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I am building a workbench with a leg vise using a traditional parallel guide/pin board. The vise screw is an off-the-shelf 18" metal vise screw, vise screwthe legs are southern yellow pine and the vise chop is also southern yellow pine, 2" thick.

There is one thing I am not 100% clear on. I know that a leg vise chop doesn't remain parallel to the leg in use, to ensure the top contacts first and also because the pin board can only support so many discrete pin positions. But I have not seen many descriptions about where in the system the pivot occurs and planning for it.

Since the screw and the nut have some play, about 1-1.5°, and the handle/garter end of the screw does not, I am assuming that all that pivoting comes from the angle of the vise screw inside the nut. The nut is in theory rigid to the leg, and the screw is in theory rigid with respect to the vise chop. To that end I am planning on drilling a tight hole for the vise screw on the chop side, and a slightly larger hole in the leg. The amount to over-size the leg hole I can calculate using trigonometry given the leg thickness and the expected pivot angle. (I suppose ideally it would be a tapered/conical hole but I'm not sure if I will go that far.)

However, I have never really seen anyone describe using a larger hole in the leg than the chop, and I have also heard people say a leg vise chop bends in use, or that they install bushings somewhere in the system. Or, maybe people just let the screw chew out the space it needs in the leg hole in use. Anyway, I'm worried I'm missing something.

Is my plan to drill a larger hole in the leg to allow for the screw to pivot reasonable?

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  • I may be missing something in your question, but any angle on the chop leg is set using the settings on the guide rail at the bottom. I believe the screw hole should be drilled more or less level in the leg and slightly larger than the screw to allow the screw to pass freely through the leg.
    – Ashlar
    Aug 22, 2020 at 16:24
  • @Ashlar Yeah my question is about the "slightly larger." I can either drill it so it's just barely a clearance hole (say 0.005-0.010" larger diameter than the screw) or I can drill it so there's enough room for the screw to pivot +/- 1° in the nut (which would be more like 0.100"-0.125" oversize.) Aug 22, 2020 at 16:41
  • It does not matter, the threaded rod is held horizontal by the mounting plate/nut that screws to the leg.
    – Ashlar
    Aug 24, 2020 at 0:37
  • @Ashlar Okay, so I'm lost as to how this whole mechanism is supposed to work, then. I'm going to draw some pictures and update the question. Aug 24, 2020 at 1:54
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    @ScottHilbert that sounds right, if I'm understanding. These vices are intended to not grip square, but true to the piece up to some maximum.
    – jdv
    Aug 24, 2020 at 15:23

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