I've got a little HF Vise and to be honest except for spring tension
engraving I've found it to be pretty much useless. A couple weeks ago I
found a use for it on my CNC mill. I bolted it down with a piece of .125
aluminum sheet under one edge and milled the flange of the vise nice and
straight. Then I set it down and squared the table to that edge and milled
the top of the flange flat. This forms a beautiful sharp 85 degree angle
approximately about .250 above the surface of the table. Now when I want to
make a mold I just butt the stock plate up against that and use a piece of
aluminum angle with a piece of sheet under it as a leverage pressure clamp
on the other edge of the piece of plate. Wow. The two working together
seem to actually draw the work piece down against the surface of the table.
It used to be when I surfaced a piece of stock I might have to take off .006
to as much as .009 before I could start working. I was always wondering
that the mill stock was that irregular. The last half dozen pieces have
taken less than .005 consistently and many could have gotten by with .003 or
less to make them flat. I guess the stock rolling out of the mill was
better than I thought.

So, to be quite frank, not only is an HF mill drill vise good for a door
stop, with a few minor modifications it makes an exemplary one. LOL.