I had a need to 'move' by about 3/16" a few dozen 9/16" holes through 4-inch
structural steel channel (about 1/4" thick). I made a jig of oak that
wedged tightly in the channel using woodworking clamps and fitted it with a
couple of standard, hardened drill bushings from MSC (next day delivery).
Using a little lubricating oil, it was no problem at all to cut out those
segments using a 12-inch benchtop drill press. The holes, of course, were
left oversize but that was not a problem for the application in question.

The drill bushings protect the spindle bearings from excessive side loads,
assuming the work is rigidly clamped. Their extreme hardness minimized wear
on the drill and friction and galling that might occur with softer bushing
material.

David Merrill

"Karl Townsend" remove .NOT to reply wrote
in message nk.net...
...
disintegrated. So what is the right tool/method just to widen those
holes
on one side?

The right method is an endmill in a milling machine. Bet you ain't got
that.

Drill a 1/4" hole in a fairly thick piece of scrap stock. Clamp it to the
piece you want an offest hole in. Use the scrap stock as a drill bushing
guide to hold the drill on the new center. Feed slow this is hard on drill
bits.

Karl