Tuesday, March 21, 2006


Getting the filament out of the bath...

Brett said...

The alternative, of course, is to draw the tempered fillament down through a tapered die, like drawing wire. If that die is kept cold, it will skin the fillament over, and then you just have to take care not to draw it so fast that you overrun the extruder.

We've got to have a hands-off filament maker or we will drive ourselves crazy making filament to keep the repraps fed. We've pretty much solved the problem of extruding the filament on a small scale and we know that we can quench the filament in a water bath.

Then what? Right now we have filament that looks like squiggles. We know that we can heat the quenching bath and keep the filament pliable. Now, how do we get it out of the bath and onto a takeup reel.

How about if we put something like this just under the surface of the quenching bath water. The extruding filament is just ever so slightly heavier than water, so if we have a conveyer like this that is under water at the extruder tip and comes just out of the water at the other end of the bath and if we ran it at about the rate that the filament was coming out of the extruder tip with a little experimentation we just might be able to tease the filament onto a takeup reel.

Brett's notion of a tapered die can take the form of a pair of chute walls that progressively narrow the path that the filament can take. The warm water keeps the filament pliable and the gentle force applied by the conveyer straightens it.

Rather than wasting a lot of time designing this sort of system and making it with the Stratasys machine, better to buy one from these guys.


They've got all the bits for doing this made from ABS, so I can find out if the concept works without having to face the problem of how to make something from CAPA which will soften in the quenching bath.

You could always put the takeup reel in the waterbath...

Vik :v)
Hmmm... let me think about that for a bit. :-)
Now if we combined vik's suggestion with svend's we could create a circular quenching bath and keep it at the pliable temperature (58-60 C). The bath would rotate slowly and a small water pump would gently push emerging filament in the right direction.

An inner boundary to the bath would act as the spool for the reel. The system would be self-threading.

You know guys, I think this works. Thanks! :-D
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