC. I should be posting questions about needing help with making a knob rather than having someone do it for me; or people helping by working around my PC limitations.

[Ian.M]

I printed an encoder knob from my reply #19 OpenSCAD script, for a 5.95mm dia, 4.45mm thick D shaft today.  0.05mm oversize wasn't quite enough on my printer, 0.1mm would have been better choice, but a little work with a very small file to smooth out the slight layer ridges in the hole and it went on well enough.

[MarkF]

Seems to me that you need one of these (Not for gaming):     
   https://store.minisforum.com/collections/all-product/products/minisforum-n40-mini-pc


There are older versions of FreeCAD (version 16 lists WinXP):
Quite old.  Don't know how well it works.
   FreeCAD.0.16.6706.f86a4e4-WIN-x86-installer.exe

Plus there are Linux and Mac versions:
I believe the 0.18.4 is the last of the 32-bit builds.
   https://wiki.freecad.org/Download


Oh.  You might want to determine if the knob 6mm hole is the issue or the distance to the flat.
A round ~6mm hole would determine the hole size and the flat adjusted afterward.

[MarkF]

Well, that was an adventure...

I installed FreeCAD 0.16 on my WinXP computer.

After install goto Edit->Preferences and:

• Select Part Design as your default workbench.
  
• Select navigation style to Touchpad.
  This will allow you to:
     Pan (hold Shift Key, no mouse buttons) moving the mouse
     Rotate (hold Alt Key, no mouse buttons) moving the mouse
     Zoom In/Out with mouse wheel
  

Creating the Knob is a totally different procedure than in the latest FreeCAD version.
Here is the knob using verions FreeCAD 0.16. 
The dimensions may be all wrong.  I did it from memory.


Here are the dimensions for the last non-FreeCAD_0.16 knob:



Edit:  Updated CAD file with latest dimensions.

[Infraviolet]

I note you mention the knob is a bit loose, it's because 3D printed D shaft holes just aren't very good. The plastic is soft enough that in the really small volume of plastic wich experiences all the forces when torques are applied between the D shaft the the attached plastic thing, the force tends to distort the plastic. I'd always recommend trying to insert some nut slots and screw holes so you can use a screw to clamp against the flat side of the shaft.

This video:

shows how a screw and a nut can be used on a D shaft's flat, though if you go in from both sides 180 degrees apart with 2 screws you often do better as one screw has its end clamped against the flat and one has its end clamped against the curved side of the shaft opposite the flat. This should be a fairly simple geometry to integrate in to your knob. You can have the nuts slotted in from the bottom face, so the top one sees will still look smotth. The only visual difference will be two holes, of diameter sufficient for the screw's heads (M2.5 or M3 will do fine for low torque situations) coming in from the sides.

[Ian.M]

If you are going to add a grubscrew, or if you need to add captive nuts in general to 3D printed parts, but don't want to mess with heat-staked inserts, do yourself a favour and use a square nut.   
e.g. https://www.mcmaster.com/97259A101/
Compared to a hex nut, the fit is far less critical, they are far less likely to spin in their hole. and have a greater surface area to transfer end-load to the part.

[bostonman]

I don't have much experience making 3D parts, but for me (and some of you from previous posts know I tend to go overboard), I think utilizing metal in certain applications is beneficial.

In the case of the shaft, make the 3D part so it can hold a metal insert (maybe brass) with a few spline lines (?) internal, drill a hole in the metal, thread it with a die, use two-part epoxy to keep the metal from slipping (the epoxy will go inside the spline lines for extra strength), and now you have a much stronger piece for a set screw.

My other thought is to make a part, if the software allows it, inverse the design so it's a mold, print it, and then use something like JB Weld to fill the mold. Now you have quite the heavy duty part.

Most likely printing with other material makes for much stronger stuff - but I only have experience with PLA.

[MarkF]

It's possible you may want to take the knob off or need to repair the power supply.
If the knob fails or starts coming slipping off, you can always print another or change its dimensions.
Maybe you want to change the color to match your outfit of the day... 

[bostonman]

It's possible you may want to take the knob off or need to repair the power supply.
If the knob fails or starts coming slipping off, you can always print another or change its dimensions.
Maybe you want to change the color to match your outfit of the day... 

Were you referencing my previous message? If so, I was referring to the previous message about using a set screw for the design used in the posted video. In the case of my power supply, the existing design will be fine.

[bostonman]

Well, that was an adventure...

I installed FreeCAD 0.16 on my WinXP computer.

Did you get this error: DLL load failed %1 is not a valid Win32 application

[MarkF]

Well, that was an adventure...

I installed FreeCAD 0.16 on my WinXP computer.

