At 06:30 PM 5/2/04 -0600, you wrote:
>Right, Harry, I understand. But just because he hasn't heard of it doesn't
mean it couldn't be done. I know it can be done because my caster has
done it. I would call the fellow back
Vance,
You'll have to accept for the moment that I thoroughly investigated
this man's ability and willingness to do what I need done and have
determined that he CANNOT do the job I need done and is unwilling to
attempt it. When presented with a foam pattern he said he would remake the
pattern in wood, make a matching conventional core box, and sand cast it
conventionally. At that point I saw no point in continuing the
conversation. He did recommend and alloy which was neither coppery red
(which I didn't want) nor a pee-yellow (which I SURE don't want), but of
course I promptly mislaid my note where I wrote down the alloy.
>You invest it, burn it out and cast it just like any other meltable pattern.
Partly so. As you know, the basic process of investment casting
preparation creates a master and mold which is reusable and repeatable.
Unless you have enough demand to warrant a female blowmold, into which
urethane beads are expanded, lost foam does not. It's one whittled pattern
at a time, which makes it viable for live steam work only if you have a
one-off, or a number of very simple (ie quickly carved) patterns. That's a
substatial potential difference in the labor required to produce multiple
parts. If I want a backup casting, or the first pour is bad, I'll have to
whittle another pattern from scratch.
Regards,
Harry
