Author Topic: Direct Drive?  (Read 3734 times)

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Offline Microdoser

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Direct Drive?
« on: June 01, 2021, 01:23:55 pm »
Ive been having issues with my Bowden tube getting loose, so I wondered how many of you have fitted a direct drive extruder to your printer, and if you did, which one did you choose?

Also, how have you found it to be?
 

Offline beanflying

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Re: Direct Drive?
« Reply #1 on: June 03, 2021, 09:33:50 am »
Better fittings and Capricorm tubing https://www.captubes.com/ will solve a lot of your issues. Creality sells it now but I am not sure if they have stopped using bottom of the barrel fittings. My Ender and CR-10S work great post the upgrade without any fuss.

Direct drive lots of options out there now but keeping the weight down if you want to go faster is important and look at the usual youtube suspects for what is the latest and greatest. I am behind the times with these.
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Offline Whales

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Re: Direct Drive?
« Reply #2 on: June 03, 2021, 11:12:29 am »
I am under the impression that direct drive is more common than bowden?

I've been using the cheapest 3d printer I could find -- a $200AUD kit off eBay ("Geeetech i3") -- with the simple direct drive it came with and it has been working fine. It's literally a stepper, a toothed gear on the stepper (to grip the filament), some bits of metal, a couple of rollers, a spring and a screw to adjust pressure.  It did take some initial fiddling & modding: I increased the stepper driver current and took the heatsink off the side so I could see where the filament was feeding (the parts the heatsink was attached to barely get above ambient).

N.B. said cheap printer required two days of assembly and lots of tweaks overall to get working well!  Not for the faint hearted.

Offline MarkF

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Re: Direct Drive?
« Reply #3 on: June 03, 2021, 11:34:24 am »
- Creality CR-10 Mini
  -- Capricorn Bowden PTFE Tubing
     --- Bowden Clips  or try these: https://www.thingiverse.com/thing:3722071

Never looked back.  No more problems.

When installing the bowden tube, I leave the fitting about 1/4 turn loose, push tube completely in, tighten fitting.
This final 1/4 turn forces a little more pressure on the tube to insure that it is tightly seated.
 
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Offline Microdoser

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Re: Direct Drive?
« Reply #4 on: June 03, 2021, 11:13:59 pm »
Better fittings and Capricorm tubing https://www.captubes.com/ will solve a lot of your issues. Creality sells it now but I am not sure if they have stopped using bottom of the barrel fittings. My Ender and CR-10S work great post the upgrade without any fuss.

Direct drive lots of options out there now but keeping the weight down if you want to go faster is important and look at the usual youtube suspects for what is the latest and greatest. I am behind the times with these.

I'm already using Capricorn tubing and the fittings that came with it. My main concern is quality not speed, from what I have read that improves with direct drive.

From further examination of when it happens, it seems to be a problem of filament solidifying in the nozzle. Running higher temps seems to stop the problem, although I am now at 220-225C for PLA... I am also printing some extra thick clips to make sure the push-fit plastic bit does not work to a place where it removes pressure on the pipe.

This is one reason why I am thinking of changing the whole hotend, and if I am doing that then all options are on the table, including a direct drive conversion at the same time.

- Creality CR-10 Mini
  -- Capricorn Bowden PTFE Tubing
     --- Bowden Clips  or try these: https://www.thingiverse.com/thing:3722071

Never looked back.  No more problems.

When installing the bowden tube, I leave the fitting about 1/4 turn loose, push tube completely in, tighten fitting.
This final 1/4 turn forces a little more pressure on the tube to insure that it is tightly seated.

