From: admin (firstname.lastname@example.org)
Date: Thu Jan 09 2003 - 18:20:54 EET
Thanks for this post.
We run a machine in a small animation/digital sculpture lab at our school, NYIT in New York. I agree the costs are eating us alive too.
I've tried a few things. I've run plaster through it to no avail. I've strained and reused binder, which can give a rough part. I've wanted to try something with flour and plaster mixed. I've tasted the powder and it seems to have a floury taste. Who knows?
I also find post processing to be problematic. I've experimented the most in this area. Gorilla Glue, unthinned, can be applied like the cyanacrolate. You can also thin it with Xylene (but its "whew" obnoxious-- poisinous-- use all the precautions). Another drawback is that in the corn starch material the glue will rip the surface. It contracts while drying, leaving cracks in the part. They are sometimes large
Pure shellac works nicely but I don't use it. Firstly it doesn't have a super strong bond. Shellac dissolves in denatured alcohol and so isn't as obnoxious, though its still smelly. The main problem is that alcohol seems to lessen the bond between materials while it's hardening. Parts have to be supported somehow. I got this tip from a kindly person on this list!!
I've used all of the above solutions with a pressure pot (paint pot) at about 30lbs psi which works nicely because it drives the material into the part. Its all a lot of work no matter how you slice it. I dream of finding a simple, cheap, non toxic solution.
After post processing and cost, my biggest problem with the parts are how much they break while handling. I guess my sculptures could be reengineered to maximize the qualities of the machine. But that was the interest in RP to begin with-- parts without compromise to the process they are being made with. Cantilevers are always problematic as are tiny features like toes. (I've often said... "If I have to glue another g@# D#%^* toe on I'm gonna scream.")
Anyway, I'd love to keep informed of anything that you do. And I'll do the same.
----- Original Message -----
To: Rapid Prototyping Electronic Mailing List
Sent: Wednesday, January 08, 2003 5:11 PM
Subject: Re: Zcorp users...
Hi rapid prototypers,
Have any of you Zcorp machine users, come up with a substitute for Zcorp's plaster-based powder. At $500 for 15 pounds of the stuff it is eating us alive. Our students here at UCLA Architecture are using our new/used Z402, 24 hours a day.
Our UCLA Bio Medical Department also has a machine and they are using ordinary granulated sugar with great success but we would prefer to use plaster of Paris or something, here in architecture, if we can.
Here is the scoop on the sugar if you are interested. Our biomed students are using ordinary granulated sugar (the large bags) from Costco. Powdered sugar is too fine and doesn't work. The granulated is a little coarse so they run it in an ordinary blender and shake it through a sieve. They run plain water or ink on it. The print head in a Zcorp Z402 is an ordinary Cannon unit that takes standard cartridges from Office Depot. ($35 instead of Zcorp's $65) Sometimes they simply run the black ink that comes in the cartridge. It makes great looking black parts. Their parts look and feel the same as our plaster parts but their machine must be kept immaculate or it will gum up.
Their use for these parts is really incredible. When a person has lost a part of a bone or cartilage they digitize the cavity and model a piece to fit. They then take T cells from the patient's marrow, etc., and incubate them on the sugar part. The sugar part has a porous lattice, so the cells permeate the entire thing. After incubation, they wash out the sugar and have a beautiful bone piece to implant.
Kirk Alcond, UCLA Architecture, Shop Supervisor,
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