Double drilling - was Tuning pin choice

[Ron Nossaman]

>One of you posted a year or more ago about how you take the edge off of 
>the second "reaming" bit to make it follow the first hole.  I was unable 
>to follow your description of which edge you touch up.  Would you mind 
>repeating and clarifying, for those of us who didn't get it the first 
>time?  Also, is the second drilling done in the same drill press setup as 
>the first?
>
>thanks much
>
>Mike Spalding RPT

Mike,
That was me, but it wasn't for pinblock drilling, it was for reaming bridge 
pin hole for the next size up without tearing up the cap. For that, I bevel 
the front cutting edge of the bit to near parallel with the length of the 
bit, so the cutting edge scrapes as it cuts, rather than grabbing, diving 
in, and chipping the edges of the hole. This is good for enlarging holes in 
cast iron too.

For pinblocks, nothing special is done to that second bit. It's off the 
rack, as it were, and into the drill. It will follow the first hole just fine.

Ron N