Screwdriver
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- 10,552
The worst aspect of this poor old thing (1945) is that the rotation was locked solid. I knew what it was but thought I'd better check the concentricity of the rotating jaw.
Looked ok, polished lightly having gone to the trouble of getting it mounted. This is the problem:
The rotating body has at some stage been turned down, the clamp has to move further causing the bolt to tip as the top of the clamp bends too far.
Wedged some aluminium shims in the join, clamped it down and bored the inside as round as I dare remembering a few thou too much and the part is a doorstop. It came out ok, the boring bar would just about make a cut as it gradually ramps into the ovality in the bore. Probably 75% to 85% round after taking 15 - 20 thou.
The clamping bolt was also horribly bent.
Not for long!
After that, I fired up Mr. Blobby my trusty MIG and built up the head. I figure if it went horribly wrong, I'd just make another one.
But it went well and the part is saved.
More...
Looked ok, polished lightly having gone to the trouble of getting it mounted. This is the problem:
The rotating body has at some stage been turned down, the clamp has to move further causing the bolt to tip as the top of the clamp bends too far.
Wedged some aluminium shims in the join, clamped it down and bored the inside as round as I dare remembering a few thou too much and the part is a doorstop. It came out ok, the boring bar would just about make a cut as it gradually ramps into the ovality in the bore. Probably 75% to 85% round after taking 15 - 20 thou.
The clamping bolt was also horribly bent.
Not for long!
After that, I fired up Mr. Blobby my trusty MIG and built up the head. I figure if it went horribly wrong, I'd just make another one.
But it went well and the part is saved.
More...