Improving Drilling Accuracy after Center Punching

[jjr2001]

Probably old hat to many but I just tried this method and I must say that it works and works well.
The holes are in a base plate that has limited room for error since I did not want to drill out the sides
of the vise that the base was to be used on. It was a casting so it was not exactly symmetrical.

I did not center drill any of the holes after I center punched them.
Instead I used a 1/2" center in my drill press chuck and lined up each hole prick with the center point.
Locked the base down to the drill press table with a toggle clamp for each prick point.
Then I changed out the center for the drill bit without center drilling. Went straight to the #21 drill bit.

All the holes were drilled and then the newly drilled base was aligned to the bottom of the vise.
The base was then used as a template and the holes were drilled into the vise cast iron frame.
Drilling was exactly where expected and none of the holes broke through the sides of the vise.
The drill bit used was a #21 which was the tap drill for the 10-32 threads that needed to be tapped.

The rest of the story is in my next project: Locking Down The Vise
http://www.homemadetools.net/forum/r...905#post105773

Cheers, JR