Being a mold maker (small niche market) this may sound funny, but its
something I rarely think about. Most of the stuff I make is rounded
and/or organic with a flat plane parting line. Ocassionally I'll make a
mold for a mold and the draft angle of the master mold is just
exaggerated. The cast mold just falls out of the master mold, cavity
details not withstanding.
I watched the series The Tool & Die Guy started on YouTube about mold
making, but he was mostly working with plastic injection molds with
ejector pins. He talked about draft angles of around 1 degree. Usually
done in setup rather than with a tapered mill.
I just started (in 5 or 6 weeks I'll cut it) a job to make a "blank"
master mold for somebody. They plan to use the master to mold their own
molds when they use them so they have to come out and go back in pretty
easily. Its really just a box. He had not even considered draft angle
so I asked him... we agreed that it needed some. Do to usage he asked
that I use the least draft angle I thought was practical. The easiest
way to do it is to rough it out of a solid piece of stock and finish
with a tapered mill. Only one setup then. When I was looking at end
mill options from MSC 3 degrees seemed to be the most common tapered end
Is 3 degrees common for some particular reason? Not necessarily just
mold draft angle, but for any reason.
When I print or machine master molds I usually go with 5 degrees. I use
the resulting cast molds (usually silicone) with a backer plate and a
2 years ago