How to cut say 3" holes in 1/2 aluminum plate???

[wrechin2]

What is a way to cut multiple diameters of holes in plate aluminum?? I will finish them with boring bar. Thanks to all the reply.
james

[307startup]

There are multiple ways to cut those holes, just depends on how exact they need to be, or what equipment you have.

You could use hole saws mounted on an arbor and chucked up in your milling spindle using an appropriate collet, if you have a manual mill and then finish to size using your boring head.

You could use interpolated circular milling to cut the holes to size using a cnc mill and finish to size using your boring head.

You could cut them out using a plasma, laser or waterjet.

It all depends on your equipment at hand, really.

[wrechin2]

I have a manual bridgeport and need to rough cut 75, 80, and 90MM holes. Would like to get as close as possible and finish with boring head. Is there some kind of inexpensive adjustable hole cutter? Thanks.
James

[307startup]

Well you could use a fly cutter and a special hand-ground HSS tool bit for trepanning the holes. That's about as inexpensive "adjustable" hole-cutter as I've ever seen.

Either that or try Miracle-Grow on smaller drill bits

[307startup]

Really, I would consider the hole-saws on an arbor. It's pretty impressive what they are capable of. You just have to figure out the proper feeds and speeds and you're good to go. I have used them on a 4th axis lathe with live tools for some of the products we were manufacturing and they work amazingly well for what they are.

[wrechin2]

The thing is, I would have to buy multiple hole saws or spend alot of time boring due to the differnce in size. Where can I see a pic of the trepanner? Where can I get one cheap? Thanks for your help.
James

[Arquibaldo]

I agree - hole-saws, definitely.

You can buy then up to 100mm in diameter
(see http://www.starrettonline.com/produt...D=61&prdID=682 for instance)
They can punch a hole thru a 1" steel plate - alu should be easy.
The arbor is hexagonal, so you can grab it very securely with a standard "jacobs" type
chuck

[wrechin2]

Well,
Guess a hole saw is it. Thanks guys!!!

[jschmitt]

Be sure to drill clearance holes around the inside to clear out the chips

[wrechin2]

Thanks!!

[USMCPOP]

Something like this might work for you:

http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=57136082

[wrechin2]

Thanks!! That helps. I am ordering some1-2-3 and 2-4-6 blocks there on Monday. They have a store 1 mile from work. Can't beat the free shipping especially on things that heavy!!!