Author Topic: EEVblog #843 - David's rPrint 3D Printer  (Read 23687 times)

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Offline EEVblog

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EEVblog #843 - David's rPrint 3D Printer
« on: January 22, 2016, 04:34:43 am »
David tells us all about his rPrint 3D printer. A university project he has been working on for the last 9 months.
Everything is custom, including the world's lightest weight direct drive extruder head, Sarrus linkage build plate, linear rail guides, and his awesome bubble enclosure.
Not to mention his own custom controller, gcode interpreter, and highly optimised C++ string libraries.

 

Offline GAD

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #1 on: January 22, 2016, 05:39:08 am »
 Cool stuff. Should of had that kickstarter ready! :)
 

Offline poida_pie

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #2 on: January 22, 2016, 06:28:02 am »
Well done David. Building a system such as this will develop lots of important skills (integration of systems for one)
Best of luck with the assesment.
 

Offline V42bis

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #3 on: January 22, 2016, 06:43:03 am »
Excellent job. if you get a chance please post some pictures without the PMMA bubble removed. 


Sent from my iPad using Tapatalk
 

Offline Barny

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #4 on: January 22, 2016, 07:15:41 am »
David, you have done a really good work.

Its funny to see the way a electronic guy is solving problems aut of the view of an mechanic guy.
(I'm an machine fitter / draftsman / CNC-machine programmer)

For example:
You said that aluminium parts are cheaper then steel parts.
Thats only the case if you mill the steel parts.
If the parts are laser cut, steel parts are much cheaper.
Because steel sheets are less expensive than aluminium sheets.
I know here a company, which lasercut the parts and make all the threads on the same machine.

If you have problems with harmonics, bend the part on the sides or screw ribs on it to lift the resonances over the hearable area.


About the zinc plated steel plates:
Your's are "blue" galvanic zinc plated steel plates.
There are yellow and black versions of galvanic zinc plated steel.

The funny pattered coating mentioned in the video is a hot dip zinc coat.
Its much thicker than galvanic coat.
Its used at low precision parts like fences, suport beams,...
I you buy zinc coated sheet metal, its hot dip zinc coated too.


Its funny to see that the electronic guy moan about countersunk screws. (I'm moaning about getting matching resistors, capacitors,... ;) )
Nearby my home, there are many shops for industrie suply which sells all sorts screws.
And that to a better price and quality than at ebay.
Dont go to a DIY superstore. They sell the screws with bad quality at ridiculous high prices.

By the way:
I dont use the countersunk screws with philips head.
They are a pain in the ass if you have to remove them after a couple of years.
I always use screws with hex-head or torx-head.
« Last Edit: January 22, 2016, 07:23:00 am by Barny »
 

Offline alexanderbrevig

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #5 on: January 22, 2016, 08:12:39 am »
Absolutely amazing work David! I'd hire you in a heartbeat.  :-+

Offline adam1213

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #6 on: January 22, 2016, 09:10:30 am »
Neat design.
David - you mentioned your aim was to design for speed. Out of interest have you benchmarked your printer against others / how do you think it would compare in terms of various workloads.
 

Offline AndreasF

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #7 on: January 22, 2016, 09:50:40 am »
Very nice!  :-+

One thing isn't clear to me (but I may have missed it): how does the filament get into the enclosure, where does it sit?
my random ramblings mind-dump.net
 

Offline SL4P

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #8 on: January 22, 2016, 10:15:50 am »
Absolutely love the work you put into this.
I have to ask though...  It doesn't look like you implemented any interlock opening the 'door' - which suggests a kid (or engineer) could open the lift & release panel while the unit is running.  I'm sure you have thought about this - but interested in your comment.
Don't ask a question if you aren't willing to listen to the answer.
 

Offline HAL-42b

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #9 on: January 22, 2016, 10:19:39 am »
Ah the young whipper snappers moving too fast for the old camera man :-DD
 

Offline hamdi.tn

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #10 on: January 22, 2016, 10:50:13 am »
AWESOME  :clap: cool project and nicely done , totally admire this kind of enthousiasme for projects.
And yes it's the exception regarding university projects, where most of them are crap or too much theoretical, or the guy end up doing nothing . good job really good job  :clap:
 

Online German_EE

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #11 on: January 22, 2016, 11:20:02 am »
Great work there David, technically the stuff that students have to do these days is miles ahead of what I had to tackle when I did my degree so well done.

However, I'd like to suggest a new drinking game. Play the video back and every time you say "like" you have to down a glass, by the time the video ends you'll be sozzled. Don't worry, it's either nerves or presentational style and I'm sure that it will be better in your next video. Ask that Jones guy, he seems to know what he's doing  :)
Should you find yourself in a chronically leaking boat, energy devoted to changing vessels is likely to be more productive than energy devoted to patching leaks.