Did you get this error: DLL load failed %1 is not a valid Win32 application

No. I didn't get any errors installing version 0.16.
Are you sure you downloaded the 32-bit version?
I downloaded the x86-installer.

[MarkF]

It also ask to install the Visual Studio libraries. Accept and let it do them

[Ian.M]

Revised knob with grub screw hole and slot for a square nut.  Still based on resizing the original Knob_D_shape_rotary_encoder.stl from the first post.

Apart from some parameters for the nut, it only needs a few lines of code added in the cuts section of the difference().

Code: [Select]

    translate([0,knob_d/4,knob_h-shaft_l/2-recess_h/2])
        rotate([90,0,0])
        cylinder(h=knob_d/2, d=nut_size+slop, center=true); //grub screw
    translate([0, nut_thick/2+nut_to_shaft+shaft_f-shaft_d/2, 3*knob_h/2-shaft_l/2-recess_h/2-nut_af/2-slop/2])
        cube([nut_af+slop,nut_thick+slop,knob_h],center=true);  //nut slot


[bostonman]

No. I didn't get any errors installing version 0.16.
Are you sure you downloaded the 32-bit version?
I downloaded the x86-installer.

Sorry...Realized after I went to bed that I didn't specify the error occurred after installing, when I loaded FreeCad.

The link had several files, and I downloaded them all (maybe 12 or so). From what I could tell, two .exe files existed that both needed to be installed.

I'll have to do more investigating tonight. From what I could tell, it needs or depends on Python and/or VS stuff. I'm guessing something isn't linked correctly or I didn't install some library.

[MarkF]

There is only one file to download and install (direct link to Github 32-bit Windows installer):
   FreeCAD.0.16.6706.f86a4e4-WIN-x86-installer.exe

The other files are for different operating systems, 64-bit Windows, or additional files required for compiling FreeCAD from the source code.  Sure, it uses Python, Qt and Visual Studio dll's under the hood.  But that's not your concern.  I see the 'over achiever' in you extends beyond just hardware.

As you say, there are two .exe files available.  One is for 32-bit Windows installs and the other is for 64-bit Windows installs.  You can't install both.  I see why you got the errors.  It's trying to use 64-bit libraries.  Un-install FreeCAD from the XP control panel and just install the 32-bit exe linked above.

[bostonman]

I see the 'over achiever' in you extends beyond just hardware.

That was funny. Sometimes I'm my own worst enemy.

[bostonman]

I'll need to dig into this more over the weekend, but still no luck.

Edit: I selected <view> <draft> and managed to get a window.

Not sure how this program works, but all, or most, in the "view" drop down menu gives the DLL error (that's the error I was referring to before).

[themadhippy]

Not sure how this program works

Best of luck,i spent sevral weeks trying to get to grips with it,watched countless tutorials,banged my head of the wall,watched more tutorials before deciding brain salad surgery would be simpler.

[MarkF]

I'll need to dig into this more over the weekend, but still no luck.

Edit: I selected <view> <draft> and managed to get a window.

Not sure how this program works, but all, or most, in the "view" drop down menu gives the DLL error (that's the error I was referring to before).

I assume this means you were able to install FreeCAD successfully and are having trouble knowing what to do next?   

I linked to two Youtube channels a while back that have about 50 vidoes on how to use newer versions.  They probably won't get you over the first hump.  So here are some startup screen captures on setup and getting to a useful start place.
(Note.  The 'Draft' workbench is the last place you want to start.  Start on either the 'Part' or "Part Design' workbenches.)

• This is the initial start page after install.
  Goto the Edit->Preferences tab to make viewing your model easier.
  
  
  
• On the 'General'->'General' tab set the Startup to 'Part Design'.  In most cases, the 'Part Design' is going to be the workbench you use most for complex models.
  
  
  
• On the 'Display'->'3D View' tab change the Navigation to 'Touchpad' (even if you don't have a touchpad!!!)
  Panning and rotating the model by pressing either the Shift key or Alt key and moving the mouse WITHOUT pressing any mouse buttons.  Zoom is with the mouse wheel and can be reversed with the 'Invert zoom' on this same tab.
  
  
  
• The next two are optional.
  On the 'General'->'Units' you can select millimeters or Imperial.  I do Imperial because my calibers has an analog dial that is in inches.
  
  
  On the 'Display'->'Sketcher' turn off the 'Show grid'.
  
  
  
• After restarting FreeCAD you will see the 'Part Design' workbench'.  You can change workbenches from the dropdown box at the top.  On this 'Part Design' workbench you will draw a shape on a plane from which you can pad or cut using that shape to make a solid or cut a hole. 
  
