View Full Version : Copper machining

10-27-2003, 04:54 PM
I need to make a hole about 3/4 in dia. in a chunk of copper. Can anyone tell me the proper lubricant to use, and/or the type of drill bit to use, will a speed bit do it without grabbing? I know a regular bit will dig in, and as I can't chuck this irregular shaped piece, it looks like a drill press job. I can clamp it in a vice, but my first attempt at drilling it met with disaster for the drill. This is worse than soft aluminum. I also need to tap a hole for a mounting stud, but I don't want to ruin a tap, or the piece. What's the best way to go about this?

10-27-2003, 06:23 PM
Drill with amorphous diamond coated bits (Dialub) or hard chromed bits. $$$$

10-27-2003, 07:08 PM
Try this: take a small stone and stone the relief off the drill flutes, i.e. hold the stone parallel to the axis of the drill and stone the cutting edges a bit, so the front faces are straight up and down.

Allegedly, the lubricant of choice for copper is...milk. No kidding.

10-27-2003, 08:07 PM
Yep. Got Milk? I had a job of making several thousand contacts for industrial spot welders. Do not use a spade bit. If this is dead soft copper the hole will want to close behind it a little.
SGW is right 0 rake in the drill bit.
I'd do it in the mill so that you can control your downfeed. You can run the drill pretty fast, but go slow on the feed.
Clean up thoroughly. If you've ever smelled spoilt milk you'll know why.

10-27-2003, 08:46 PM
I like the idea of controlled feed via the mill. Also, follow the idea of the relieved rake angle on the drill bit. I do this with copper, and it works well. I use normal coolant for the copper. Use a spray bottle with coolant in it, spray it on. Seems to run well. Also, run a "chipbreak" type of drilling action. Peck it in. be careful not to lift up on the peck too fast though, or you leave little "drill hooks" (the stopping point of the drill bit, leaves a ridge, or a bit of a hooked burr) to catch and spin the drill on the next pass / peck.

never really had a hard time with copper, never figured out why, and now that I have said this. probably will next time.

10-28-2003, 12:57 AM
Milk. For that control flow container they talk about just sling ol' Bessie up over your shoulder grab a teat and shoot to kill.
OK, so maybe a smaller container WOULD be a better choice, but Milk, no foolin'.

10-28-2003, 03:57 AM
Well, who'd a thunk it, milk. Couldn't get any cooperation from old betsy, so I'll have to get some milk from the store. I did cobble up a way of chucking it in the lathe, and drilled a pilot hole using something similar to wd40, worked ok. Now to bore it to size.

[This message has been edited by darryl (edited 10-28-2003).]

10-28-2003, 03:04 PM
Is that 2% Milk or regular?? LOL

10-28-2003, 05:58 PM
That must be 2% for occasional use, and full strength for production use.

10-28-2003, 06:31 PM
Fat free for thin stock?