New extruder

This weekend was kinda productive, without getting anything done… kinda

I have been working most of the weekend on a new extruder, using a cheap geared stepper motor.

The first thing was to make a drive gear with a 5mm hole and hobbed grove so it could push the filament through the extruder.

I then had to design a new extruder house and print it out on my old, but reliable, wades extruder. And after one mistake and a new version, it was ready for use!

What I quickly discovered, was that this motor is a unipolar (knew that all the time :P), and by not using the middle wire between the two coils, it would only shake not spin.

After some swearing, some more swearing, then deciding to stop trying, and then decide that it would not get away that easy,  actually got it working by only using one of the two coils.


I then had to do a bit testing on how fast it could move, and also get the E-steps calibrated.

Here we are! Ready to print!

The next problem was then heat… a lot of it…

When looking at the Chinese (I think it is Chinese) datasheet, it says something about 6V and 12V, and 12V isn’t enough to make it move when using both coils. I think the heat is being that high because I am putting 12V into a coil which maybe only should have 6V.. hmm, anyways… it spins… let’s move on and cool it down!

So I added two fans, a 60mm and a 120mm, both spinning at full speed, and SUCCESS!!! I am printing with it!

But there was still some small problems, one was that the extruder house was bending a bit while printing, so that got fixed with an extra support, and one bolt could still not go in..

.. so after a bit more design changing, it was time to print a new extruder house!


And everything seems to work just fine. After making this little video I put the 60mm fan back on, and let it continue to print.

… or I let it print for around an half hour, then started to play a bit with the print speed.

When I sliced the stl with Slic3r, I had set it to 90mm/s, and I then used M220 S200 in Marlin to set the feed-rate up to 200%, and the result was this

Sadly this was the last print it made, the heat from the motor again got too much for it, and the extruder house started to bend.

I might pick up on this again later, or some of the other folks on #reprap on freenode might… Stay tuned! If we get this to work properly, we will be looking at some cheap geared stepper motors, which also are lighter than a non geared Nema17 motor.

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