grinding aluminum

[wrenchdaddy]

I need to trim some aluminum tubing down on the inside of an tube. I tried an air die grinder and a rotary bit but it just wore the bit down and didn't take much material off at all. Is there something I could use on an electric grinder or some other way to bore out the inside of the tubing. I need to take off about an 8th of an inch. Thanks guys sorry this is for a boat project though, :)

[396_WAYS_TO_SPIT]

I need to trim some aluminum tubing down on the inside of an tube. I tried an air die grinder and a rotary bit but it just wore the bit down and didn't take much material off at all. Is there something I could use on an electric grinder or some other way to bore out the inside of the tubing. I need to take off about an 8th of an inch. Thanks guys sorry this is for a boat project though, :)
I use carbide bits. They will kick aluminums a$$ really fast!! Be careful though, it will eat it up fast. I also use a bar of soap to clean the bit. The bits fit in a regual die grinder.
396

[victorfb]

aluminum likes to be cut more than grinded. a rotozip (rotary cutting blade) on a dremel works pretty good, but its hard to control as it catches. sanding is the next easiest and much easier to control but is slower. start with a 80 or 100 grit drum sander or if you have some porting style drums and an air die grinder that works well too.

[steve d]

Know anybody with a lathe and a boring bar?

[396_WAYS_TO_SPIT]

Know anybody with a lathe and a boring bar?
That is the "proper" way to do it!

[victorfb]

That is the "proper" way to do it!
agreed..... :)

[shirkey4750]

Swagelok makes a special tool to trim stainless tubing, it is a manual trimmer and works well. It has two sides, one for inside and the other for trimming the outside.

[wrenchdaddy]

What do I use the carbide bits with? the die grinder I used didn;t seem to have much power. Could i use a drill? What about the grinding stones for drills, I saw them at Lowes, would that work?

[El Prosecutor]

Oops, wrong thread. I thought you guys were talking about my impeller again. :cry:

[Taylorman]

Tell us what exactly are you doing. Are you trying to take the burrs off of some aluminum tubing you cut? If so, i use a tapered stone that fits on my drill to deburr the inside of stainless tubing before i flare it. Works good.

[malcolm]

I'm curious how a piece of aluminum wore down a rotary bit. Are you sure you didn't just plug it up? You need to lube up the bit with some soap or something like 396 said.

[Moneypitt]

Aluminum is some funny stuff to machine. Very easy to cut, not so easy to grind. Cutting goes better with some sort of cutting fluid, I use Kerosene, and grinding will usually just fill the wheel up unless you have a special wheel for aluminum. Knocking the edge off a cutter will cause it to just rub the material, and once overheated the cutter is junk. Try a cutting fluid, be it kerosene or an aluminum tapping fluid, and run the cutter slow until you see how it's cutting, then add speed slowly until you get the results you want. Remember, if you're not making a chip, you're not cutting. Also, aluminum likes to be "climb" cut, meaning the cutter is rotated to "climb" along and spit chips behind the cut, not like steel that kicks chips ahead of the cut. Aluminum is soft, and doesn't "break" off, so it sorta mushes along unless the cutter is sharp. Course cutters work better for stock removal of aluminum, and finish the surface with a sanding disk.............MP

[HOSS]

Die bit with large groove (like a worm gear). Small teeth just clog on aluminum.

[Konabud]

Cartridge rolls on a die grinder (air) work pretty good. Either straight or beehive style

[909]

It sounds to me that you're trying to remove alot of material there even though its only 1/8" or so. Obviously a boring bar and lathe is ideal however you probably don't have that option available to you. It also sounds like whatever grinder you used is way too fast to properly cut aluminum. What happens is that with an improper bit and too much speed, the heat will harden the aluminum further, causing your bit to take the abuse. The key to grinding aluminum is slow speed, high torque, lubrication (use a grinders wax if you can) and an aluminum bit. These have very coarse teeth on them. Stones and steel bits will just clog up so stay away from them. If you have time you can order all the correct stuff from eastwood.com, or if not.... You can get an acceptable bit from any Walmart. They carry the Dremel line of bits. The one you need is either 9903 or 9904. They usually have them there or anywhere Dremel bits are sold. keep the bit speed down to a minimum and dont force it and you'll be fine.