steamer wrote:

Spehro Pefhany wrote:
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?
--Aluminum. Threading occurs after molding, when two parts are
snapped together; makes the making of the mold much easier.

In that case, forget injection molding and think extrusion. You've got
something that's basically like a big T05 heatsink, so you should be
able to extrude as a complete part (no snap together) and then slice
into the appropriate lengths.

You could also just lathe and mill it with a 4th axis, taking a solid
plastic rod, bore the center hole on the lathe, then put in 4th axis on
the mill and mill the fins. A 24" rod should yield like 45 parts.