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

Compact Extruder for 3mm filament

by BoByS Oct 11, 2015
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very nice compact will try later on hot end
thankx

same for 3mm nut.... one must allow for plastic tolerances during printing i find an additional .2 or .3 is usually necessary
or one has to mess around with a file...in general test your designs....we all get so excited to publish our latest designs

Hi, Vvdd. Thanks for the feedback. Every design I'm publishing is tested by me, on my printer. However, I have tested this extruder with a different printer (the one we have in our office - pretty rough tolerances) and I'll print it with my printer to see what's going on. For the print I've made, no files were required for the M3 nut-trap. I'm usually making the mounting holes as per DIN standard (notice that the printers are in 0.2-0.3mm tolerances. For example with my printer: 3.5mm hole will be closer to 3.2mm) because I found that it's better to pre-drill them with the proper drill bits after the print. This saves me a lot of headaches during the assembly.
I've made the design 5 or 6 months ago... Still waiting for the first tests. That's the reason why it's still "Work in progress" and the reason why there is no real picture of a print here. The 3D printer for that extruder is almost ready, though...

the bearing shaft is .2 to big the designed shaft has to be filled a bit to accept a 608 bearing

Hi there, nice design!

Which type of stepper motor are you using? NEMA17? Does it have enough torque to push 3mm filament without gear reduction?

Hi, Tech2C!
My motor is NEMA17 - 42BYGHW811 - 4800g-cm /// 2.6A /// 1.8 deg/step.
The first test was to push the filament. It was pushing it with no effort. The motor and the stepper driver was cold due to process. I just make it pass thru the extruder. I've made some test with the bearing close or far from the MK7 drive gear and I think I found the place that it's most efficient. I tried to measure the pushing force and it's between 200 and 700 gr (pretty rough but...electronic scale for the win!). Only the spring must be stiff. I'm using a spring from IKEA clothes pins (they are pretty stiff).
Notice that I still didn't test it with a hotend. I am building a Delta printer (more than 200 cm tall - 500x500x1000 building volume) for a friend and I plan to use this extruder for it. When his hotend come, I'll test everything with it.
On my standart Prusa i3 I already put your extruder! Nice project and I'm really happy with the results. I upgraded my printer with 1.75mm filament.
Best regards and keep up the good work!
Bobby