  On the left will be two tabs 'Model' and 'Tasks'.  The 'Model' tab will contain a tree view of the shapes you have created.  The 'Tasks' tab you will use while drawing a sketch.  At this point, you first need to create a new empty document, create a sketch and then select which plane you want to draw on.  (Some of the videos will help with the actual drawing.)
  
  
  
• If you open the knob file for FreeCAD version 0.16,  it should look like this. 
  Clicking on an item in the tree 'Labels & Attribures' will allow you to turn that item on/off with the Spacebar, it will also allow you to change its properties in the bottom half,  double clicking will open the item to change it's shape and dimensions, you can also add new sketches to effect the model by clicking the 'Create Skectch' button on the upper left (box with red circle and square in it).
  

[MarkF]

Not sure how this program works, but all, or most, in the "view" drop down menu gives the DLL error (that's the error I was referring to before).

Are referring to errors appearing in FreeCAD Report View window?

If so, you are going to get a lot of warnings and errors.  I pretty much ignore them unless FreeCAD refuses to do something.  FreeCAD is NOT a polished CAD program.  Even on version 0.19 that I started with, there were things that just didn't work.  FreeCAD is an open-source work in progress.  The newest version has come a long way since then.  Even still, there is a lot of capability available to you even in the old versions.

If you want a polished program, go purchase Fusion 360 or Solidworks.

All that being said, here is a video (using version 0.18 though) which will help you create sketches.

[bostonman]

I'll tinker with it more this weekend. Yesterday was a busy day, and I only had a few minutes to try uninstalling/installing before calling it a night.

In any case, the DLL error appears at the bottom when the program loads. Initially it was a larger window that I closed and it never seemed to reappear as the same size (even after uninstalling/installing).

The same DLL errors are a pop up window that appear whenever I select something from a drop down menu. Unfortunately the 'Start Center' is not what I see at all. My screen is empty with only file, edit, view, and help, drop down menus (and the DLL error on the bottom for a short time at startup).

The 'file' drop down menu only has 'exit' as an option. The 'edit' drop down menu only has 'preferences' as an option, The 'view' drop down menu has 'workbench' with sub options. Most of the sub menu options I've selected show the error: DLL load failed; %1 is not a valid Win32 application.

I believe selecting part and/or part design results in the pop up error window too, but I can't verify at the moment.

This PC has had many things installed over the years with some uninstalls. I have so many programs on it that I've had to combine stuff into groups as the 'start menu' went off the screen. My guess is I have a conflict, so I wouldn't devote too much time helping me since it's an XP system, and who knows what has happened to my PC over the years.

I appreciate the help, but I feel guilty since even I consider running XP silly. At some point over the weekend I'll tinker more, but I'll also try installing on a junk XP laptop I have.

Soon I need to look at what I have for software and make decisions on what I can live without (due to cost) so I can upgrade to a real computer without depending on my work one. Trying to upgrade to newer versions of software isn't..... hmmmm....... as easy let's just say to obtain as in the past. In the past I liked having a piece of software that was universal to stuff used in industry such as Solidworks, or maybe Altium, Xlinx, etc...

Obviously I can use free versions, hobby versions, limited versions, alternate software, alternate open source free software, etc... but knowing I'm designing something in a program that is a skill I can use in my profession is why I like name brand software; but it comes at a cost such as Altium being what.... $15k ?

For the record, about four-years-ago I began piecing together a system on pcpartpicker.com, and found myself overwhelmed with wondering how much I'll spend on software. I blinked, a year went by, blinked again, and now I struggle to view a 3D knob.

[bostonman]

Just an update.

I installed FreeCAD on my XP laptop, and it was night and day. It opened to the start up screen in your post and has many, many menu items now.

Not sure what is wrong with my PC as I've done an uninstall, a registry clean, etc... and FreeCAD gives me the same results.

In any case, I'm not looking for answers as this is XP we are talking about and obviously some software conflict, but wanted to post an update.

[MarkF]

A silly thought..
I doubt it will make a difference but you could uninstall FreeCAD, then install the 64-bit FreeCAD, then uninstall 60-bit FreeCAD, then install 32-bit FreeCAD.  Then try opening FreeCAD again.

My thinking here is that since you installed both versions the 64-bit installer left something behind that the 32-bit installer isn't writing over.  Reaching for straws I know.  But, it might be a quick fix.

On another note.
I have some Bourns PEC11R encoders with 6mm metal D-shafts.
Their actual measures diameter seems overly large.  Hence, our knobs not fitting.
  - diameter = 5.97mm
  - flat distance = 4.47mm

I printed a knob that went on but was tight.  Maybe try a diameter = 6.35mm and a flat distance = 4.90mm

[bostonman]

I doubt it will make a difference but you could uninstall FreeCAD, then install the 64-bit FreeCAD, then uninstall 60-bit FreeCAD, then install 32-bit FreeCAD.  Then try opening FreeCAD again.

