On 17 Feb 2010 17:40:36 GMT, steamer wrote:

--Aha! Looks like RCM is da place after all. Well I'm trying to make
a die to make these: http://www.nmpproducts.com/nmp02.htm

Cool.

--I dreamed this up more than a decade ago and I've given up on
trying to get a die made that costs less than any potential worldwide sales
of the widget in question. Sooo I've managed to carve out the fin part of
the cavity with a Bridgeport and my little Sherline rotary table (total
depth of fins not right due to short endmill; longer ones back ordered). But
making the 3 inserts (and the plate that will hold them accurately) is
getting a bit tricky. Will try to post some photos to my blog in a day or
two.

Steel or aluminum? You planning on unscrewing a threaded bit to get it
out?

--I'm thinking of pouring in an epoxy of some kind as I really don't
want to injection mold them until I get the geometry of the die just right.
Gotta figure out what's available that has the correct durometer; something
like nylon would be ideal.

Have you looked at cast urethane (you probably have a vacuum pump for
degassing)?

For a test run you could also consider doing rapid protyping, but it
will be a few hundred dollars cost most likely.

--I've got one of those 1/3 oz injection molding machines that
a now-gone supplier of same for trade schools sold many moons ago but it
needs to be thoroughly gone thru as it's been sitting idle under the
workbench forever; that's another can of worms I'll need to open eventually..

Is 1/3-oz enough?