Friday, December 23, 2005


Polymer needed

Something that the RepRap project could do with is a thermoset resin that will go up
to 200 - 250 C. That way we'd be able to create moulds by RepRap for
high-temperature parts and make them at room temp. But all the everyday (i.e.
cheap...) thermosets that I can find flake out around 170 C.

Does anyone have any suggestions?

Go in the other direction: Your machine should be able to build parts out of any of several waxes, which parts could then be the basis of lost wax ceramic molds, (Easy to make!) which are usable for casting anything right up to steel.
Alternatively, I recall when I was a child we had a toy that involved building things out of a fine sand suspension. You could probably use something like that to make a sand mold, but it would require a different head.
Might be very good to look into high-temperature materials anyways - it'd be good to expand the temperature range of the machine. I'm all for figuring out a ceramic deposition head, myself. Perhaps air-hardening clay slip?
NASA Did some work into printing clay slip, and ended up with a printhead that would spray not just fine clay suspensions, but fine metal suspensions onto a hotplate. They managed to print some parts that, when sintered, were ceramic at one end and metallic at the other with graduations inbetween. Heat absorbed by the workpiece continuously dries the new slip.

I was working on this when I found Adrian's RepRap project and decided it was of higher priority than my own meagre attempts.

Vik :v)
A slip deposition head could be a very useful thing in general.
Actually, would be tremendously shiny to have a fine-detail head for slip - run PMC slip through it and get jewlers interested.
Perhaps could even do some research into making similar organically-bound metal powders, and have something nice and locally-producible. Now I need to take some various baking supplies, copper filings, and water to the forge.....
And of course, the beautifully modular design of this machine makes this just another print head :)
Yes - I think that ceramic slip and clays would be a nice addition (Hans Wargers also suggested this), especially to allow investment casting. But they also introduce a number of dimension-control problems to do with shrinking-on-drying. These can be allowed for, but would not be nearly so serious with a thermoset resin.

But as jonored says: "just another print head"; Ed and I are working on an initial design with space for 4; I think perhaps we should expand this...
Are we going to get a look at your and ed's design before too long? I recall seeing a partial graphic on the blog back in May? but nothing since. I'm getting to the end of version 1 filament extruder and have been tempted to do a design for my own xyz reprap next. I'd like to be able to submerge that urge if at all possible.
Alumilite ( claims their casting resin will handle up to 220 C. I've played with it a bit. Never tested the melting point, though.
PEEK will reach 500 degrees.
that site has lots of good plastics.
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