Table vice for a Shapeoko 2 that has a 1" grid drilled into it's bed. The mounting points for this clamp is 3" center to center and made for #6-32 screws. They are meant to be used in pairs with an adjustable length of 3/4" on each jaw, which gives you over an inch total (why you have a 1" grid on the bed).
This clamp is intended to be used with either the 1" or 3" clamp (show with 3" clamp)
Companion to 3" clamp: http://www.thingiverse.com/thing:468536
and 1" clamp: http://www.thingiverse.com/thing:478459

Recommend printing at around 60% infill or higher. After you print them out, adding a strip of foam tape makes a very good grip.
While this is a beefy clamp and does its job well, it still has kind of a funky shape and the sharper edges might want to warp and peel the tape off the print bed, so I 0.45 DIA helper discs. If you have warping issues, try that *.stl instead of the standard one.