I'll give that a go, I have seen that some people push extra tubing through the nozzle before screwing on the fitting then splay out the tubing and lightly hammer it flat to the end of the fitting so it forms a flat end that is screwed tight to the internals. Wouldn't help with the hotend though. Your tip might.
« Last Edit: June 03, 2021, 11:18:18 pm by Microdoser »
 

Offline Joel_l

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Re: Direct Drive?
« Reply #5 on: June 04, 2021, 12:57:39 am »
On my TronXY Pro, I changed the bowden tube setup to a mosquito magnum and bondtech drive, has worked flawlessly. Occasionally I print with Filaflex ( super flexible), it was hit or miss with the bowden tube even at slow speeds. With the new setup, very reliable prints.
 

Offline xrunner

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Re: Direct Drive?
« Reply #6 on: June 04, 2021, 11:24:02 am »
Ive been having issues with my Bowden tube getting loose, so I wondered how many of you have fitted a direct drive extruder to your printer, and if you did, which one did you choose?

Also, how have you found it to be?

Funny you should ask this now because I should be getting a kit from 3D fused to convert my system to direct drive. I have their linear rail system on all my axes so this should be fun. But I'm trying my own experiments along with it. This is it -

https://3dfused.com/product/linear-rail-direct-drive-mount-kit/

It's just a water jet cut aluminum plate with some associated parts and an extension cable. But the idea is to flip the original extrusion stepper and re-mount it. I tried some experiments already before even getting it (with the original bowden tube setup). I added more weight to the hot end with steel blocks and clamps to see if that would affect anything I printed out. After printing several test prints I didn't see any bad effect from that weight having to be pushed.

But I'd like to reduce the weight anyway. The X,Y, and Z motors are smaller than the extrusion stepper. They are 42-34 motors and the E motor is 42-40. Creality wanted to have a motor with more torque on the E stepper to help push through the bowden tube. But I wondered if I could get away with the smaller motor after the conversion. After the conversion the motor will not have any length of curved bowden tube to push through - it's a straight shot, effectively no resistance at all (from tubing). I purchased another new 42-34 stepper and substituted it on my system in place of the E stepper (42-40) as it is, just to see what would happen. Pure experimentation. First, I weighed the two motors. The larger motor weighed 289.7 g and the smaller 214.6 g. A difference of 75.1 g.

Well, at the printing speeds I've always used - nothing at all bad happened - no skipping. I tried quite a few different prints and they all came out fine with the smaller E stepper. So I'm very confident that when installed on the direct drive the smaller stepper will work fine, and present less weight for the X axis to push. Should be getting the parts Monday.
My friends say they're procrastinators. I say I've been meaning to tell them for years, but I just keep putting it off.
 
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Offline Microdoser

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Re: Direct Drive?
« Reply #7 on: June 04, 2021, 11:41:36 am »
After yet another failed print, I've ordered a Hemera. I've fixed the problem with the tube becoming loose, but now the filament is grinding and breaking at the extruder just before the tube and this is at 220C using PLA. I don't have loads of time to troubleshoot what should be a perfectly functional part, and I'd rather swap it all out for new problems, hehe. Also at some point I may want to print flexible filament and I hear the Hemera copes with those quite well. (on top of that, their factory is on my route from home to work so if their product is pants, they will become sick of my face at their door)

It seems that there is no absolute king of direct drivers, and it looks easier to install than some of the others and comes with a hotend built in which makes it cheaper than buying a separate hotend, although this may limit upgrading in the future.

It arrives on Monday, once I've fitted and tested it I'll post how I find it in case someone reads this thread in the future.
« Last Edit: June 04, 2021, 11:45:23 am by Microdoser »
 

Offline Microdoser

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Re: Direct Drive?
« Reply #8 on: June 10, 2021, 09:23:21 pm »
Well, wouldn't you know it, as soon as I ordered the Hemera the printer worked flawlessly. The Hemera turned up, and I've fitted it all except the BL-touch, which requires a couple of bolts I don't have laying about (m3x18mm). They turn up tomorrow, then I can fit the BL-touch bracket and tidy up the wiring.

It seems to be working though, gears turn and the block heats up and seems to be reading the right temperatures.

