The issue I'm having is with the stability of the rear (fixed) jaw under load. As you can see in the picture, the rear jaw is keyed to the vise body, and held down from below with two pretty hefty cap screws (yes they're tight). With the standard steel jaws in place, and a typical work piece set on parallels about 1/4" below the upper jaw surfaces, the rear jaw is deflecting about .002 - .003". To me this is unacceptable. My 6" Taiwanese import vise doesn't budge at all. Zero.
So my question is: is there something wrong with this vise, or is deflection in a smaller 5" vise pretty much typical?
How much (if any) deflection do y'all see in your fixed jaw vises with work clamped near the upper jaw surface?
That flex seems a bit excessive. I suppose that it's possible that the mating surfaces are not perfectly flat and allow a bit of rocking. Or maybe the key is too tall and not allowing the surfaces to mate together. Or maybe the torque is just bending the vice frame.
I had the same problem with a 6 inch Taiwanese Kurt clone vise. I replaced the 1/2'' cap screws with 5/8'' cap screws and torqued them to about 400 ft/lb, solved the problem on that vice.
That sounds rite the mating surfaces could be out ,I only use a cast rear jaw and a ground insert type vice ,i'm a little anal about clean mating surfaces pardon the pun a small bur or swarf could change the game .
Metalworking Vise Jaw Stability
a small bur or swarf could change the game .
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