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[RobH2]

You guys are posting some great stuff here. This thread is working out exactly as I hoped it would. Keep it coming.

I'm jealous of you guys with the new rail version of the printer. I need to go ahead and upgrade mine. I'm getting beautiful prints with my rod version these days but I do love the look of the new one. Keep modding....

[flywheeld]

First post on here...
I've built a "plug-and-play" belt-driven 3mm dual extruder that uses pretty standard Greg's parts, adapts onto the i3v X carriage, and plugs directly into the RAMPS 1.4 without any extra mods. Been printing at normal speeds for the makerfarm i3v without an issue. Figured out all of the necessary changes to the firmware thanks to this forum and others. Here's a video from early on in the testing:



Nozzle offset is ~33mm, so not much taken away from the build envelope. The dual hexagons run great with the right slic3r settings to cut down on the ooze (not the ooze prevention settings, but the retraction settings when tool is disabled).

All in all, I'm really happy with having dual extrusion on the 8" i3v that can use 3mm filament and that has plenty of torque on the hobbed bolts to keep the speed up. More pics to come soon.
Photo Oct 04, 8 01 04 PM.jpgPhoto Sep 30, 6 51 12 PM.jpgPhoto Oct 04, 8 03 36 PM.jpg

[clough42]

I've been wrestling with a design like this for a while, and had concluded that the only realistic way to make it work would be to get the motors up above the filament clamps. Good job.

Are those NEMA 17 motors? I think this design will work with NEMA 14 motors in the 20oz.in. range.

[TopJimmyCooks]

clough42 - I printed your belt drive extruder and got a nema 14 motor from pololu. It will probably be a week or two of resolving a few other issues I'm working on, but I will install it and see how the nema 14 does and if it works well. Using 3mm filament/j head/0.50 nozzle. The pololu part is #1207 Stepper Motor: Bipolar, 200 Steps/Rev, 35×26mm, 7.4V, 0.28 A/Phase = 12.95. I deliberately got a 26mm to see if the smaller size could possibly cut it.

Flywheeld: If it works well it could be a good one to use with this dual extruder. 26 mm x35 x35 case size.

[clough42]

I'll be curious to see how it works. My gut says that the larger Nema14 is getting pretty close to the limit, but it's definitely worth a try.

[RobH2]

flywheeld, this is really exciting. I've been wanting to go dual-head for awhile. I have the previous version of the Makerfarm but I'm sure it can be adapted too. I look forward to more pics and if you get to the point you want to share some actual parts and design specifics, I'd be happy to have a look and do some testing myself. Nice job.

[flywheeld]

I elected to go with NEMA 17s for the torque and for the commonality with existing Wade's/Greg's. Originally I had designed it with 14s, but after further research I was afraid of reliability and speed issues due to the lower torque. The size/weight vs speed doesn't seem to be an issue for the x-axis motor (probably thanks in part to the low friction v-slot extrusions on the i3v) and I haven't had a single problem in about 100+hrs of printing with it. I'll put files out soon and will probably try to sell the hardware by itself in addition to the whole extruder.

More info on the design, etc here: http://www.flywheeldesigns.com/blogs...-i3-prusa-easy

[AbuMaia]

Thanks to Clough42's advice, I was able to modify one of his endstop mounts to hold a 40mm fan for the Y axis stepper. http://www.thingiverse.com/thing:498414

[AbuMaia]

For a dual-extruder setup on an i3v, I keep thinking the easiest route would be to print out a second set of X-carriage parts, and get 3 slightly longer bolts to go through the wheels to attach a second carriage to the back of the original carriage. This would sandwich the extrusion between the carriages, which would share the wheels. You'd lose 0 X distance, but maybe too much Y distance. Though any lost Y distance could be compensated for by using longer Y axis extrusions and belt.

[clough42]

For a dual-extruder setup on an i3v, I keep thinking the easiest route would be to print out a second set of X-carriage parts, and get 3 slightly longer bolts to go through the wheels to attach a second carriage to the back of the original carriage. This would sandwich the extrusion between the carriages, which would share the wheels. You'd lose 0 X distance, but maybe too much Y distance. Though any lost Y distance could be compensated for by using longer Y axis extrusions and belt.

Actually, another extruder behind the rails would strike the frame on both sides.

I'm still thinking. Y separation is interesting to me as well, but it would have to be in front, which adds more torque to the load on the wheels.

I'm also thinking about ways to get the nozzles closer together. Like the heat blocks 2mm apart. Tricky, but I think possible by staggering the hobbed bolts in the right way.