You may be a genius, or it was a combination of what I did differently along with your advice. I installed the 64-bit version (still not sure why XP allows me to install it), uninstalled it, installed FreeCAD.0.16.6706.f86a4e4-WIN-x86-installer.exe, but this time I selected 'uninstall' (instead of 'repair') Microsoft Visual C++ Distribution Package when prompted.

Now it's finally showing the start center when I load it - much better and different than what was originally displayed.

I have some Bourns PEC11R encoders with 6mm metal D-shafts.
Their actual measures diameter seems overly large.  Hence, our knobs not fitting.

So you're saying my 3D printer is perfect and your design was off? (that was sarcasm).

For reasons not worth getting into, tonight I removed the Y-axis belt  (forward and backwards) bracket and discovered what once was a very little friction moving bed is now much harder to move.

From my experience, the two thin aluminum plates that mount the bearings and mount the bed are flimsy and bend easy. Most likely these bent over time from pulling off prints and causing stress on the bearings.

I'll print the knobs with my printer in the configuration it's in (i.e. needing calibration and adjustments) because I know what I'm getting at least. The knobs I've printed so far look great, so I'd rather not spend days over the course of weeks with the printer and not finishing the power supply repair.

[MarkF]

If you're talking about the calibration, that should take less than a hour.
You just take the measurements, do a calculation, change and store values via control panel and re-test.

You can just make the measurement and not make any changes to see how far off it is. 
Just measure the distance moved for each axis.

Edit:
  I should also point out that the save and store are two different things.
You can make the changes to try out.  But if you don't store them, the changes will be forgotten when the next time you power up the printer.

[Ian.M]

For reasons not worth getting into, tonight I removed the Y-axis belt  (forward and backwards) bracket and discovered what once was a very little friction moving bed is now much harder to move.

From my experience, the two thin aluminum plates that mount the bearings and mount the bed are flimsy and bend easy. Most likely these bent over time from pulling off prints and causing stress on the bearings.

I'll print the knobs with my printer in the configuration it's in (i.e. needing calibration and adjustments) because I know what I'm getting at least. The knobs I've printed so far look great, so I'd rather not spend days over the course of weeks with the printer and not finishing the power supply repair.

Probably a good choice to deal with the PSU first, as sorting the printer out is likely to be a big job.  However a stiff Y axis *WILL* cause problems with accuracy long before it gets bad enough to cause a layer shift so don't put it off too long.

Getting the bed bearings of a laser cut frame Prusa I3 style printer to run smoothly and normal to the Z axis is a PITA as four bearing beds with rigidly attached bearings are over-constrained.   The bed rails have to be level and exactly parallel to avoid the bed binding or twisting about the Y axis with Y movement.  However the front of the frame is only minimally constrained by the allthread that connects it to the main frame and back plate, and as the front plate generally has to be removed to remove the bed rails, you loose alignment whenever you need to take the whole bed off. 

Your fastening the frame down to a wooden surface may not be doing you any favours here as wood tends to expand and contract seasonally with changing humidity and warp if the surface finish or exposure to air circulation differs between the top and bottom surfaces + the coefficients of expansion of the acrylic frame parts, steel allthread and wooden surface will differ so unless you mounted it with a single fixed point at the center of the back plate, and all other points mounted with lateral compliance (e.g. oversize vertical holes and spring washers over flat washers), the bed rails will not stay levelled with respect to the Z axis and may not even stay parallel and in plane.

Assuming the bearings are still good,  their mounts need to be tightened in-situ with the bed on the levelled rails, otherwise it will invariably bind due to misalignment between the bearings.

There's also dirt and gumming to consider.  Linear ball bearings are highly sensitive to contamination of their raceways, far more so than rotating bearings,  so flushing with a compatible cleaning solvent and relubricating them with light machine oil would be advisable, and if they still don't individually run smooth replace them.  OTOH if you have low friction solid bearings, oil or grease + dust form a grinding paste that embeds in their surfaces and destroys them and the rails.  Cleaning + PTFE drylube may help, but if there is visible wear you'll probably have to replace them and maybe also the rails.

[bostonman]

Probably a good choice to deal with the PSU first, as sorting the printer out is likely to be a big job.  However a stiff Y axis *WILL* cause problems with accuracy long before it gets bad enough to cause a layer shift so don't put it off too long.

This is somewhat my thinking. I just have many projects at the moment, and part of the time I devote to moving unfinished projects out of the way to make room for another project that takes priority.

You're correct, the wood could be causing things to bow/expand/contract. Something I had considered, but weighted the options of a frame that twists when picked up or mounting and hoping for the best. I keep plastic over the top, however, dust could certainly have built up in the bearings too.

