Sunday, January 02, 2011


Belt drivn extruder

It occurred to me recently, after building two mendels, and printing way too much (including one of those mendels), that the weakest harware point in my Mendel was the gearing on my extruder/s.

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.

From Reprap

and a youtube link to it printing:


Nice work, although it sounds like your printed gears are more troublesome than usual - I've got over 5 Mendels printed on a single set of extruder gears, and Nophead has something like 100 + Mendels printed, although I don't know if that's all from the same set of gears.

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?

I am on my second big gear and third small gear on my Wade's extruder. The teeth on the first small gear wore out fairly quickly because I didn't lubricate them. Since I added lithium grease they have lasted a very long time.

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.
Your extruder doesn't seem to reverse on the video. Do it not leave strings?
Anybody try the herringbone gears here?

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.
And Extra friction due to belt tension.
tillin9 - I have been printing some of those Herringbone gears, (Rhys Jones Herringbone) just assembling them onto an extruder at the moment.

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.
Wade: I've been ( and still am ) using "Adrians" extruder/s, on all 3 mendels I've built or helped built. I'm also using a 0.6mm on the main production printer nozzle, which is admittedly large.

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: )
Post a Comment

<< Home

This page is powered by Blogger. Isn't yours?

Subscribe to
Posts [Atom]