I've kept the bowden tube in place and removed the stepper that used to push the filament. The tube will just be a filament guide, but it means I can use the filament runout sensor. I discovered half way through fitting it (old parts removed, looking at fitting new parts) that the bracket I had printed was missing two holes and also stopped the head from touching the x-axis end switch so it was out with the drill and cutters and now it fits and does not interfere with the switch. When I get it running I'll print another bracket if this one bothers me, it is fitted pretty solidly though.
 

Online Monkeh

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Re: Direct Drive?
« Reply #9 on: June 10, 2021, 09:30:02 pm »
the block heats up and seems to be reading the right temperatures.

It will always reach the target temperature. That doesn't mean it's the actual temperature.

Did you adjust the type of thermistor to suit?
 
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Offline Microdoser

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Re: Direct Drive?
« Reply #10 on: June 10, 2021, 11:31:32 pm »
the block heats up and seems to be reading the right temperatures.

It will always reach the target temperature. That doesn't mean it's the actual temperature.

Did you adjust the type of thermistor to suit?

Not yet. It is on my plan of action though. All I have done is a hot tighten of the nozzle then I shut it down. I was happy to have it heat and show a reading change, turn the gears in the right direction, and move x,y, and z, so I know all the connections are connected. I'm waiting for the M3x18mm bolts to arrive tomorrow so I can fit the BL-Touch, and once it is fully assembled I'll flash the firmware (and touchscreen) with Marlin and go through the options, including changing the thermistor setting to type 5, adjusting the microstepping, activating thermal runaway sensing and so forth.
 

Offline xrunner

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Re: Direct Drive?
« Reply #11 on: June 11, 2021, 11:14:31 am »
Well I have to be honest. The direct drive was a flop.  :(

There was  nothing wrong with the parts from 3D fused - the new mounting plate, cable , and other small parts. It's simply the fact that the prints never looked better, and usually looked a bit worse, than the bowden tube setup. I printed out a set of models to compare to before I switched it all out.

I played with the setup for many hours over two days, did all the calibrations (e steps, flow, bed leveling, retraction, ...). I used the original e stepper motor. I used a new nozzle. I never got it to look as good most of the time. I also found that I needed to print a skirt for every print with the direct drive, to get the main print first layer started off right. I hardly ever had to do that with the bowden tube.

I dunno. What is the hypothesis? I imagine that the bowden tube does a little "mechanical averaging" of the stepper output. I think it smooths the sharp and exact steps of the stepper, so helping to smooth the output at the nozzle. But I have no other explanation. I do know what my eyes tell me though. I worked yesterday morning switching it all back to the bowden tube, and now it works like it used to - better than the direct drive.

For now I'll leave it as-is. If I can find any rational explanation for what I experienced and a way to make it better, I'll try it again sometime.
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Offline Whales

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Re: Direct Drive?
« Reply #12 on: June 12, 2021, 12:00:54 am »
More weight on print head -> more shakes -> lower quality print.

Bowden:
 + Better quality prints due to lower head-weight
 + Faster printing possible (without sacrificing quality)
 - Can't use flexible filaments as easily
 - Sometimes more difficult to calibrate retraction
 - More PTFE

Online Monkeh

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Re: Direct Drive?
« Reply #13 on: June 12, 2021, 12:24:31 am »
More weight on print head -> more shakes -> lower quality print.

Bowden:
 + Better quality prints due to lower head-weight
 + Faster printing possible (without sacrificing quality)
 - Can't use flexible filaments as easily
 - Sometimes more difficult to calibrate retraction
 - More PTFE

A properly rigid motion system is quite capable of going far faster than a bowden extruder is capable of performing the excessive retractions needed.

But yes, the extra mass means you will need to slow down a bit on floppy machines.
« Last Edit: June 12, 2021, 12:32:10 am by Monkeh »
 

Offline Microdoser

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Re: Direct Drive?
« Reply #14 on: June 14, 2021, 11:02:34 pm »
Well it's taken a week of fiddling about, mainly software (firmware) issues and understanding how to set things up properly.

