That's a pretty big hole to try and drill by hand because you are
feeling the torque caused by those tips as they cut the aluminum. Unless
you have 19" biceps and press 500 pounds, I doubt the result will be
very pretty. As for "stoning" the bit, IMO that sounds like advice from
someone who spends a lot of time stoned. Without some experience,
anything you do to the modify bit is likely to make it worse not better.

Forget the air drill. Take the wheels off and drill them on a drill
press with plenty of lube and some clamps.


MinorMania wrote:

Hi All

I need to enlarge the mounting holes in a set of cast aluminium wheels from
5/8 to 17.5mm. I have a new reduced shank drill that I am using in an air
drill (hand held) as I don't want to demount the tyres.

I'm finding the drill is grabbing quite badly in the soft aluminium. I found
in a search that you can 'stone' the drill to stop this happening, or at
least make it better. I'm curious about which part of the drill should get
this treatment though. The cutting lips, or ???

Thanks, Trev.