Craig Townsend said:
I need help solving a problem. I’m trying to drill a #52 hole in a piece of brass about 1/4" thick. I clamped the brass piece to the drill press table, and lined up the bit. As I’m drilling the bit wanders from 90 degrees vertical to a 80 to 70 degree angle. I’m using a light oil as cutting fluid, but what else am I doing wrong? My only guess is that I have too much of the drill bit shaft out of the collet, and as I cut it bends. The other question is can I plug the hole with a brass rod, and solder together. If I do that will the new drill hole wander into the previous hole? This beginner machinist needs some help! Craig
First of all, use a #1 center drill (.0468 dia. X .125 body dia.) to start the hole. Don’t depend on a prick punch mark. This is a small drill (.063), so you need to push the drill as far into the collet as feasibly possible. You are only going through 1/4 inch thick stock, so you only need slightly more than that amount showing out of the collect. Better yet, only have about an 1/8 showing to go part way. Drill it dry. No oil. You will be “peck drilling”. In other words start the #52 drill into the center drilled hole and cut maybe .020 to .030 deep and pull the drill out . Clear the chips and start the drill again. Go another .020-.030 and back off again. You will get a nice straight hole that way. Every hole I ever drill starts with a center drill. I don’t do it any other way.
As to your other question about plugging the hole: you CAN plug the hole and if you peck drill as I suggested, the drill should NOT follow the old hole. Remember this: Center drill and then choke the drill up as short as possible. Peck drill and do it DRY. You’ll be good to go. I have been a machinist/die sinker for over 50 years. You have probably seen some of my machining projects posted on LSC.