The bearings are all metal replacements, but, as you pointed out, the linear bearings are more sensitive. The major upgrades to my printer were (not including upgrading Marlin): replacing the bearings, four 3D printed brackets to hold down the threaded rod (two on each side, one in the front, one in the back), the 3D printed bracket to support the rear acrylic, 3D printed bracket to support the front acrylic, 3D printed frame to make the top acrylic (where the display is) more stable. Also, it's mounted to the straightest piece of wood I could find between HD and Lowe's - but this isn't saying much.

The BL Touch is the only other upgrade I felt was useful (bought it, but haven't installed it), anything more, and felt my money would be better spent on a high quality, less needy, printer.

If plans go correctly, this weekend I should knock off a few major projects which will allow me to free time for the printer. Seeing how stiff the Y-axis slid was quite disappointing to say the least as I devoted extensive time when I replaced the bearings to making sure friction was low.

[bostonman]

Last night the rotary encoder samples arrived. Hopefully I'll have free time to install them, however, doubt I'll have the unit together since I still need to retro fit some binding posts onto the front panel.

Ideally, I probably won't get far enough to reassemble until sometime next week or the following weekend, but I'll post an update.

[bostonman]

I printed a knob that went on but was tight.  Maybe try a diameter = 6.35mm and a flat distance = 4.90mm

The encoders are installed, but this power supply is built with every consideration to save a penny. Disassemble once and you're lucky if the screw holes have enough thread life to catch the ridiculously short tiny screws. Two plastic standoffs broke when I disassembled it, the PCB the encoders mount to are (for some reason) causing one to sit at a slight angle (nothing I need to worry about). I think it's due to the new encoder having a slightly larger base.

A quick test showed the new encoders work. I'm still trying to solve the issue with the three broken banana posts before I fully reassemble.

I'm still familiarizing myself with FreeCAD. Currently I know enough to be dangerous, but one wrong click, and seems I can mess up the entire practice part.

Rather than risk messing up your design, can you resize and post it?

[MarkF]

All you do is double click on the sketch, change the dimensions and export a STL file.
Don't save the file and just reopen it if you mess it up.
That old version will be a bit buggy.

Here's is a 6.4mm hole with a 4.9mm flat

[bostonman]

Thanks.

I'll try printing it in a few days.

A bit buggy or maybe it's just my inexperience using 3D software. At one point I did something to a practice design that suddenly made the solid portion (after I used Pad to make it three dimensional) that showed ghostly triangles on the face. After trying to export it to a STL, it would tell me I need to select what to export (I don't have the exact error message at the moment).

So yes, I'm still using training wheels at the moment.

[MarkF]

When it comes to exporting to a STL, you need to select what to export from the tree (i.e Model tab on the left).

You don't necessarily have to print everything.  You could export the knob without the hole.
In newer versions you can have more than one body.  For instance, a box with one body as the lid and a second body as the bottom.  By selecting one body at a time you can export two STL files (one a lid and one the bottom).


As I remember on the older versions you couldn't mix the 'Part Design' workbench with the others.  You could start with the 'Part Design' and go to another (i.e. 'Draft' workbench to add lettering) but you couldn't come back to the 'Part Design' to add more.  Most of this has changed now in the newer versions.  There are still some limitations that you need to work around even in the latest version.

[bostonman]

For instance, a box with one body as the lid and a second body as the bottom.

Ahhh this makes sense. So basically you don't need to design a box, and a separate design for a lid, it can be all one, but as separate STL files so it prints two separate pieces.

It didn't appear the manual went into detail about exporting to STL, and I haven't had a chance to watch more videos. I tried a CTRL-A to select everything in a tree, and THINK that had worked, but I was under the assumption the design had to be compiled or something rather than using such a method.

[MarkF]

No.  There is no compiling.

In the box example, being able to see that two bodies fit together is a benefit.  Not sure if it's possible in version 0.16.  A work around is two CAD files where you can export the first as a STEP file (good for make parts for use in a PCB design program).  You can then import the STEP file into the second CAD file to compare.



Here each component was a STEP file inserted into the box bottom for layout and sizing.

[bostonman]

Hopefully I do more mechanical 3D stuff. It is fun to see an idea come to life, be able to spin it in the software, and then print it.

Since I don't have experience with software like Solidworks (except the viewer) and whichever other ones are used in companies, I have a general question: are other pieces of software similar in how they function meaning they use constraints and similar methods?

Some of my 2D experience using AutoCAD is that line lengths and such can be manually entered rather than drawing a line and then needing to enter a constraint length.

I'm just curious how closely FreeCAD models high end software.

