Nema17 Peristaltic Pump

This is a DIY peristaltic pump that is driven by a Nema17 stepper motor. It uses a 10 mm x 6 mm (AD x ID) silicone tube to transport up to 1 L/min (or more) of liquid.

Parts needed to build this pump (provided links are just examples):

1. 1x Nema17 stepper motor (I have used a 40 mm long one but any works)
2. 6x 625ZZ bearings
3. 4x M3x4 heat inserts (4.5 mm outer diameter)
4. 3x M3x16 hex screws
5. 8x M3x6 hex screws
6. 4x M3 nuts
7. 1x 10 mm x 6 mm silicone tube

First you need to print one of each of the provided files. For me the fitting on the motor shaft was quite good, if it is too tight or too loose you might need to tweak your print settings.

You will also need to add normal supports since the screw holes do have overhangs that need to be supported. However these are not critical surfaces that need good tolerance and will not be seen later on. Appart from the screw holes there are no suppoerts needed.

I have used 0.2 mm layer height, 15% infill and 3 perimiters. I printed all parts in PETG but PLA should also work. But PETG offers better flexibility and is less prone to breaking.

The next and also the last step is the assembly. The explosion view shows where each part needs to go.

1. Insert the four heat inserts into the corner hole on the top of the base. Mount the base to the stepper motor in the orientation that you want using four M3x6 screws.
2. Insert the three M3 nuts into the bottom of the motor mount
3. Mount the 6 bearing (two on each pole of the motor mount), close it off with the top cover and use three M3x16 screws to screw the parts together (see explosion view of the motor mount assembly)
4. Push the motor mount assembly onto the motor shaft. Mind the orientation of the flat side of the shaft. Push it down as far as it goes.
5. The Assembly was constructed for a motor shaft with a length of 22 mm (from face of the motor to the end of the shaft) If your Nema17's shaft is longer or shorter you might need to change the parts or add a washer of some sort.
6. Insert the silicone tube by turning the shaft and pushing it in beginning one side and moving over to the other end.
7. Next you need to close the lid. I have found, that the motor can struggle with the tight fit of the tube and might stall. For me it helped to let the motor run and with the tube inserted but without the lid. The while it is running close the assembly with the lid and screw in the remainign four m3x6 screws.

Your are done building your DIY Nema17 peristaltic pump. If you want to push the pump to it's limits you might find that the motor stalls if you go from zero to full speed right away. However you can start at half speed and increase it in small steps but fast to prevent it from stalling.

I was able to reach 1 L/min with this method however I also needed to use a bit more than 12 V of supply voltage for the motor. Of you are using larger Nema17 versions you might be able to increase the flow rate even more.