Casting mold tip

watershed · Post by **watershed** » Sun Apr 06, 2003 10:36 pm

This kind of hooks with the casting failure thread.

I've been working on some long tubes, approx 4" diameter, with a 1 1/4" hole down the middle. I have had lots of probs with the core, falling over, just because of it's lack of thickness.

I seem to have it licked. I've started taking a chunk of rebar from Home Despot, and imbedding that in the core, casting the plaster around it. So far success. A couple of tips though. Make sure the rebar runs the entire length of the core, or the core tip (un reinforced) make break off. Also make the rebar go to the bottom of the plaster. I've also wired 2 pieces togeher to get the proper length. Works fine.

I don't know how thick it really needs to be, the rebar was handy. 17 guage wire(electric fence wire) worked fine to hold the rebar together, so I would guess it to work as an armature, if you needed a more complicated support.

The other thing is to let the plaster set well, no rushing, before moving the mold empty. I tend to steam my molds as soon as they are set, and that can cause issues, if the plaster isn't quite finished. I haven't noticed any damage from moving the molds with the wax in place.

Greg

Ron Coleman · Post by **Ron Coleman** » Sun Apr 06, 2003 10:53 pm

Just curious what wax you are using and how your are forming your wax model. I've been working with brown victory wax and would like to find something a little harder. I tried a nice machining wax which makes great models but the high expansion rate of the wax causes cracks in the molds before it melts.

Ron

Steph Mader · Post by **Steph Mader** » Sun Apr 06, 2003 10:58 pm

Ron, the amber microcrystalline wax is firmer and less sticky than the brown. It may not be as firm as you're after, but is easier to carve in a warm environment.

Steph

Ron Coleman · Post by **Ron Coleman** » Sun Apr 06, 2003 11:16 pm

Steph Mader wrote:Ron, the amber microcrystalline wax is firmer and less sticky than the brown. It may not be as firm as you're after, but is easier to carve in a warm environment.

Steph

Thanks Steph. I'll give it a try. The brown is just to soft and sticky and isn't any fun to work with.

Ron

watershed · Post by **watershed** » Mon Apr 07, 2003 8:17 am

I'm using a mix of reg candle wax and what's called "Container " wax. It gives me stability up to about 70degF, but is still carveable with a knife. Check a local candle p[llace. I get it from Missouri candle. They're on the web.

Greg