Warren Buffett
 

Offline brutester

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #12 on: January 22, 2016, 12:14:06 pm »
Speaking for "wireless limit switch" @47:10 , I can give a hint - TCRT5000 , which is an "Reflective Optical Sensor with Transistor Output". It has photodiode at 940nm and photransistor, which give 0.2 to 15 mm object detection. Good enough to position your head at top left (or where ever you want). From there on, "everything is relative" on your coordinate system. It may not be very precise, but you don't need that.
 

Offline StuUK

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #13 on: January 22, 2016, 12:19:24 pm »
Excellent work!!! enormous  undertaking for one guy in those timescales.
 

Offline SixD

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #14 on: January 22, 2016, 01:04:55 pm »
WOW, just awesome that one guy managed to design an entire 3d printer.
BTW: If you still do not have a website, I am willing to make one for you (for free ofc) since I am actually a web developer.
 

Offline hlavac

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #15 on: January 22, 2016, 01:13:49 pm »
Great work David ;) We want more photos!

But don't celebrate yet, theres plenty work to do still, until it actually prints.  >:D You are no doubt in for a few surprises there.
Good enough is the enemy of the best.
 

Offline Brumby

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #16 on: January 22, 2016, 01:26:39 pm »
I like what I see - and the approach as well.

I would be very interested to see this in production, but before I reach for the wallet, I'd like to see some specifications, performance comparisons and see some prints.  Early days yet, I know ... but I would be really interested!
 

Offline rollatorwieltje

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #17 on: January 22, 2016, 01:35:50 pm »
@15:10 The second extrusion head would allow the use of support material, making it easier to print complex shapes. Instead of having to break away support structures, you can just dissolve it or peel it off (depending on material used).
 

Offline AF6LJ

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #18 on: January 22, 2016, 02:34:52 pm »
Looks really good......
Sometimes it's better to redesign from the ground up, this proves it.
Sue AF6LJ
Test Equipment Addict, And Proud Of It.
 

Online NivagSwerdna

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #19 on: January 22, 2016, 03:05:28 pm »
So much to like about this project... the mechanical eng is just sweet, the controller board thoughtfully generic, the choice of processor great for its QE, brilliant.

Not so convinced about the string<>number conversion stuff.  Why use strings at all apart from presentation to the human when necessary?  Just ship binary to/from the controller?  I also think it would be good if you can explain why the standard floating point conversions are slow... is it because they cater for locales, do lots of allocations etc?

You look really employable!  Great project!
 

Offline andreq

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #20 on: January 22, 2016, 03:45:46 pm »
Just.. wow!

Very good job designing all this by yourself David. I have my little RepRap at home and you're spot on with the "issues" about the controller and what not. I can't wait to see your lightweight extruder design up close.
 

Offline TheBlackOne

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #21 on: January 22, 2016, 04:20:45 pm »
First post for me!

David, awesome project. If it's like a Bachelor thesis from the amount of work: WOW, yes, you did SO much more than just enough to pass it. Awesome.

Regarding the clamping mechanism of the belt pulleys: There is something called Taperlock, doing exactly that. Gates sells their timing pulleys prepared for Taperlock usage. But: I did not check if they come so small as for your usage. They do go down to a 9mm bore for the axle.
There are other systems, too, like the "P-System" or SKF taper systems.


As for the optimized C++ string conversion code: std::stod is quite mighty in what it does under the hood, for example it takes care of the current locale for parsing, so it would work with both "3,141" and "3.141", depending on the locale set. Also, it copes with things like "3.14E9", removes trailing whitespaces and so on.
Here is an comparison about different ways to parse a string to double: https://tinodidriksen.com/2011/05/28/cpp-convert-string-to-double-speed/

Same goes for string to int conversions, of course: http://tinodidriksen.com/2010/02/16/cpp-convert-string-to-int-speed/

In that context: If you can be sure that your input format is fixed, a hand-optimized library will always outperform existing solutions.
 

Offline G7PSK

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #22 on: January 22, 2016, 04:33:19 pm »
Very nice work I particularly like the enclosure. Just wondering if it would be possible to put the filament drive motor on the main chassis and feed it through a duct in order to reduce the weight of the head unit, much like MIG wire feeders.
 

Offline TheBlackOne

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #23 on: January 22, 2016, 04:43:27 pm »
Ah one more thing:
David, if main target for the extrusion head is low weight: You could use smaller screws there (seems to me like M6, that's quite alot) and/or screws of another material. Aluminium would work fine for the expected stress/load, or even titanium? I guess Dave would switch to his "engineer p0rn" voice with titanium screws :-)
 

Offline Kalvin

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Re: EEVblog #843 - David's rPrint 3D Printer
« Reply #24 on: January 22, 2016, 04:46:02 pm »
About parsing the string data: Why not run the ASCII text through a preprocessor which would convert the numerical data into binary format - no real parsing necessary any more?
 


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