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Moineau stepper extruder

by ttsalo, published

Moineau stepper extruder by ttsalo Jan 6, 2012

Description

Paste extruder based on the Moineau pump principle.

The pump geometry is based on thingiverse.com/thing:7958

Should work as a plug-in replacement for a hot plastic extruder in a 3D printer. However, I have NOT used this to actually print anything. I'm just publishing it in case someone else wants to try it out. (I think it's ready for printing a very small pizza without toppings, but beyond that I cannot say.)

Almost everything is parametrized and adjustable from the SCAD file. However, the resulting design should be evaluated to see if it is still sane after adjustment, since not all of the features are automatically calculated. Particularly the flange and driveshaft diameters must be adjusted by hand to match the other measurements.

See it in action: youtu.be/OHQiKuQvuEU

Note: obviously it is impossible to build an object from material that flows on it's own - the object would not hold it's shape. So in practice the material has to either be pulled into the extruder by a negative pressure (impossible with PLA printed pump parts) or pushed into the extruder by a positive pressure. In either case the motor axle has to be sealed, or it would either relieve the negative pressure or allow the material to flow up and out from the inlet block.

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The mathematical model for generating the pump geometry was created by emmett for this: http://www.thingiverse.com/thi... thing. He can probably explain it better since he wrote the original.

If you need a pump with different geometry, you can modify the parameters in the scad source file and re-export it from OpenSCAD. The sources are included in both this and emmett's original design.

Hi, recently printed this model on an Objet 250 using clear resin and assembling now. Do you have the original CAD file (possibly not willing to give away), or can you explain the math behind your rotor/stator. I wish to design a very very small pump and am having issues with the math. Many thanks, Chris.

The derived chocolate extruder has instructions on how to set up the software for printing:
http://www.thingiverse.com/thi...

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Instructions

Print plastic parts. Cut flange seals from thin rubber (I used bicycle inner tube). Assemble with M3 nuts and bolts, adding a NEMA17 stepper motor. Fill inlet tube with material to be extruded and start the stepper motor.

There is a seal retention ring near the motor mount inside the inlet block, so that the motor shaft can be sealed with some kind of a seal. With this done, the inlet tube may be made thinner and a flexible tube connected to it for feeding the extruder from an external pressurized reservoir. (This part is still work in progress.)

Comments

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ChrisBTW on Aug 29, 2013 said:

Hi, recently printed this model on an Objet 250 using clear resin and assembling now. Do you have the original CAD file (possibly not willing to give away), or can you explain the math behind your rotor/stator. I wish to design a very very small pump and am having issues with the math. Many thanks, Chris.

ttsalo on Aug 29, 2013 said:

The mathematical model for generating the pump geometry was created by emmett for this: http://www.thingiverse.com/thi... thing. He can probably explain it better since he wrote the original.

If you need a pump with different geometry, you can modify the parameters in the scad source file and re-export it from OpenSCAD. The sources are included in both this and emmett's original design.

abferm on Aug 7, 2013 said:

I want to try setting this up for support material extrusion. What settings do you put in the printer firmware to get this working correctly?

ttsalo on Aug 7, 2013 said:

The derived chocolate extruder has instructions on how to set up the software for printing:
http://www.thingiverse.com/thi...

misan on Aug 4, 2013 said:

Is there a reason for the nozzle not be a part of the same stator piece?

ttsalo on Aug 5, 2013 said:

It's just to make cleaning the inside of stator easier. If that isn't a concern, they could be combined into one piece.

Andrew1618033 on Jul 18, 2013 said:

What's the material in the video?

ttsalo on Aug 5, 2013 said:

It's a mixture of water and wheat flour.

Anonymous on Sep 12, 2012 said:

hi there very interested in your work with chocolate--hows it going? what adaptions did you have to make? what sort of things have you tried to print in chocolate? sorry could go on for ever

unfold on Feb 24, 2012 said:
unfold on Feb 1, 2012 said:

Added a simple luer-lock to the nozzle part: http://www.thingiverse.com/thi...

unfold on Jan 31, 2012 said:

What kind of seal do you use to seal the motor shaft? Did you cut this from rubber also? I am intending to used a pressurized syringe on the inlet side so will need to seal that end well.

Do you have an updated version otherwise I start drawing some new parts so it uses more Luer lock connectors. I would redo the nozzle end with a lure lock connector salvaged from a syringe, that way there is no need to replace that end, just screw a new tip on it.

unfold on Jan 23, 2012 said:

Hi ttsalo,

We have done some extensive experiments with porcelain and other ceramics in the past using time-pressure type extruders: http://www.thingiverse.com/thi...

