. If I had to do it over again I'd probably start the bore with a 1/2" bit first because the larger bit tended to grab material and jump and stop the drill while starting the hole. I did oil the bit while drilling. Once the bore was started it was smooth sailing from there.
I went 13mm and it was just enough for the Shank of the 1/2-13 bolt to suit my risers....but damn these big battery drills sure have some power, it bit and near broke my wrist when fitting my fat risers... wasn't holding it firm enough....was for the second one!
Nice tidy looking risers