[MarkF]

I can't help you there.  I don't have any experience with other 3D CAD software.
Like you, I used 2D AutoCAD back in the day.  And even that was doing circuit design.
I have a E.E. degree with 35 years of software development in modelling and simulation.
I retired 8 years ago due to health problems and now spend my time on my HO model railroad.
You can follow along here:  https://www.eevblog.com/forum/chat/model-trains/msg4729595/#msg4729595

All my FreeCAD designs have been mechanical items for my workbench, railroad or household repairs.



Oh.  In FreeCAD you can create a datasheet with your dimensions so you can resize things without going back through all your sketches to change sizes at multiple places.  You enter the variable name from the spreadsheet instead of a numerical value.  I did a lot of compontents for doing PCB designs.  See https://www.eevblog.com/forum/eda/tired-of-searching-for-basic-3d-cad-models/

[bostonman]

Wow, you have some nice diversity.

Most of my 2D drawings are done in AutoCAD 2009, but I find it annoying. I took a CAD course as part of my curriculum, it may have been AutoCAD, but don't remember. In any case, I learned enough to do drawings, and, when I began using it again a few years ago, asked some co-workers at a previous job who used AutoCAD about a few areas I was (and remain) confused in. I know enough about AutoCAD to create basic drawings, however, I probably take the long way to create stuff which makes tweaking drawings a pain.

The last few years I've had a habit of creating 2D drawings in AutoCAD for many projects just for reference. This past summer I had an irrigation installed and used the 2D aerial view of my property I created a few years prior to map all the sprinkler head locations.

I went around my property measuring distances of the sprinkler heads, entered them into my drawing, color coordinated them by zone, did an approximate underground pipe routing drawing, etc...

[MarkF]

Ya, getting accurate measurements is sometimes the hardest part of the job.

The CAD training I had in school involved paper and pencil.   
I still have all my drafting triangles, mechanical pencils, T-square, etc.  Collecting dust.

The version of AutoCAD I used run on DOS (prior to Windows).   

I bought a copy of TurboCAD years ago, but never got the hang of it.

[bostonman]

Earlier I printed the knobs at 0.12 layer height and began reassembling the power supply. The knobs look fantastic and add a bit of style since they give it (green) color.

The most recent STL you provided had them fit a bit loose. It was actually perfect because I didn't risk applying pressure to the new encoders trying to force them on (even the originals require a good amoutn of force to slide on).

Due to the cheap (and extremely tiny) plastic standoffs breaking off that hold down the PCB, I used some epoxy to hold down a few areas of the PCB, so I put a dab on the encoder shafts since I had some fresh mixed stuff.

In the future, if this power supply needs to be disassembled, the front panel will not go back together again. The screws are tiny and the standoffs break/strip, so the need to remove the knobs will probably never happen; unless I'm willing to clue all the PCBs back onto the plastic case.

Due to the many revisions of the CAD file you provided, I'm a bit confused on which one is the "final" version. I'd like to keep it so I can tweak it for other D shaft knobs I may need (actually just bought a used Lacroy scope today which is missing a knob, so I may need to print one for that too).

Which revision CAD file should I download and keep that can be easily edited?

Most likely I'll move onto tightening the belts and calibrating my 3D printer since I don't have an immediate need for it. Yesterday I printed a 30x30x10 square I made in FreeCAD to check the calibration. Ironically it was almost perfect in two of the three sizes (I forgot which one was the X and Y, so I don't know which one is off, however, I'll be calibrating all axis).

[MarkF]

Here are the Knob2 files for both the old 0.16 and the current 0.21.2 versions of FreeCAD.
These files have the dimensions for the D-shaft of 6.4mm diameter hole and 4.9mm flat
used in the last STL file I posted.

[bostonman]

Great, thanks again!

Hopefully your design will help others too. If all it needs is a few tweaks to resize the overall knob, then this could be quite useful to others since test equipment is prone to broken knobs.

This has certainly opened my eyes to being reminded of becoming more knowledgeable with 3D designs. What a great time we live in that helpful people can create something in one part of the country/world, send the file, and the end user can just print the part to fix their issue.

[bostonman]

MarkF,

I have a few questions but not sure if I'm going to ask them correctly. Since you created the 6mm shaft knob, referencing it may be the best way to ask my questions.

Basically I'm trying to expand my 3D modeling knowledge and using FreeCAD to do so. Much like other 3D models I've seen, you have several separate sections such as: Revolution, Sketch, Pad001, Sketch001, Sketch002, etc...

As I click on different sections of the knob, specific sections get highlighted. I'm curious why or when is it appropriate to create a separate sub part/section.

To be more specific, before I thought if I were to create a 3D model of a car, I'd create the body, engine, tires, etc... as individual pieces. What you seemed to do is create many separate pieces within just one part.

