Wednesday, September 26, 2007


Smokin' The Gear

I darned well blew another extruder motor. Even though it had a nice CPU fan on it to cool it down, it still popped. I am pushing PLA here, not the standard CAPA filament, so the equipment abuse factor is fairly high.

Fortunately, Forrest has been kind enough to supply me with several motors from his collection, so I'll strap in a beefier one and see if I can get pumping the PLA again.

I've squished more CAPA over the bearings to hold them in place, and at least they don't seem to be twisting around into the filament any more. I am generating quite a bit of PLA dust though!

Vik :v)

Do you know anyone else using the same PLA? What kind of PLA is it, by the way?

Maybe your nozzle is just too thin for your polymer. If you raise the diameter of the nozzle by 1.2 (.5mm -> .6 mm), the molten plastics should come out twice (1.2^4) as fast (V/t) for the same pressure (very rough estimation based on Hagen-Poiseuille┬┤s Law), that is, you could lower the force applied on the filament by a factor of 2.

I guess you already tried to raise the extrusion temperature? If the number on the multimeter on your reprap is in deg.Celsius, I think you did ;-)!
It's PLA 4042D which I got as a sample from Convex in New Zealand. We use a fair bit of PLA here now.

The nozzle is already as large as I'd like, so not much wiggle-room there.

I've since cranked up the extrusion temperature to 175C. I think the problem is that the drive mechanism oscillates between not grabbing the filament enough and grabbing too much. I'm still experimenting.

Vik :v)
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