After getting this new machine, we were faced with the decision of using the old fixture plate. There was nothing inherently WRONG with the old plate, but Harman and I mutually agreed to use one fixture plate for the left side of the case and one for the right, which would mean the plate would have less holes in it since it wouldn’t have to accommodate both case halves.

For those of you wondering why a fixture plate is a topic worthy of discussion, consider this: If the fixture plate is not perfectly flat, neither will anything mounted to it be flat! Therefore lots of time is spent ensuring that the foundation for literally every cut we will make is perfect.

For the non machinists out there – a human hair is about four thousands thick. We got our fixture plate flat to about half a thousandth, or about 1/8 of a human hair. Yep, it’s pretty flat.

Next, we tried Operation 1 on the casting, the very first operation which mills the oil filter console and chain box bosses. You may not realize it, but these two surfaces are the basis of flatness for the case parting line which we mill after we flip the case, so these need to be extremely flat.

The result was two extremely flat faces, but look at the surface finish. My cutters are substantially better than the ones we were using, and our mating surfaces are like mirrors, and perfectly flat.

What a joy these motors will be to build, and they will never leak with mating surfaces like this. The factory only wishes they could put out stuff like this.

At the end of the day, it’s not really fair to call this a “reproduction” case although we have no other words for it. Reproduction implies that it meets the same standards as the old one, which is not even close to accurate. My case meets the standards and casually blows them away. Outside of one off race efforts, the factory never put out a production case anything like this!

 

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