Last year I spend a lot of time trying to improve this system and came to the conclusion that the real way to solve a lot of the issues w
as by having a metered progressive cavity pump that does only use air pressure to assist the clay into the pump. Before this I had high hopes one a prototype I build that worked with an auger but that didn't work out because it has one continuous cavity (loooong story). So last month I came to the c
oncluding after diving into papers and websites and more websites that the moineau pump could be a great candidate but my educated guess was that it would be impossible to prototype yourself. Looks like you made one and proved me wrong :)
It will probably grind down by the abrasive nature of ceramic
clay but what if we let shapeways make one out of metal and maybe the stator out of some more flexible material? I will print this one next week and for the just give it a shot with porcelain.

Super cool job you did!

Whitt on Jan 16, 2012 said:

How feasible would it be to mount one of these on the carriage beside the other extrude and print water soluble support material while printing the rest of the model. It would allow a far greater range of shapes that could be printed.

Unfortunately I'm still making my printer so I cannot give it a go yet.

caster66 on Mar 9, 2012 said:

The biggest catch with the water soluble support would be set time unless the paste is rigid enough to be able to print on.

As a side note this pump could be used for UV curable pastes as well. Just extrude the paste then expose to UV source to cure. There is some UV curable pastes used for automotive work available on amazon that can cure with just sunlight. Use a UV lamp or LEDs instead and speed up the cure and you
can make some nice, rigid printed objects without needing to bake them like you would with ceramics.

ttsalo on Jan 19, 2012 said:

It's perfectly feasible, but you would have to make the print carriage bigger and heavier. It would affect print area and printer performance.

I'm developing a version that prints chocolate right now. I already extruded some with model V1 and my printer is printing V2 as I speak. I'll upload that as a derivative as soon as I get some (hopefully impressive, but at least tasty :-) ) real-world results out of it.

qharley on Jan 7, 2012 said:

For a seal, may I suggest the silicone compound commonly marketed as "Gasket maker"

You basically leave a groove on both sides for the gasket maker, squeeze it on and almost tighten the seal. Wait for it to dry and tighten it all the way.

I'll be adding one to my Repstrap (if I can only get time to build the thing to begin with...)

ttsalo on Jan 8, 2012 said:

That sounds like a good idea. I was already thinking of trying to find some sort of elastic stuff to make a seal before going for serious things like O-rings, X-rings or lip seals. In extruder use, the RPM is going to be very low so it should not need a high-performance seal.

polymaker on Jan 7, 2012 said:

Great work, this is huge! I can't wait to print some clay pots with this!

Gene_Hacker on Jan 7, 2012 said:

Great work! It'd be interesting to see if this will work with ceramic paste.

tetnum on Jan 7, 2012 said:

printing i have a cupcake that i could try and make this work on

emmett on Jan 7, 2012 said:

Awesome! I was thinking about trying to motorize mine and now I don't have to. I can't wait to see your printed pizzas.

Zomboe on Jan 7, 2012 said:

It just occurred to me that this type of extruder has huge advantages for self replication over the traditional hot end. If you could use it to extrude a material with the right properties for making the printer's structure parts (including this extruder itself), you'd significantly reduce the vitamin count and cost of a RepRap.

I guess the biggest issue is attaining the level of accuracy required, along with finding the right material for the job.

tbuser on Jan 7, 2012 said:

Looks nice! Is there a reason you made it in 3 parts with seals? It looks like with a few small changes you could print it all in one part.

ttsalo on Jan 7, 2012 said:

The idea is that there would be a waterproof seal for the motor axle in the top of the blue part, so the rotor and driveshaft have to be assembled from below, meaning that it has to come apart around where the conical flanges are.

The nozzle and the stator (the red twisty part) could easily be a single part, but then it would be very hard to clean them and you couldn't change the nozzle to a different size.

Zomboe on Jan 7, 2012 said:

I can see the benefit of having a removable nozzle, but you are probably right about the other two parts.

For the first prototype making it in separate parts may have made it easier/quicker to tweak and iterate the design.

Actually, now that I think about it, maybe the red twisty part would require a better tolerance or finish and could benefit from being printed with finer, slower settings.

Zomboe on Jan 7, 2012 said:

Awesome work! The design is very visually appealing. I like that you made the parts in different colors :).

I look forward to seeing this in action on a 3D printer.

ttsalo on Jan 7, 2012 said:

I'm also very interested in seeing how (if) this actually works, the problem is that I'll have to build a second 3D printer first :-D

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