Speed for cutting Woodruff key in 303 Stainless

Can anyone help me out, I primarily work in aluminum (forgiveing) But I need to cut a .125 slot in a 5/16" 303 Stainless rod. I have ordered a 1 1/4" Woodruff key cutter to do the job but being a greenhorn have no clue what spindle speed to use. Can anyone out there help me, the part is a door latch for a homebuilt aircraft (see

Doug

You should be safe running your cutter @ 250 RPM. You should be able to machine 303 @ 125 SFPM safely, but keep it somewhat slower to be on the safe side so you don't smoke the cutter. What's important is that you have your rod held as short as possible to minimize how much sticks out so it's not supported, and that you make the cut such that the teeth push away from the rod as they cut. If you attempt to climb mill it, or if you permit the cutter to get on the side of the rod such that the teeth can pull the part in as it cuts, it will go pear shaped on you in a hurry. Lubricate the cut well with sulfur based cutting oil or equivalent, applied with an acid brush. Don't try to cut it dry.

Harold

That's pretty slow! Only 26/39 SFPM. 304 or 316 could be machined at a higher rate (75 FPM) , and neither of them are free machining. Even my recommended speed (250 RPM) is safe, well under the maximum recommended for

Yes, it will cut at the lower speed, but it will cut much better at a higher rate. One of the benefits is usually a smoother operation, with less banging as each tooth cuts and releases.

Harold

I figured it at 121 RPM, which I think is appropriate for the HS machinist. If this isn't production where tools and grinding might be of secondary importance, not toasting the tool is probably most important... for economy.

Carpenter lists their 303 Project 70 at 100-140 SFPM, which I think is