scale drawing

Robert E Morey · Post by **Robert E Morey** » Tue Sep 23, 2008 3:26 am

David,
Glad I could be of help! I think your idea of machining the tubes is the correct approach. The pivot points (steering knuckles) will be under a lot of stress. Machined alum or brass would be better for tubular parts.

I use teflon cores in any though holes etc. It works great, the metal will not stick to it, and usually no re-drilling is required.

I haven't tried recyling RTV into a new mold - but that sounds like a great idea!

Anything to displace mold rubber would be a good savings.

Thanks I will consider that on my next mold.
Bob

Tim Bowman · Post by **Tim Bowman** » Tue Sep 23, 2008 4:44 am

Hi David and Bob

David, I have cut up older molds to use as filler on new ones many times. My only suggestion is to use pieces from molds that are not too old. Year or more. It will work but pieces of newer material just seemed to be better. You can also grind up older molds to reduce the size of the filler pieces. Old meat grinder works great.

I can't wait to see those axle housings with oil in them!

Bob, where do you find the teflon cores you use. Is it machinable or do you buy off the shelf diameters?

Thanks in advance.

Tim

Robert E Morey · Post by **Robert E Morey** » Wed Sep 24, 2008 5:01 am

Tim,
Great advice on grinding the RTV. Now where did I put that sausage grinder....

Do you have to worry about mold release or anything on the old mold?

I buy the Teflon (PTFE) rod in stock sizes from McMaster Carr in LA(keyword Teflon, PTFE) and machine it to the size and shape I need for the cores. Its easy to machine, resists fairly high temperatures (500F), can be used over and over, and best of all white metal will not adhere to it. Its also faily inexpensive. You could probably buy it and have it same day since MM-C is in LA.
http://www.mcmaster.com

Bob