If the vise's vertical and horizontal V-grooves are the same dimensions (as
they are in most vise jaw plates), then clamping same-diameter pieces in
each groove will keep the center lines of both workpieces aligned.

Drill bushings such as those suggested by DoN will keep the drill centered
on the horizontal piece's center line as long as the two stock diameters are
the same.

BTW, if the cross hole needs to be near the end of a workpiece, drilling the
hole with this method will likely work better if the hole is drilled before
cutting the length of the workpiece.
The longer length of stock held in the horizontal V-groove will be supported
by the entire width of the horizontal groove, eliminating the possibility of
the part shifting if it were only supported by about half of the V-groove
(particularly in smaller vises).
The increased gripping area should insure a smooth drilling action with no
surprises.

--
WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Michael Koblic" wrote in message
...

Can you be certain that the vertical groove always centers automatically
on the diameter of the piece held in the cross-grove (which would be
mandatory if one used the guide made as you suggested)?