16 Ga Steel - Which End Mill?

[noisillator]

Which type end mill would be best for cutting a hole, say 3" x 3", through 16 gauge mild steel? Also, if I cut the hole by hand, then just need to clean it up with the end mill, would I use the same type? I'll be using a mini-mill that accepts up to 3/8" shanks.

Sorry this question is so elementary, I have no experience at all cutting steel. Any advice on speeds and rates will also be appreciated!

[DareBee]

Use a hole saw. Don't mill 16 ga steel.

[noisillator]

Use a hole saw.

It's not a round hole.

Don't mill 16 ga steel.

What's the issue?

[beege]

If it were me, I'd have a friendly electrician punch out my shape with a Greenlee Punch, if he had the right size. Otherwise, I'd use a left-hand spiral, right-hand cut end mill, with a back-up piece of steel behind the sheetmetal. This places the cutting forces downward, and keeps the end mill from pulling the part up, in fact, pushing it down. Carbide. If you can find it in a stub, all the better. 4500 RPM, 8-10 IPM to start with (for a 4 flute). Don't try to hold the sheet in your hand. Secure it to the table WELL.

http://www1.mscdirect.com/CGI/NNSRIT...mber=560Pmode=

[noisillator]

Thanks beege, that's exactly what I needed.