Herringbone Geared Extruder
Description
As the name suggests, the design uses Herringbone gears. This ensures that backlash is substantially reduced, which should result in the extruder requiring slightly less reverse, but more importantly run quieter. The design of the drive gear is somewhat experimental. As with other gears, this uses a grub screw to secure the gear to the motor shaft. However, on this design the hole goes through the root of one of the teeth. This takes up less space, and also lets you adjust the position of the gear without taking the motor off. However, it is quite intricate. Many people have managed it, but your printer needs to be running well to do it.
Instructions
Also, on my pictures the layout is not optimal. Ideally I think it should be Gear, 3X Washers, Spacer, 2X Washer, Bearing, Gap, Bearing, Washer, 2X m8 Nuts. It might be an idea to increase the size of the spacer, and do away with some washers, but I personally like that it allows some adjustment in either direction.
The final two nuts do not need to be done up tightly, doing so would mean the bearings become a little rough. The herringbone gears should keep everything aligned by themselves and the bolt takes all the torque, so the nuts only need to be lightly tightened.
When assembling this extruder, it is somewhat critical the gears are perfectly aligned. Herringbone gears try to self-center, if the alignment is incorrect they'll probably get damaged. I find the best way is to assemble everything, not tightening the grub screw on the drive gear, give the whole thing a couple of turns during which the gears should align, and then tighten the grub.
On my photos you'll notice I've used m4 nuts to tighten the idler. Ideally, you should use wing nuts instead as these allow you to adjust it by hand.
13/12/10 - Updated Idler to beef up the filament guide
18/12/10 - No design changes, but the STLs have been simplified to ease slicing.
06/01/11 - Updated drive gear holder to reduce the holes for the bearings to give better constraint. You may now need to press fit them in, or give them so encouragement with a hammer. Fortunately the bearing supports are open and therefore can flex a little to hold the bearings tightly. Also I've uploaded a new idler bracket without the filament guide, I don't think its actually needed with a hobbed bolt. It seems to be printing as well without it anyway.
02/02/11 Updated the driven gear so that the herringbone gears now contact in the recommended "stable" manner. If you already have this extruder and want this, you only need to print the driven gear, and then just flip the drive gear. Also the idler bracket has been updated for better placement of the holes. I've uploaded updated IGS & STEP files for those who use them.
15/02/11 I've pulled some of araspitfires updates into the main release as they are much better:D. Also thanks to bobbens, all the STLs should now be orientated correctly for skeinforge users.
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Do the mounting holes and the location of the filament hole still fit the Thing-O-Matic or are the versions >july 2011 Reprap specific?
I made one, but with the springs I have (from a INTEL Cpu cooler) it's impossible to load material into the thing - it's just too tight between the bearing and the bolt. So I loosen the screws to get the filament in to the pinch, and then have to re-tighten the 4 spring screws to make it hold firmly....
I finished building my copy of this thing last night, for the record I printed the gears in PLA on a Mendel with 100% infill and the small gear printed fine. The main problem I had was with the driven gear, if it's even slightly warped due to printing without a heat-bed or printing with less than 100% infill then there's a chance that the bolt won't sit perfectly straight. If that happens then the gear wobbles slightly as it rotates...not a big deal with standard gears but a big problem with herringbone ones thanks to their self-centering nature.
I also had a problem mounting this on Buback's OpenX carriage (thing #6278). The driven gear dips slightly below the base of the main block which limits the number of alternate carriages it can be mounted on.
Overall though this is a great extruder, a bit more finicky to put together than the ot
hers I've built but a very sturdy design and the best one I've made so far.
Definitely the coolest thing we've printed so far here at PSU :D Check it out: http://reprap.org/wiki/Etherda...
Yay! I can't wait to finally solve the bloody repsnapper issue I'm having to be able to print the last part and finally mount the sucker :).
I'm using the free rhino 5 beta and it seems to be lacking STEP support although rhino 4 can do STEP, maybe I'm being stupid somewhere. Would you mind uploading in IGES? I've had luck with that in the past, it would be nice if there were a universally good format
I was wondering if your Herringbone design may start off a leadscrew or direct drive approach. A horizontal fitting drivetray may evolve and replace the belt on X altogether. Nice work by the way, I like very much the drawing you made.
Awesome! Is it actually working as well as the original Bowden/Wade versions?
It seems to be. I've only ever used Adrian's but I'm getting equally good results. Araspitfire claims he is getting equal results to his Wade's. I think the bearings could do with being a little better constrained though. Araspitfire did a fix which helps that I uploaded (thing 5134), but when I get a sec I'll do some thing more elegant.
Could someone make an Imperial version of this? :'( USA is so backwards when it comes to measuremenrs
&
amp;gt;:o
what's the advantage of having gears to look like that? The v shape.
I was sleeping, I only posted it 8 hours ago:D
As Sublime says, the self center and the gears are always in contact. This removes backlash and makes them quieter.
The teeth always have even contact (removes backlash) and they self center.
More from rhys-jones
Come on!
The large driven gear part without holes is upside down!
How can one do a circle inside a hole 5mm in the air???
The non-holed part if printed upside-down and with 0.3 infill is half the print time btw...