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Claystruder 2, Auger Paste Extruder

by unfold, published

Claystruder 2, Auger Paste Extruder by unfold Aug 5, 2012

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Description

Claystruder 2 is a prototype for paste extrusion that is build around a standard fairly lowcost disposable industrial auger extruder. This design is a testbed and not meant as an elegant design. Read about this extruder on unfoldfab.blogspot.be/2012/08/road-to-better-paste-extrusion-episode.html

Recent Comments

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You could look at the Dremel flex shaft for inspiration.
maybe changing this extruder so it fits an ultimaker..
need to have a flexible shaft to drive the auger
I see you are already working on thingiverse.com/thing:25195 Nice!

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Instructions

Please read this post on the auger extruder (and comments below) before attempting to build this extruder:
unfoldfab.blogspot.be/2012/08/road-to-better-paste-extrusion-episode.html

Things you need:

-disposable material path (the auger)
-HeadV1 5D.stl
-Auger-Stepper connector.stl
-Nema 17 stepper
-m8 washer (narrow one, OD: 16 mm)
-tape
-luer lock syringe
-Syringe Adapter Head (for example thingiverse.com/thing:21074)
-2x M3 30mm bolts & nuts
-4x M3 bolts
-luer lock tapered nozzles



I bought my DMP's at dosieren.de (http://www.dosieren.de/en/shop/products/cat/consumables/pr/disposable-feed-screw.html) but you can probably find them close to your place when searching for Techcon or OKI dispensing gear dealers. I used red and black ones and you can also find the steel augers there.

Print out HeadV1 5D.stl, this file has the two halves of the DMP housing. There is a slot halfway the housing where you can insert the washer, this washer prevents the auger from being pushed out of the DMP by the pressure of the material and the tendency of the auger to 'unscrew' from the material being fed. I also cut a small washer from reinforced ptfe sheet so there is less friction and wear on the auger. Insert the DMP in one half and test how loose it sits in the head when closed. Add some tape around the two ends of the T (top and side inlet) that sit inside the housing to make the fitting tight. Otherwise the DMP will wobble a during printing due to small imperfections in the alignment of the stepper and DMP. Now close the two halves with two M3 30mm bolts and nuts.

Print out one Auger-Stepper connector.STL, this is the coupling between stepper and auger. You might need to adjust it for your stepper shaft of file a flat on your stepper. Now push fit this on your stepper shaft. If all is well you can now screw the head on your stepper with 4 M3 bolts. The head was designed for a specific stepper shaft length that was perfect for me until I changed the stepper and the shaft was longer. I fixed this by printing a spacer that you can see in the pictures. You could also use long bolts and some alu tubing on each bolt as spacers. I lost the STL file of that spacer in a burglary.

Now you have a hand held extruder :) For the Rapman I laser cut a new carriage plate (file also lost sorry) that accommodates the extruder including a syringe. The screws that fix the head parts to the steppers went first through the carriage plate, then through the head and in the stepper (from the bottom up). Not very accessible but it was only a prototype to test the feasibility of using DMP augers.

The DMP from dosieren.de came with the nice elbow and extension adapter pieces for fitting a syringe so it sits upright parallel with the head. you can fit whatever type syringe you want, I use 50/60cc medical syringes and the adapter head that I have posted a while ago (http://www.thingiverse.com/thing:21074). But you can use smaller sizes or commercial adapter heads.

Now wire the stepper like you would with any stepper based extruder.

Pressurise the syringe so that it starts feeding the extruder but does not ooze out of the nozzle, that should be the right pressure. Always prime your extruder before using it. Now turn the stepper to check if it prints and find out the RPM.
maybe changing this extruder so it fits an ultimaker..
need to have a flexible shaft to drive the auger
You could look at the Dremel flex shaft for inspiration.
added instructions and BOM. Let me know if you build one.
Thanks for developing such great technology. I am looking forward to printing clay as well.

Idea: have you considered having the auger (and related parts) printed out of stainless steel/brass, glass or ceramic from shapeways? shapeways.com/

They charge by the cubic centimeter, and based on the size of the auger, I bet you could them printed out of metal for much less than 125
€. I bet you could get 5 for that cost. Stainless steel prints are $8/cc3 and ceramic is only $0.18/cm2, and glass is $6/cc3.

Or another possibility would be to print the auger out of PLA, then do a lost-PLA metal casting.
I was about to answer 'read our blog' on your previous comment but looks like you already did and changed the comment :) Jonathan came to us a while ago and we helped him get started.

In regard to your question. I did exactly that for my modifications of Ttsalo's moineau pump: thingiverse.com/image:117022

Would be interesting indeed to try it for a simple auger too, never considered that actually :) I lost confidence in the auger. But someone else should just give it a try. I think a 4-6mm diameter auger would be mutch more suitable then the 2mm ones in the DMP. Some people tried drill bits but failed, I think the pitch is way to low and depth of the auger too deep.
Note: I just ran across a parametric auger here thingiverse.com/thing:27854
thanks for the link! I will not spend more time on the auger design since I find more promise in the moineau type which is only sligthly different (and more complicated). But I encourage anyone to get a shot at a fully 3d printed auger design. It might just work.
I see you are already working on thingiverse.com/thing:25195 Nice!
I read your blog post with interest.

I hope you manage to crack the nut on clay printing. Hopefully without having to resort to the 2500 dollar augor...

Kudos for the effort!
we're much closer to that actually but I am documenting all past research and this is from last year. The moineau pumps around here on thingiverse are good examples of how to improve the auger based design towards a true positive displacement pump.
I suggest some lateral thinking here - what if a type of "Bubble" printing mechanism can be used to extrude the material?

With other words use a blower to force the material out of the nozzle (In the building industry an air pressure pump is used to spray mortar or papercrete onto the build surface - youtube)
Well, damn. A motor connected to an auger, that's about as direct-drive as you can get, I wish I'd thought of that.

Looking forward to seeing how well this works :)
More questions:

1) McMaster Carr sells this air dispensing syringe adapter. Have you considered using it on your syringe instead of the printed syringe adapter?

mcmaster.com/#syringes/=iqscxo

The only limit I can see is that it only does max 35cc
You can use whatever you want, the auger has a luer lock connector so you can feed it from whatever size syringe with whatever adapter cap you want as long as it has luer. I like standard 60cc medical syringes that I can get from the pharmacy around the block instead of often more expensive industrial syringes for which these caps are (different diameter). And we have a printer so why not print the adapter?
Any idea whether this will work with play dough? I'm not sure what the viscosity of your clay is.

Could you put together a bill of materials?
bom and instructions added
Never tested play dough but as a general rule, if you can manually squeeze it out of a syringe without hurting your fingers, you'd have a good chance it extrudes.

The BOM and instructions will follow when I'm out of the woods and out of EDGE network range ;)
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