Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Chocolate pump

by Ioan, published

Chocolate pump by Ioan Mar 11, 2012

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Chocolate pump by Ioan is licensed under the Creative Commons - Attribution license.

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This is a gerotor pump type. It is designed to pump viscous fluids like chocolate, glazing creams, epoxy etc. It is still under testing, next version will have an NEMA 17 stepper motor atached.

An option is to laser cut in plexiglass the entire pump body making it food contact safe.


Print parts. Sandpaper carefully the outer rotor and outer rotor housing such that they will rotate buttery. Sandpaper the contact faces of bearing housing, rotor housing and ports housing. It is important that all pieces to make smooth contact. Cut gaskets from some soft rubber and mylar. Obviusly everything must fit perfectly to stop leakage.

Additional items: 1 x 606 bearing, 3 x brass tubes (6mm OD, 5 ID) and 5 x M3 nuts and bolts. Two of the brass tubes are used as hose adaptors and one for bearing axis. Also you will need one M5 bold which accomodates the inner rotor and is used to transmit the torque to the rotor.

Air, water and any other low density fluids will not be pumped because ABS or PLA are too porous and tolerances cannot be made very small. However viscous fluids like chocolate are well pumped. Such kind of Gerotor type pump can achieve high pressure.

Thinner the inner and outer rotors less volume will be pumped so it is easy to design very low volume pumps as needed in precision fluid delivery.

Attached is 3D pdf file so you can better inspect the pump.

Also this pump can be made out of plexiglass by laser cuting the parts. Dxf files will be posted soon.

Pay attention to the ports. They should be somehow made "waterproof". Even solids can penetrate in the porous ABS. I am using some paint now.

Hey guys! A tip to smooth the rotors out! I have pumped a mixture of water and Ceramite (a kind of ceramic powder used to make moulds). Guess what? Every piece of the pump was sanded smooth. Wash, dry and oil the 606 bearing ;)

In search of a "silver bullet" gasket: low shore silicone+adhesive PTFE foil to reduce friction. Any other ideas? :D

I have changed the gaskets.dxf file. The scale ratio was incorrect. Now fixed. Units: mm

Solved with pump sealing. I have painted the ports gallery, ports housing face and bearing housing face with some nail polish (acetone based). So there is no more porous material. Gaskets were cut from PTFE coated textile self adhesive material. PTFE is an excellent dry lubricant and has good wear resistance. The only spot were air could enter in pump body is between M5 bolt axis and the brass tube holding the M5 bolt. This was solved with some soft rubber o-ring.

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PTFE (or Teflon) is a bad idea! Pieces of it could break loose, then it's in your food. Teflon may be okay on your pan, but not in your food.

I was wondering how you designed the gears? Did you copy them from some source or did you draw them yourself? I would like to draw/design my own (with different amount of tooth) but I can't seem to find the theory behind the geometry, or am I thinking too complex? Should I just start drawing and tweak the geometry till it fits nicely?

Hi, the pump is designed with this software: http://www.maverickracing.co.uk/gerotors/
It can be used for free for 30 days.

Great, thanks!

THANK YOU THANK YOU THANK YOU.... for the dxf files.. The rest is very easy to redo with a laser cutter.

Any chance of uploading the 2 main gears (inside and outside) in DXF format as mentioned? Thx much.. and to Frollard.. use a crayon for the wax to lube?

Hi loan, do you have any video of this in use?

No. My chocolate pump and cooler are stopped due to lack of time. Sorry... :)

I am going to build my own chocolate waterfall that flows over edible
rocks and into a pond, but I need a pump for pushing the water out and
taking it upstream. Does anyone know where I can get just a small pump
to do this?

I made a plexiglass version on the laser cutter and its pretty spiffy but we didn't use a bearing and the tolerances are hard to make it mesh nicely - tried pumping liquid soap as a lubricant and it works but with no gaskets it leaks like a sieve! very promising though!

If only this can be used to pump out melted plastic!

Well, it's good enough we have pretty simple extruders thanks to the wonderfull people who made this possible. I am still dreaming to a simple extruder to lay down other materials than plastic. ;)