Which is your favorite extruder ?
I’ll start building a Prusel I3 soon and trying to decide on an extruder.
Anyone has a double extruder running ?
j-head mark 5vb or whatever the latest j-head is
J-head hot end, and for cold end mine sucks but the recommendation i got in IRC yesterday was gregfrost’s extruder body with an http://archol.hu hobbed bar and whatever NEMA17.
j-head is a hot end, not an entire extruder. I can’t offer a good recommendation.
It depends on what filament you’re using. If you’re using 1.75 - an arcol direct drive gear + the extruder on thingiverse for the Prusa i3, paired with the recommended push-fit adapters is really nice.
If you’re using 3mm, I’ve always gone with the wades. If you’re going to go dual/tri extruder - you’ll want to use a bowden tube setup to minimize weight on the X axis and be able to bring the nozzles closer together.
If, like other people are thinking, you’re actually referring to the hot end, I also recommend the J-head hot end.
I personally like the j-head hot end available from http://hotends.com. It’s a solid hotend and a lot of people use it. It’s actually what I recommended to @lynnroth and it’s the end I purchased as well. Hotends.com posts inventory every Friday around noon eastern standard time (or thereabouts).
For the extruder body, people really seem to differ on what they want. I’ve printed both the single and dual extruder bodies (which use a PG35L motor)(s)), the Greg’s/Wade’s body+mount, or a 1.75mm bowden setup for the i3. Prusa supposedly has a new NEMA17 geared extruder he’s now using. However he has yet to post the scads/stls and I’ve asked for them 2-3 times now. 
I will say the Greg’s/Wade’s extruder takes a LOT of plastic. I print all of my i3 kits with 3 shells and 35% infill with the exception of the extruder parts, which get 3 shells and 50-70% infill. When printed the full Greg’s/Wade’s extruder (body, large gear, small gear, idler, and mounting platform) use ~130 grams of ABS. The part kits I sell typically weigh around 180-200 grams before the extruder is added so you can see there is a LOT of plastic in the extruder.
Everyone has their own preference. Lynn went with the Greg’s/Wade’s. I’m personally going with a modified Airtripper bowden setup for 3mm filament on my i3 (untested) as I thought I’d give a bowden setup a shot. I personally went this way as I didn’t want to move almost 1/2-lb extruder around on the x-carriage for fear of backlash at higher speeds.
@Shane_Graber is there a good geared extruder design out there for 3mm filament that uses little plastic?
Prusa’s got a really nice one on his flickr photostream: http://www.flickr.com/photos/prusajr/8465949175/in/photostream It appears to be a derivative of an older Wade’s extruder: http://reprap.org/wiki/Wade’s_Geared_Extruder I personally like it as it uses a NEMA17 motor. I just hope Josef releases the source soon.
LOL I’m actually trying a modified version of it - using an Airtripper for the motor and your jhead mount for the x-carriage. 
I didn’t have a small 623 bearing for the idler otherwise I would. The only reason I went with the Airtripper was because it used 608zz bearings, which I have 50 of. 
@Shane_Graber a fair call! Lol I hate the way spare hardware just seems to build up when modding, though never seem to have what you need!
You know…I have a couple r4zz bearings lying around. Those are really close to the 624zz size. Can the idler be modded to fit that?
r4zz:
id = 0.25 = 6.35
od = 0.625 = 15.875
w = 0.196 = 4.98
Shane, can you link to your design ?
Should I use it in my new Prusel I3 ?
I haven’t released the modded Airtripper yet. At best I have the extruder body finally modded for 3mm filament. I still have to fix the idler and then figure out how to mount the thing.
@Shane_Graber yes that should work for the idler, the bearing would be just clear of the fixings. Printing wise you won’t get solid holes for the fixings but that wouldn’t be a problem, just cosmetic!
@Shane_Graber will be interesting to see how you get on with 3mm with a direct drive extruder as when I tried I had to run the stepper at more than recommended and even then it struggled printing at anything higher than 30mm per sec! Must admit I much more prefer 1.75mm now that I’ve made the move!
FWIW I’ve run my Cupcake on 3mm filament using a direct drive extruder for over a year now. That said, it’s now bowden, so it’ll be interesting! I’ll mod the idler tonight and see what I can come up with.
@Shane_Graber if you get stuck (can’t imagine you will though) just give me a shout and I’ll mod the idler for you at weekend. Will be interesting to see if the distance to the nozzle will cause the problems I had! Though you won’t convert me back lol I like the way 1.75mm is so flexible, don’t need as high a temp on the nozzle and less work for steppers.
Ok I think I have a handle on it (I looked over the scad file). I’ll have to mod both the idler and the extruder body since the r4zz is 2mm larger in diameter.