Sunday, January 02, 2011
Belt drivn extruder
They always seem to have problems.
I have problems with:
*printing the teeth nicely/accurately,
* getting the teeth to mesh,
* keeping them meshed over time,
* teeth wearing out or getting "chewed off"
and the resulting printing issues these cause!
So, I thought "I don't have issues with the XYZ axes anymore, so why not use the same principle/s on the "E" axis.?
Result: A belt driven "adrians" extruder.
I took a random "big" cog for a belt, and a semi-random "small" one ( ie matching), and put them on one of my extruder/s. It's awesome! I haven't "skipped" , or chewed a tooth or anything in ages!. It was a little fiddly sewing the belt together ( with a needle and thread ), but that's just because I'm too cheap to buy one the right size.
and a youtube link to it printing:
Labels: belt driven extruder
The gear design on my extruder is a lot more conservative than Adrian's though - were you having trouble with Adrian's geared extruder, mine, or some other design?
The second little gear broke where the captive nut is when it came loose and I overtightened it. I replaced the first big gear at the same time as I noticed backlash had increased. It had been initially run with no lube though.
I think they last amazingly well for ABS gears with so much torque on them.
The increased thickness should help with strength issues both by being bigger/ stronger and distributing the load over a larger surface and the constant contact would help with backlash/ ooze issues.
Thinking the only downside might be the added mass.
It's a Nice Idea to use belt drive, I wonder if you could make it auto-tension and mount the motor somewhere above the extruder drive (belt-driven remotely?) - probably not.
Nophead: In the video I was actually using a developer version of repsnapper to drive the extruder, hence no reversing ( repsnapper has it, but its buggy). In practice, reversing works well anyway.
RichRap: adding a real belt tensioner is theoretically as easy as adding a spring-loaded idler wheel.
( perhaps a smaller version of something like this: http://www.oocities.com/watch_crazy/Jbww2/mods/tension2.jpg )