Printing seems to be faster, mainly because 0.5mm of retraction can happen much much faster than 7mm of retraction. No stringing, bridges are good, bed adhesion is a bit harder but lowering the nozzle, going slower, and bumping up the bed temperature and nozzle temperature has sorted that. Pyramids have sharp points. Overhangs suffer sooner, but that is because I have not yet printed a blower duct for part cooling.

Considering that I am still using my old profile, the prints are great so far. I'll see if I can get them as good as with my bowden setup.

I know already that I will be printing new brackets, ducts, and fixtures to fit it all the way I want but at least it is working well enough to do that.
 
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Offline xrunner

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Re: Direct Drive?
« Reply #15 on: June 14, 2021, 11:53:40 pm »
Glad it looks like it's going to work for you microdoser. Now I'm working on a BLTouch upgrade. I've wanted to try that for a year now. I just got it yesterday and am working on the firmware changes. Hopefully it'll be worth the trouble.
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Offline Microdoser

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Re: Direct Drive?
« Reply #16 on: June 15, 2021, 12:01:03 am »
Glad it looks like it's going to work for you microdoser. Now I'm working on a BLTouch upgrade. I've wanted to try that for a year now. I just got it yesterday and am working on the firmware changes. Hopefully it'll be worth the trouble.

I would say it is. It took a little tweaking to set the probe offsets and bed settings to get the probing where I wanted but because it measures the distortion over the surface of the bed IMO you can get a much better first layer with one than without. I set the bounds of the testing grid using Octoprint and the G29 code. Not sure how familiar you are with Marlin (I assume you are using Marlin) but this page has a list of all the commands n stuff. Very handy.

https://marlinfw.org/docs/gcode/G029-abl-bilinear.html
 
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Offline xrunner

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Re: Direct Drive?
« Reply #17 on: June 17, 2021, 12:29:14 pm »
I would say it is. It took a little tweaking to set the probe offsets and bed settings to get the probing where I wanted but because it measures the distortion over the surface of the bed IMO you can get a much better first layer with one than without. I set the bounds of the testing grid using Octoprint and the G29 code. Not sure how familiar you are with Marlin (I assume you are using Marlin) but this page has a list of all the commands n stuff. Very handy.

https://marlinfw.org/docs/gcode/G029-abl-bilinear.html

Just to follow up - I got the BLTouch working and set up. Wow - I'm wondering how I got along without it now!  :) Amazing first layer and quite an improvement to the system.  :-+
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Offline beanflying

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Re: Direct Drive?
« Reply #18 on: June 19, 2021, 04:18:35 am »
Another one to follow and see if they debug it some more. Certainly getting the weight down compared to other solutions.

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Offline Microdoser

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Re: Direct Drive?
« Reply #19 on: June 19, 2021, 11:43:31 am »
Another one to follow and see if they debug it some more. Certainly getting the weight down compared to other solutions.



I did consider that one, but decided I wanted a known quantity/quality. Looked interesting, but most sources I saw mentioned quality control issues, so I went with established tech.

If they get those sorted out, then it looks very promising.

On my side of things with the Hemera, I can now print faster than I could with the stock hotend/bowden combo, now I have printed a cooling fan duct overhangs are now failing at the same point, and there is no chance of the bowden tube popping out because of excessive retractions. Stringing has totally gone, but occasionally there is some blobbing. I will be looking into nozzles and settings with the aim of getting rid of that. It may be the result of a first layer that is not thick enough.

If I can get the quality the same, and print at least as fast, then I will regard it as a success that fixes the problem it was meant to. On the plus side, I will be able to print flexible filaments now.
 

Offline xrunner

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Re: Direct Drive?
« Reply #20 on: June 19, 2021, 11:50:28 am »
I watched it. Yea he got it to make prints. But were they better than before ?

