Uploaded October 2024 | Updated September 2026, 1 week ago
SLM printed worm drive extruder- initial print after assembly
This is a 15:1 worm drive using a 2 start worm and a K1 extruder gear. Interestingly, this arrangement puts the extruder motor on it's back, lowering the center of mass and taking the motor heat to the base toolplate and to the extruder frame.
2.8 rotation distance (~1100 steps per mm). Moons CSE14HRA2L410A-02
Initial tests with plastic and 17mm LDO motor was ~50mms3 flow. However, there was some additional friction in the hob gear. I will go back and test the 17mm against the 20mm Moons motor. The 20mm Moons tested up to 85mms3, but to be fair I didn't run the test past 87.
The filament path was not right. The edges were shaving the filament and making powder. I went in twice and re-shaped the top and bottom of the guide. Using small dremel with round tip bits and then some valve grinding compound on a piece of filament, in and out.
There were 2 surfaces that are dimensional critical that were off ~.35mm one dimension and .25 in another. So with SLM, give yourself some leeway on design so you know where it might matter if things go wrong.
Thermals of the extruder is really good at ~42-45C on the extruder body. Much better than the 100C+ temps I had with plastic and melting.
Assembly is really easy for this one. The cat's meow is the jack screw in the back to set the worm lash. This works like a charm and repeats when the motor is removed. This ensures that when tightening the motor it does not walk into the hob gear.
BTW, that little 20mm moons motor is 101.3 grams!!!
Tested flow at 85mms3(ABS) with .4TC nozzle, 20mm Moons motor vs 50mms3 with plastic and 17mm LDO.
So, why worm you ask? I was sucker punched into doing it!
Worm has some advantages and disadvantages. The hob gear is not able to be backdriven, so pressure buildup in the hotend does not make it back to the motor to cause slip. The extruder gear runs on a bearing that is concentric. So as long as you have a quality made gear, your extrusion quality should be better. It does need more speed to run for the same extrusion, so the motor can run out of torque to drive it. Not able to load filament by hand due to cannot rotate the extruder gear (auto load only).
I will be testing this rig, making some changes to the CAD and making a Rev1.0.
SLM printed worm drive extruder- initial print after assembly
This is a 15:1 worm drive using a 2 start worm and a K1 extruder gear. Interestingly, this arrangement puts the extruder motor on it's back, lowering the center of mass and taking the motor heat to the base toolplate and to the extruder frame.
2.8 rotation distance (~1100 steps per mm). Moons CSE14HRA2L410A-02
Initial tests with plastic and 17mm LDO motor was ~50mms3 flow. However, there was some additional friction in the hob gear. I will go back and test the 17mm against the 20mm Moons motor. The 20mm Moons tested up to 85mms3, but to be fair I didn't run the test past 87.
The filament path was not right. The edges were shaving the filament and making powder. I went in twice and re-shaped the top and bottom of the guide. Using small dremel with round tip bits and then some valve grinding compound on a piece of filament, in and out.
There were 2 surfaces that are dimensional critical that were off ~.35mm one dimension and .25 in another. So with SLM, give yourself some leeway on design so you know where it might matter if things go wrong.
Thermals of the extruder is really good at ~42-45C on the extruder body. Much better than the 100C+ temps I had with plastic and melting.
Assembly is really easy for this one. The cat's meow is the jack screw in the back to set the worm lash. This works like a charm and repeats when the motor is removed. This ensures that when tightening the motor it does not walk into the hob gear.
BTW, that little 20mm moons motor is 101.3 grams!!!
Tested flow at 85mms3(ABS) with .4TC nozzle, 20mm Moons motor vs 50mms3 with plastic and 17mm LDO.
So, why worm you ask? I was sucker punched into doing it!
Worm has some advantages and disadvantages. The hob gear is not able to be backdriven, so pressure buildup in the hotend does not make it back to the motor to cause slip. The extruder gear runs on a bearing that is concentric. So as long as you have a quality made gear, your extrusion quality should be better. It does need more speed to run for the same extrusion, so the motor can run out of torque to drive it. Not able to load filament by hand due to cannot rotate the extruder gear (auto load only).
I will be testing this rig, making some changes to the CAD and making a Rev1.0.