Recently I downloaded the STEP file for a BNC connector for reasons not worth getting into. The STEP file had numerous individual pieces all within just the BNC. So again, I'm wondering how/when this is done.

With your knob, as I click on each section, it gives me the impression numerous separate pieces were used, but I can't follow it.

Also, although I have several lingering questions I'm trying to work through with FreeCAD, one basic general question is say I wanted to add something like a plate for the knob to sit on. Let's say I wanted to make it a trophy. How do I make the plate "touching" the knob so it's all one piece that gets printed? I think this is called a face, but I haven't found any tutorials that explain this.

[MarkF]

I guess my first question is which version of FreeCAD are you referring to?

In the old version (discussed earlier), it is not possible to create multiple parts.

As far as order is concerned, in many times you don't have a lot of choice.
Certain operations depend of previous ones.  For example, you can't cut a hole in a part
you haven't created.  If you wanted to add a plate to the knob as you suggest, you would
just create a new sketch to the last operation in order to create a pad or perform a
revolution operation.  In the newer versions of FreeCAD, you can create multiple bodies
to build up your model.

The order you create the model depends a lot on what you're modelling.  Most likely, you
will build the model from the inside out.  Mainly you create a sketch, use that sketch
to perform a further operation (pad, revolve, cut), and then a boolean operation in some cases.
After you're comfortable, you can move to the 'draft' workbench to add text.  More advanced
operations to learn are the loft and pipes to create a curved surface or to draw a sketch along
a path.  In the beginning, you try to do things a certain way and find out you can't get from
point A to point B and will need to do it differently.  Especially in the older versions.
I do most of my modelling in the 'part design' workbench building sketch upon sketch.
Think of a sketch as the shape of the tool you will use to draw with.

I can suggest a few YouTube channels:
  - https://www.youtube.com/playlist?list=PL7eiW2bt21YU6QEbly78kUgQCNEiDUwSH
  - https://www.youtube.com/playlist?list=PLWuyJLVUNtc0UszswD0oD5q4VeWTrK7JC

Perhaps a photo of the two versions of FreeCAD:
 

[bostonman]

I watched some of those videos and will watch more as time goes on.

Recently I wanted to make a shape (using Free CAD v0.16) and attached a general sketch. In order to make this, I made the outside circle 50mm, the next one in 40mm, and then used pad to give it height.

After I added another shape making the circle 40mm (so it meets the previous circle), the inside one 15mm, and used pad to bring the height slightly less than the other shape.

Although the object came out correctly, I sense this isn't the correct way to do it; nor does the slicing software seem happy because it's doing some funky stuff with the layers. If I try adding a chamfer to the outside (higher raised) circle, the slicing software seems to not see it (even though I exported all the associated stuff in the left side panel).

I'm not asking for someone to create this, but only asking whether this needs to be done as two sketches, add something, or whatever, so I can learn. Keep in mind, I'm still trying to wrap my head around creating parts beyond a simple 2D sketch.

Also, I've yet to find why FreeCAD has a robot workbench. Does anyone know the reason for this? Although it's cool, I don't know what purpose it serves.

[MarkF]

I think the problem is that the inner disk and the outer ring are being seen as two different parts.
(i.e. the 40mm intersection is exact between the two.)
FreeCAD has some problems with exact edges like that.
You can try changing the inner disk to have its diameter equal to the diameter of the ring (i.e. 50mm or 40.001mm).

A better way of creating the part may be to create a disk with 50mm diameter with 20mm height and 15mm hole.
Then cut out the 40mm x 10mm hole from the inside.

[bostonman]

I think the problem is that the inner disk and the outer ring are being seen as two different parts.

From how I interpreted the image/stl, this was my thought too.

A better way of creating the part may be to create a disk with 50mm diameter with 20mm height and 15mm hole.
Then cut out the 40mm x 10mm hole from the inside.

I'll try this method tonight.

[MarkF]

I just recreated the part as you described including the chamfer without any issues in version 21.2
This might just be something that works better in the newer version of FreeCAD.

Like I said a while back:  "Sometimes you just have to tinker with how you create a part to make it work."


Also, I was able to create a STL and slice your zip file part without issue.
This also might be how the new version of FreeCAD creates STL files.


FYI: I'm using the latest PrusaSlicer on Windows 7.
I left Cura in the dust since they don't want to support Windows 7 any longer. 
Also, I hated the way you have to control Cura's view angle on a laptop without a mouse.
I wish both slicers would adopt FreeCAD's SHIFT/ALT pan and rotate control.

[bostonman]

I have a Win7 laptop as well that I can install V21.2 on.

Like I said a while back:  "Sometimes you just have to tinker with how you create a part to make it work."

