Friday, February 17, 2006


The next morning of filament extruder experimentation...

After realising that pumping water and pumping pellets or coarse powder polymer are apples and oranges, I cleaned out the test rig and decided to see if I could pump a coarse granular material instead. I spooned "cream of wheat" (semolina) into it while turning the screw shaft, in this case a wood auger, with pliers.

It pumped perfectly. :-)

sorry for my naievete, but what exactly is this for? is this for creating feedstock, or is this just an alternative design for the extruder printhead?
He's making a screw extruder to generate 3mm feedstock at a practical rate.

The old Gingery design did batches only, and took too long about it.

Vik :v)
LOL! It appears that Adrian is taking it over now that he's got excited about it. He'll get it done in a tenth of the time it would take me. :-D

That's what's powerful about RepRap. :-)
I love this project, it is fascinating. Question, are you trying to come up with something similar to the laboratory extruders seen here: ?

Keep up the good work, Cheers,
***I love this project, it is fascinating. Question, are you trying to come up with something similar to the laboratory extruders seen here: ?***

No, not at all. Wayne makes brilliant extruders, as best as I can see, but they're designed as lab units for plastics companies and are good for helping determining the nature of polymer forumlations' performance in production extruders. As a result of that they cost three magnitudes more than our market will bear.

Mind, I suspect that if Wayne wanted into the market they'd outsource this tabletop design to a Chinese manufacturer for the large production runs that our market will eventually produce. I suspect as well, that they have the design knowhow to design something on the scale that we're talking about. Whether their business model would let them make any money undertaking that kind of thing would be anybody's guess, however.
Forrest - don't stop just cos I'm playing too; apart from anything else my time is a bit limited at the moment.
Don't worry about me stopping for very long, Adrian. I haven't dropped work on the filament extruder project by any means. I'm mostly excited to see what insight you'll bring to the idea this weekend or so. I've never been disappointed doing that before. I remember when you took off on the encoded DC motor concept.

I've just started work on a "for money" project that has me writing a piece of software that will score short answer responses in natural language to questions posed to public school children. Sadly, that piece of work will take off working full-time on reprap for several months. :-( The upside is that I get royalties for writing the code as well as my usual consulting rate. :-D

I'm mostly right now waiting for Simon to finish adapting the control boards for the steppers to the NEMA 17's so that I can finish that piece of work. Pretty much everything else on Godzilla is good to go.

Right now I'm wondering how much torque is going to be required to drive that Mk III filament extruder. The NEMA 17's and that little gear motor that you use on the Mk II extruder all produce about 3600 gm-cm of torque (I've found several sources of that gear motor in the US now that I've had a chance to look for about US$5.60). I've been wondering if that would be enough to run the Mk III. I don't have any basis to know right now, though. :-(
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