Status: version 3.1, beta testing
View 3D CAD file: https://wikifactory.com/+fabmxteam/fabmx/file/PelletExtruder/Version3.1/PelletExtruderv3.1.step
Github repository: https://github.com/ProjectFabMX/FabMX_Extruder
BOM
| Item | Amount | Description | Source of supply | Comment |
|---|---|---|---|---|
| Extruder Screw | 1 | extruder screw | custom part, steel, drawing/parameters | |
| Extruder Barrel | 1 | includes mount and water cooling channels | custom part, steel, see step file | |
| Nozzle | 1 | standard 3D printer nozzle, type E3D V6 1.75mm; optionally hardened | e.g. https://e3d-online.com/products/v6-nozzles?variant=40924117598267 | Typical nozzle diameters are 0.4 or 0.6mm |
| NEMA 23 Stepper Motor with gear box | 1 | see notes below | ||
| Shaft Coupler | 1 | rigid shaft coupler 10mm to 12mm, D=max30, L=40 | e.g. [dold-mechatronik.de] or [aliexpress.com] | do not use flexible couplers, they cannot take axial load |
| Heating cartridge | 2 | 40W, 24V, 6mm x 30mm | ||
| Metal Cage | 1 | several laser cut aluminum parts | custom parts, aluminum 3mm, laser-cutting folder on github | |
| Pellet Inlet | 1 | custom part, PLA/resin, 3d printed, see github | ||
| Pellet Tank | 1 | custom part, PLA/resin, 3d printed, see github | ||
| Temperature Sensor | 1 | standard thermistor for use with 3d printer controller board (e.g. 100K NTC) | ||
| M5x110 | 4 | DIN-912 | ||
| M3x8 | 4 | DIN-912 | for attaching the inlet to the lower aluminum plate | |
| M3x20 | 2 | DIN-912 | for connecting pellet inlet and tank | |
| M3 brass insert | 6 | e.g. [cnckitchen.store] | ||
| Pneumatic fitting G1/8" | 2 | Fitting G1/8" for 4 or 6mm tubing | e.g. Festo QSML-1/8-4-100 | for water cooling, use tubing size to fit your cooling system We recommend liquid thread sealant |
| Closing plug G1/8" | 1 | Closing plug G1/8" hex socket | e.g. [landefeld.de] | We recommend liquid thread sealant |
To run the extruder you will also need a water cooling system:
- the best (and also most expensive) option is a industrial water chiller
- Another good option is a PC cooling system, including pump and a radiator
- Alternatively just use a cheap aquarium water pump. If you have a big water reservoir (>3 liters) you can also skip the radiator
We are currently mainly using PolyMIM materials, as these feedstocks can be debindered easily in a water bath. See DIY 3D Printing with MIM Feedstock for tips on using the extruder for 3d printing.
Motor/Gearbox
The extruder uses a NEMA23 stepper motor with gear box. It needs to have the following specs:
- The gear box needs to have 4 M5 threaded holes for mounting, lying on a circle d=45mm
- The gearbox shaft should have a diameter of d=12mm. Use a different coupler if the shaft has a different diameter
- The gearbox diameter should be D=56mm or smaller
- The length of the motor and gearbox are noncritical for the design. Typical sizes are L1=60mm and L2=56mm
- The gear ratio should be in the range of 1:15 to 1:47. A gear ratio of 1:28 seems to be a good compromise, but is hard to get
Sources of supply:
- https://de.aliexpress.com/item/1005003850399817.html
- https://www.omc-stepperonline.com/nema-23-stepper-motor-bipolar-l-56mm-w-gear-ratio-15-1-planetary-gearbox-23hs22-2804s-pg15
- https://www.omc-stepperonline.com/nema-23-stepper-motor-bipolar-l-56mm-w-gear-ratio-47-1-planetary-gearbox-23hs22-2804s-pg47
Size/Mounting Holes
Assembly Notes
- The aluminum plate directly above the barrel needs to be manually adjusted to create a smooth transition between the hopper and the barrel inlet. For this, chamfer the edges with a file.
- The left and the right side aluminum plate are similar, but not identical. The 3d printed inlet only fits in one of them.
- If you want the inlet to be on the right side instead of the left side, you can do that without modifying the parts, they are symmetrical.
- For the water cooling parts:
- The barrel includes channels for water cooling. There are 3 openings: the 2 next to each other are inlet / outlet, the 3rd one needs to be closed
- For inlet and outlet install a G1/8" fitting for 4 or 6mm tubing. Choose the tubing size that fits your cooling system (or use an adapter)
- Use a G1/8" closing plug with hex socket to close the 3rd hole
- We recommend liquid thread sealant to make the connections water tight
- At the backside of the barrel tip there is a M3 threaded hole. This is intended to mount your temperature sensor. If you have a glass body type thermistor, use a soft (e.g. PTFE) washer backed by a standard (metal) washer to hold it down to prevent damaging the sensor.
- There are two 6mm bores in the barrel tip for inserting standard 3d printing heating cartridges. They usually stay in place without needing anything fastening. Use a punch near the bore if the cartridge is loose.
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