How to drill burr-free holes in round Al tubing?

I had the same problem last year while drilling a series of holes for telescoping tubing and push button locking. I ended up buying a special drill bit from McMaster carr designed specifically for this purpose and it worked like a charm. One trick was to not push through but to release pressure as the bit goes through the metal.

Do you know the type of drill you used, or could you describe what it looked like? I've looked through both the McMaster-Carr and Enco catalogs but haven't been able to find a good drill bit for this.
-Jim

I can't find the paperwork and have gone into their catalog in hopes of helping you. But can't find it. I think I had to call their technical people to get the right drill. Give them a call - McMaster Carr - 562 692 5911 or their website.

If you want to research the deburring problem in detail, request the book "Deburring and Edge Finishing Handbook" by Laroux K. Gillespie from your local library's interlibrary loan capability (or spend huge $$$ and buy it). He's very wordy and PhD-like but there's a lot of good info in there. I just did that very thing, researching vibratory tumbler media. It's supposedly the only real definitive deburring work out there.
Grant Erwin

I don't know for shure, but I'm thinking you'd have the best luck with something that didn't have a lot of twist to it... almost wonder about using an endmill (though a drill chuck won't hold onto one very well, and you'd need to either have a centercutting one or predrill undersize). Something with straight flutes and a twist-drill type pilot might be the best.

The helix angle of the drill becomes the rake angle of the cutter. Aluminum likes positive rake so a low-angle/no-angle helix would be inappropriate.
I sharpen drills which are for thin materials with brad-points. You have a small pilot point in the middle, and then the OD (margines) of the drill contact the work next. This typically results in very little burr, and you definately won't see the junk blown out the exit side of the hole. Make sure to make the clearance angle on the end of the flutes reasonably agressive. You don't want the drill to rub. Be warned that this will also cause the drill to grab if you're not careful (a drill press is ideal).
This type of geometry will generally result in a small disk being cut completely away from the stock material leaving only a small burr. Aluminum is sensitive to the cutting lips' sharpness so make sure to do it correctly. Using the correct down force is important, as Wayne specified, because the material loses strength as it becomes thinner. Pushing hard at the end of the hole will cause the aluminum to bend away from the drill, leaving a nasty burr.
You can find pics of brad-points on the internet. While you may be inclined to buy a brad-point drill, remember that they are generally used for woodworking and the steel used is unlikely to be as appropriate for metals as the steel used in high quality HSS drills.
Regards,
Robin

"Noone special" wrote in news: snipped-for-privacy@p79g2000cwp.googlegroups.com:
See if you can find a set of Black & Decker 'Bullet' drills. These are brad drills that Robin spoke of, but for metal.

Jim
If the tubing is straight ream it with a reamer that would remove the burrs and not take too much of the tubing.
Bob AZ

Robin is spot-on. We had a similar problem to yours in our shop, and in desperation, tried every aluminum cutter of supplier. The winner? A single-flute, *aluminum* router bit. It has insanely high rake, and a highly polished flute. I would fully expect that you would have close to no burrs, depending on alloy.
The router end mill is somewhat like a brad point, with one flute and no brad :) I can't speak for this company, but they carry the type I speak of:
The ones we used came from:
Good luck. Brent.

P.S.- I should mention that this is best for thin-wall tubing. If the thickness of the tubing is less than say 1/4 the diameter of the hole, a brad point might be faster for high production. Experiment.

Those Black and Decker Pirhana brad point bits are great for aluminum. I have a set and they are all I ever need. Not sure if they can be resharpened by hand

Try one of those uni-bit or step drills that can drill several different size hole, it the only way I could drill polyethylene with no burrs.

They are good for deburring the ends of small EMT, too.