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.