Drilling and tapping round bar accurately

[TFrosst]

I need to drill and tap a bunch of pieces of aluminum round bar. They're going to be either 1/2" or 3/4" in diameter. Is there a way to accurately find the center of the end of the round bar and drill it accurately? Does anyone know any tips, tricks, or special tools for this?

 

[airhead]

Sounds like chucking the stock and boring in a lathe. They are pretty useful tools - wish I had one. :rolleyes

David

 

[Gigatron]

If you're drilling in to the flat end of the stock, there's some math involved http://www.makeitsolar.com/science-fair-id...rcle-center.htm. If you're drilling in to the side, there's this nifty tool http://www.ares-server.com/Ares/Ares.asp?M...roduct&ID=82281

The best way to drill is to get a center punch or large nail and make a dent at the center point. This will keep your drill bit from walking. Then, start with a small bit and make your pilot hole. Gradually increase the size of the bit until you get to the size you need. If you start out with too large of a bit, you'll do nothing but bind it up.

Hope it helps some,
Fred

 

[TK9120]

If you're tapping the end you could try drilling a hole in a thick block of wood. Insert the rod then drill from the other end. The would need to be about as long as the drill bit. That will let you drill a straight hole. If you have a drill press just use the block to make a starting point. Then drill the rest with the drill press.

If you're doing the side, you can do the same thing but drill a hole perpendicular to the first one. It should be the same size as the rod. Place the block over the rod and drill down. Just be sure to clamp everything so nothing moves.

 

[TFrosst]

I'm going to be drilling primarily into the end. Maybe two or three holes into the side. That math trick will come in handy. Anyone know if a maching shop would charge much to just drill/bore the holes in the ends? I can tap them my self and provide the stock.