I installed my Veritas twin screw vise a little over a year ago, so I'm a bit
rusty on the procedure. Seems to me I followed the Veritas installation
instructions, and things went fine. Just took some measurements, and here are
the results, pretty much in order of your questions:
1. The centers of the screws are 4" below the top of my bench ( actually
measured 1 3/4 from the bottom of a 2 1/4 thick top). The big thing here is to
mount them low enough to allow the top of the square flange around the guide
screw to clear the bottom side of your top. Mine sits about 1/16th below
bottom side of the bench top.
2. I mounted mine so the screw guides are inside the end board of the bench. As
I remember, the hole isn't sized for a press fit, since the screws on the
flange actually hold the guides in place, and a little slop allows for some
minor adjustment to align the screws, should your holes be slightly off. The
skirt on that end of my bench is 2 1/2" thick, and 6 1/2" deep to match the
face of the vice and I haven't seen any sign of weakness.
3. I did taper the jaw, per Veritas instructions, and it's worked out okay,
There is quite a bit of "droop" in the moveable jaw as you open the vice more
than 6-8 inches, and the taper does help to square it up. Wasn't too big a deal
to do the taper, I just shimmed one side, then ran it through the Planer. Don't
remember the size of the shim, but it wasn't hard to calculate. On the other
hand, my Record face vise doesn't have a taper, and it works just fine. It does
have a lot less sag, however, so that might account for the difference.
4. I did put the radius on the outer jaw, primarily for the sake of my hips. My
shop is pretty crowded, and sharp corners tend to "reach out and touch" me when
I'm scurrying around working on a project. Don't know any other reason for
doing this, however.
5. The chain drive is somewhat sensitive to slack in the linkage. Veritas
provides a 1/2 link. as I remember, so my guess is much more slop than that and
you'll start getting slippage, which puts the jaws out of parallel. Eye-balling
a tape measure between the centers of the screws, it looks like mine are spaced
right at 17"
Last thing I can think of is to be sure and put the "rub bars" above the screws
on the underside of the bench. These help lessen the sag as the jaw extends,
and without them the screws will bind enough to cause the chain to jump on one
Good luck with the install. I really love the vise. It sure came in handy on my
last project ( a new entry door)