 The problem I have with a lot of these direct drive reviews and how-tos is that they don't do a before and after comparison with any prints made with a previous extruder set-up. Like say, does this direct drive produce better parts than a standard Ender 3 with bowden tube, for example? If so, show the details side-by-side.

Of course they work, as I got my attempt to. Mine worked OK. It wasn't that you couldn't use it for the same prints I was doing before. The fact was upon comparison to a set of prints I made before I converted it, the fine details simply were not of the same overall quality. I didn't want to admit it, but the situation forced me to say (for at least this attempt) it was a flop.

If I go down that road again, I'm going to do the same thing - print out a set of printer test/calibration models and set them aside. After the conversion I will compare to the set I printed out. If the DD doesn't produce better quality prints, then why did I just waste my time?

Like this BLTouch upgrade. It's not even a contest. The first layer print quality and adhesion is flat-out better than it ever was since I've had this printer. I can see that it's better than manual leveling by inspection. I just want to see the quality comparison of printed models side-by-side for direct drive.
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Offline Microdoser

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Re: Direct Drive?
« Reply #21 on: June 19, 2021, 06:03:29 pm »
If I go down that road again, I'm going to do the same thing - print out a set of printer test/calibration models and set them aside. After the conversion I will compare to the set I printed out. If the DD doesn't produce better quality prints, then why did I just waste my time?

I have done this, with prints of a Benchy of course. Neither are perfect. On the hull there are layer lines on both, and there are slight imperfection on one that are not on the other (the Hemera seems to have a 'stickier' nozzle and some filament is blobbing sometimes but I think that is a nozzle issue, not a direct drive issue) but overall I think the Hemera is producing better prints than the stock hotend with Bowden setup. In combination with slightly faster prints and eliminating the problem I had where the bowden tube would wear and then pop out of the fitting, I am quite satisfied.

Here are some images of the Benchies printed in white PLA, the stock bowden is on the left, the Hemera direct drive is on the right. Apologies for the quality of the images.

Some differences I have noticed, the bowden has a lumpy smoke stack on the roof, the Hemera has a brown blob next to the rear porthole, the base of the bowden does not look as good to me as the Hemera, the top surfaces look better with the Hemera, seams are less pronounced and the bow looks better with the Hemera, there is some banding on vertical surfaces with the Hemera.

I am of the opinion that some tweaking with my settings could eliminate most if not all the imperfections from either setup.

EDIT: It seems that the horizontal lines and blobbing are both caused by the same issue, that being something related to extrusion temperature or flow rate. I will play about with setting a bit more and see if I can improve this.
« Last Edit: June 20, 2021, 10:58:32 am by Microdoser »
 
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Offline Microdoser

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Re: Direct Drive?
« Reply #22 on: June 19, 2021, 06:04:42 pm »
Some more images that were over the 5Mb limit
 
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Offline xrunner

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Re: Direct Drive?
« Reply #23 on: June 29, 2021, 12:57:36 am »
Well after a lot of research I'm going to try this gizmo -

https://zesty.tech/

The Zesty Nimble remote direct drive. They have a new version coming out so I can't buy it yet but I think it sounds like a pretty neat idea. We shall see ...
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Offline Microdoser

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Re: Direct Drive?
« Reply #24 on: June 29, 2021, 10:37:14 am »
Well after a lot of research I'm going to try this gizmo -

https://zesty.tech/

The Zesty Nimble remote direct drive. They have a new version coming out so I can't buy it yet but I think it sounds like a pretty neat idea. We shall see ...

Ah, yes. I had heard of these. Motor set to one side, remotely driving a geared direct drive extruder with a drive cable. Sounds like the best of both worlds.

I'll be very interested to see some before/after test prints, especially if the print time is recorded.

One thing I will be watching is how well they age. My first thought is that the drive cable might start flexing with age, or wearing at the connection points. I'm not familiar with using drive cables, so I don't know if these are problems they suffer from.
 


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