The ones I hate are when you lost something and don't realize it....until you put it back together and it don't work.
Last week I had a "wild hair" to disassemble my Kurt-style milling vice for cleaning and adjustment. What I didn't know, but soon found out, was that the jaw "lock-up" system uses a small 5/16" hemispherical pin to center the vice jaws and apply equal pressure to the very center of them. This part fell out, and, of course, disappeared. Since I don't have any assembly drawings or parts breakdowns I didn't know it was gone, but the vice didn't work worth beans when it was finally cleaned of half-a-pound of swarf, painted and reassembled. I tried all kinds of adjustments and combinations...nothing worked. So, I took it apart again, and carefully inspected it...nothing.
Then, just by happenstance, I was showing a friend the vice parts and telling him of my mis-adventures in mill vice repair, when I noticed a shallow depression in the back face of the movable jaw. That small piece of swarf, which I'd mistaken for an off-cut, was the reason for my vice's poor performance! We both searched for over an hour without finding it. But, I did find a couple of center punches, a scriber, and a small gear that I'd been making, a month ago. With no drawings or even a good idea of what the pin looked like, I started off with a piece of 5/16", O-1 oil hardening drill rod.
I dug out my ball turning attachment, and after an extensive cleaning and a new HSS cutter, I turned a hemisphere on the end of the rod. A little file work, and a good polishing with emery cloth brought it almost to a machined perfection. I parted it off and filed the backside of it flat. Now, how to harden it? Wait a minute...There probably isn't a hardened part in the whole vice...what am I thinking?
Re-assembly went well, and this time, I made certain the hemisphere didn't fall out. The vice works freely and the jaws lock up perfectly...and, the fresh paint-job matches my milling machine. It's amazing what you can accomplish when you don't know what you're doing.
Last edited by saltmine; 09-29-2011 at 11:22 AM.
No good deed goes unpunished.
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