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garyphansen
03-30-2005, 08:49 PM
I have about a 6" dia hole in a 1.25" thick alu. plate. I need to shave about 1/16" off in a coulpe of places. I could use a file but I have heard a wood router can be used for this. Any thoughts or cautions?

Gary P. Hansen

precisionworks
03-30-2005, 09:43 PM
Gary,

A woodworking router CAN be made to work. Here's what I've done.

1) You'll need a router that has a 1/2" collet & variable speed (or a speed control box)

2) The best end mill is solid carbide, 2 or 3 flute, high rake. Normal end mills for steel work have a 30* helix. Aluminum shears (and the chips evacuate better) with a 45* helix. Some of the brands that work well are Niagara Elite Series, Metal Removal MASTERmill, SGS Ski-Carb.

3) Set the router speed control to the lowest setting (about 10,000RPM). That yields about 1,300SFM. Most data suggests 800-2,000SFM.

4) Take light cuts. The collet in the router is the weakest link in the whole system. Woodworking router bits generally use helix angles of 0* to 10* and generate low extraction forces. The 45* helix endmill is constantly trying to pull itself out of the collet. Milling machine collets like TG & ER are designed for this, router collets aren't. Mark the shank of the cutter so you can easily tell if it's starting to pull out.

5) A shop vac or compressed air will aid chip removal.

Aluminum isn't difficult. It's just different.

------------------
Barry Milton

Mike P
03-31-2005, 11:47 AM
Be sure to wear ear plugs. It'll be LOUD!!!!

I've done some freehand routing of aluminum and I was surprised at the decent finish possible. Certainly not a precision surface, but it looked nice. I was using a 1/4", single flute (double flute?) straight cutting woodworking bit in an older light duty 1/4" router.

Mike P

[This message has been edited by Mike P (edited 03-31-2005).]

[This message has been edited by Mike P (edited 03-31-2005).]

Dave Opincarne
03-31-2005, 01:40 PM
You can do it, but you need to be aware of a couple of things. Most imprtantly is that a bit with any helix to it is going to try to pull itself out of the collet. Trust me, an end mill that's just pulled itself free and spinning at several thousand rpm's is not something you want to be in the same room with. Make sure the collet is snug and KEEP CHECKING IT as you work. Also, in order to get a good finish you need to take light cuts. A heavy cut will cause the bit to deflect into the workpiece causing it to undercut the line you're working to.