One step further.. add a thin key to a slot in a bar (silver solder etc)
which is just a little narrower than the head slot.

The Cole drills are really handy tools, it would be kinda unnatural to add a
laser spotter or other high? tech accessory to them.

A set of rods with conical tips of different diameters and lengths would be
worthwhile for relocating the hole center. It would add an extra step, but
chucking a rod with a tapered/conical point will generally relocate a hole
center fairly accurately.

FWIW..
For pilot drills, a drill diameter which is close to the width of the chisel
point (across the web thickness) of the final size drill works very well.
I find using a range of sizes to get to a final hole size to be more trouble
than it's worth (and sometimes problematic in causing missed hole
locations). An exception is a uni-bit-type step drill.
I generally spot a location with an 1/8", then use that to drill a pilot
hole, followed by the final size drill.. and always an adequate amount of
cutting lubricant with each.

--
WB
..........


"Jon Anderson" wrote in message
...
Finally put my eBay sourced Cole drill to use. I'm really running up
against the limited travel vs different drill lengths, finding it much
easier to move the head back to change drills. But then, how to realign
quickly?

With a 1/8 ball end mill, I milled a shallow groove down the length of the
column, to a width very close to the slot in the head. In aligning,
I have the clamp slot centered over this groove on the head and use the
base for positioning. Then, when I need to move the head, it's simple to
realign. There's more than enough slop in the whole setup to accommodate
any minor misalignment between the head and this groove.


Jon