Wednesday, February 2, 2011

Moxon Double Screw - Take 2

So the story continues. It's a little bit discouraging that it's taking me so long to get a functional double-screw vise constructed. Two flat boards, four holes, two tapped, a couple threaded rods and a pair of handles. It should be an afternoon project but it hasn't been.

My octagonal handles had a couple issues. The hole wasn't bored parallel to the handle, so the threaded rod comes out a bit skewed. I was willing to live with the minor ergonomic inconvenience, but after a few trials on the vise, the handles also turned out to be too large. At that point I decided to rework the handles, of course this also meant I could address the lack of parallelism.

Aside from the handles, another issue arose. The screw wouldn't thread all the way through the board, again. After some inspection and fiddling with the screws, I determined the threaded hole wasn't threaded completely perpendicular to the face of the vise. This results in the rod entering at a slight skew, which causes it to bind as it works it's way through the board. The effort required to get everything parallel and perpendicular is not insignificant. My solution here was to run the tap through from the opposite face. The result is a slightly sloppy fit between the screw and the hole, but in the end it shouldn't affect the efficacy of the clamp.

So I've reset a bit, tweaked things a bit and have my pieces. I've run out of time tonight, so boring out the handles and assembly will have to wait until tomorrow.

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