I fully agree and it's why I tried making the second circle equal to the diameter of the other circle. In my mind, it didn't make sense because, as you stated, and I assumed, it's making two separate parts that "touch" each other rather than uniform.

My point is that I did spend time tinkering. In my slicing software, one view didn't show the chamfer, but the 3D view did, however, it also showed support material embedded in the inner circle; this is when it being wrong was obvious.

I attempted to print the part for fun, but it came out looking worse than expected.

[bostonman]

I'm uncertain whether I should start a new thread.

Periodically I tinker with FreeCAD (0.16) and trying to learn all the options. One option is the 'groove' option and I watched a video ().

Following the video to a degree, I managed to create a groove, but I don't understand what I actually did.

At approx. 2:40min into the video he creates a rectangle on top of the cylinder. First he created a cylinder, created a rectangle on top (for some reason), created the groove pattern, and then used that to make a 360 degree groove around the cylinder.

How is this different than using rotation?

Why was the rectangle needed?

Due to errors in my attempts, does the groove pattern need to be spaced a specific distance from the vertical axis?

It got somewhat confusing why another sketch was created, then pad was selected, another sketch, etc...  I managed to create a funky looking groove in my cylinder, but don't quite get the reasons for the steps including the last three or four steps after the groove was completed (and the rectangle was removed).

[MarkF]

How is this different than using rotation?
- The 'groove' tool basically does a rotation and then a cut.  It's doing multiple operations with one tool.

Why was the rectangle needed?
- The little rectangle on the top was to provide a reference face along the X-Z axis for the groove tool to operate upon.

Does the groove pattern need to be spaced a specific distance from the vertical axis?
- In this example, the 'groove' pattern will be revolved around the Z-axis.  So, you can't have any part of the pattern on the negative X-axis.  If you place part of the pattern on the Z-axis, the 'groove' tool will cut the object in half.

It got somewhat confusing why another sketch was created, then pad was selected, another sketch, etc...
- As mentioned above, the 2nd sketch and pad was to provide a reference plane for the 'groove' tool.  In the newer versions of FreeCAD, I didn't need to create that 2nd sketch.  I was able to reference the X-Z plane directly.  You have a more ways of creating reference planes in the newer versions.

[bostonman]

Sorry, I used the term 'rotation' and meant 'revolution' (located in the design drop down menu). At one point I tinkered with revolution, and, when I accomplished a groove pattern, wondered if a difference exists.

I was able to reference the X-Z plane directly.  You have a more ways of creating reference planes in the newer versions.

I assumed the groove "reference" was the vertical part of the groove pattern, however, if this is an outdated method and revised in later versions, no sense pondering on the topic.

[MarkF]

I don't know if there is a question there...

FreeCAD 0.16 was released in April 2016.
While it is terribly out of date, you still need to understand how
that version of the program works in order to be productive.
It wouldn't be important to others, but it's worth your time.

Let me pose a modification to the exercise in the video.
How would you rotate the groove pattern around the X-axis instead of the Z-axis?
I haven't tried this.

[bostonman]

How would you rotate the groove pattern around the X-axis instead of the Z-axis?
I haven't tried this.

That's a good question and I'm uncertain.

While I grasp some of the concepts, I don't necessarily understand the steps. At the end of the video he adds a sketch to the face of the rectangle, does something else, and makes it "vanish". Not sure why the rectangle sketch just can't be deleted at that point, however, my point is that it's a step I can easily follow but don't understand.

Per your question, a twist is: after making a cylinder, if I want to attach a square perpendicular to the cylinder, how do I attach the face? Each time I tried this last night, the square (or rectangle) would attach itself to the center of the x-axis.

[MarkF]

Not sure that I've figured out how version 0.16 is working.

However if you draw a cylinder around the z-axis as in the video.

Select the top cylinder end face as the reference to create the reference sketch (as the video).
Draw a square with two edges on each of the x-axis and y-axis in the positive direction.
Pad the reference square to a cube.
(Basically, make the little rectangle and pad in the video into a cube for more clarity.)

Now you have a cube which you can use to reference any of the faces in order
to create your cutting pattern.  The revolve then allows you to rotate the cutting pattern
in either the horizontal or vertical directions.

Clear as mud???   For me too.

To answer an earlier question, you can't delete this reference cube because that would
break the draw path used to update the part.  You can only add a cut of the cube at the
trailing end of the operations.

[bostonman]

I’ll tinker with it over the weekend.

Just for the record, I’m not necessarily trying to perfect learning FreeCAD, but more about trying to understand the foundation of it so I can understand what I’m actually looking at when I create a model. The goal and obvious method is to use the latest version rather than learn outdated tools, but I like learning the foundation rather than just steps.