[ZZII 527]

Update:

I tried reassembling my 12:1 gearboxes today with the new press-fit A2 tool steel plates I cut and discovered a few issues with press fitting that I didn't think of:

1. I had to file out some to get it on at all, which is my fault because I went way under on the hole to be safe. Doing this, though, caused significant alignment problems. It was tough to get the press to go on straight and if it is even a little bit off, the gearbox will be tend to be stiff at certain positions.

2. Assembly was generally more difficult because of the extra constraint. I couldn't, for example, assemble the rest of it and slip the shaft in later.

3. Luckily this didn't happen because I over-filed a bit, but if you press it on real tight, it will be tough to get back off. I can't think of a good way to pull it back off since the plate comes so close to the bearing block.

So in conclusion, I think I'm going to file these out to be close fits, but not press fits. Loose enough that they will slip on and self-align during operation. If I cut more on the waterjet, I'll just make them 12mm x 9mm exactly.

Also, I was mistaken in my previous post: A2 tool steel will temper to C40-C65, not C20-C40. It comes already just below a C20. I will shoot for the low end of the tempering range, so as to avoid brittle failure.