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Pressed in cups, I guess, were case hardened? They’ll be softer underneath.
How deep does the case hardening go?
I think it’s pretty shallow, I can see why pressed in cups need to remain ductile.Would it not be possible to re-case harden after grinding the races?
I’ve got a Magistroni fork crown race that could do with a bit of love.
🙂
absurdbird-
This was the company that did a couple of crown races for me https://www.universalgrinding.co.uk
I had to continually chase for months both times, although to be fair the second time there was some sort of global health pandemic going on. Like I said, I think it was just a small annoying job amongst other stuff. They did a really good job though. As far as I know ‘hard chroming’ (which they offer) would give you a good bearing surface after grinding. -
How deep does the case hardening go?
I think it’s pretty shallow, I can see why pressed in cups need to remain ductile.Would it not be possible to re-case harden after grinding the races?
Uhhhh, you're crossing over my knowledge bands here now!
I've case hardened and ground thrust bearing races before. You case harden, then grind the surface. I don't know how deep the case hardening goes, but the divots that the ball bearings make are definitely deeper than the case hardening. So, to get a new, perfect surface, you'd need to dress the surface back to remove the divots, then case harden or nitride or whatever was done, then grind again. I don't know how curved surfaces are ground, there's a chance it might be done with something hard like silicon nitride balls and a grinding paste.
Like I said before though, I'd wager you could do similar if you were to pack the races with silicon nitride balls and a fine valve grinding paste, then spin the assembly with a drill. If you just took the worst off, you'd probably turn a rough headset into a perfectly useable one. even regular ball bearings are probably hard enough to do this.
veloham
Jonny69
Depends on the headset. The frames I’ve had with integrated headset cups and drop-in races (e.g. roadsters, anything with a headclip), the races have been machined from high carbon steel. They’ll be the same hardness all the way through. Pressed in cups, I guess, were case hardened? They’ll be softer underneath.
I would intend to literally only dress the surface. I’m pretty sure you could make the headset 80% better with 20% work; at the least make an unusable headset usable again, but not perfect.