The whole point of the mold positive is to create the molds and associated cores which will be used to actually cast the part. Without further ado, here they are!



Making the mold positive

Before we can make the mold, we need to create the mold positive. This is basically a case half, except we make it out of plastic. It’s not just any case half though – it’s a reproduction of our raw casting, which means that it is dimensionally different than an actual case, and it lacks some of the holes and features that a finished case would have, because those will be machined on the case post-mold.

The process of machining the 1:1 scale case half in plastic takes a CNC machine about 30 hours to do – for one case half. Here are some progress pictures……starting to look like a case!

You scanned a case. So what?

Although scanning the case was a monumental and expensive effort, in and of itself, a Solidworks drawing of a case is pretty much useless for building the tooling needed to actually build a case.

But it’s a start.

This is where the toolmaker comes in. In order to cast new cases, you need to build tooling. Mainly, this is where the bulk of the expense lies in this little project.

Also, and super importantly, the case doesn’t pop out of the mold looking like one that’s in your car. Here are the differences:

  • The raw casting needs to have machining meat on the mating halves, the mains, and just about every surface that will be machined in any way, shape or form. That means that our casting will be thicker in many places than the actual finished case, since it will be machined down later.
  • We need to add draft to our drawing so that the case can be pulled from the mold properly.
  • Our case is sand cast; the original Porsche® case was die cast. Die casting is a little different than sand casting, so our mold is markedly different from a die cast mold.

In short, the Solidworks drawing needs to be worked over by a team of tooling and pattern makers into something that can be used to make a mold. Which is very, very expensive!