Friday, September 11, 2009

 

Printing with 2mm filament

I recently obtained a few feet of 2mm white ABS filament and decided to try printing with it.

I use a pinchwheel consisting of a small brass spur gear. A ball bearing is on a lever and presses the filament against the pinch wheel due to the force of a rubber band (with multiplication from the lever). There is not much holding a 3mm filament from sliding sideways and out from between the spur gear and the bearing, but 3mm filament is stiff enough that it is not a big problem. When I tried the 2mm filament, I had to modify the level a bit to allow it to come close enough to the spur gear to press the 2mm filament against it. I also printed out a better filament guide to prevent the 2mm filament from moving sideways.



Once I had done these modifications, and had tweaked the skeinforge settings (halved the feedrate and decreased the expected extrusion width slightly), I was able to print well with the 2mm filament. Here is a paperclip (http://www.thingiverse.com/thing:655) by "unfold". While I was extruding, I heard a slight popping noise (frying?) which I do not hear with the 'natural' colored 3mm ABS filament (from Village Plastics). I suspect that I may be running the tip a bit hot for this material.

Interestingly, I got good results with a 2mm filament in a 3mm+ hole, which holds 3mm filament fairly snuggly. When I pulled out the 2mm filament from the extruder, it looked like this:I described the heater end of my extruder here recently (builder's blog of August 29, 2009). It looks to me like the 2mm filament is just pressing up against the dished end of the acorn nut and not spreading out much. I am probably deluding myself, but it looks like this is a hint at a simpler extruder.

Frank Davies

Comments:
After you pulled the filament out, was there any left in the barrel? I often get a shape like that when the solid filament separates from the melted region in the barrel, as I pull it back out.

I've been thinking along similar lines, but using a 3 mm filament, with a 3 mm PTFE thermal break, but then a 4 or 5 mm ID barrel. I think it might reduce the force needed to extrude, along the lines of Nophead's tapered melt zone.
 
Congrats on successful printing with that surplus filament! I think it's worth mentioning that this filament came from the leftovers in a cartridge meant for a Dimension FDM machine. Apparently, the professional grade machines require a cartridge swap after about 90% of the filament is spent - that remaining 10% is unusable by the machine. For those of you out there who have an adjustable pinchwheel, ask around the drafting and architecture departments at your local colleges - there might be good ABS free for the taking.
 
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