What RPM to run at?

[neoga34]

I'm cutting a slot into A2 steel using a 7/64" end mill. The end mill is carbide, as it is the only one that had the cutting depth I need. I have a 2 flute bit and a 4 flute bit. I was wondering what RPM I should run this 7/64" end mill at for cutting into A2? And also, what should my depth of cut be on each pass I make cutting the slot? I normally use 4 flute end mills, but would the 2 flute be better for this? Thanks!

I should add that I am using a manual mill for this slot, not a cnc.

[Jaxbubba]

I would start out around 750 rpm with the 2 flute carbide cutter and make sure that you flood it with coolant. Take about .03 deep per pass. See how it is acting and adjust your feed and speed accordingly. At least you are not cutting D2. Hope this helps

[packrat]

Are you "chain drilling" a row of holes first? This is a big help in removing stock faster, leaving less material to remove with the end mill. Use a drill that leaves 0.020 - 0.030" per side for the mill.

cary

[neoga34]

Originally Posted by packrat Are you "chain drilling" a row of holes first? This is a big help in removing stock faster, leaving less material to remove with the end mill. Use a drill that leaves 0.020 - 0.030" per side for the mill. cary

That's a great idea. I've done that before, don't know why I didn't think of it. Thanks!

[neoga34]

So I did the chain drilling, and was running at 800 rpm with a .01 DOC, and just broke my second end mill. .03 seemed like a lot to take off per pass. Is there something I should change?

[M250cnc]

neoga34

HSS would be best for interrupted cuts

But to use carbide i would plunge cut and just take it at 10 to 20 thou

[neoga34]

Originally Posted by M250cnc neoga34 HSS would be best for interrupted cuts But to use carbide i would plunge cut and just take it at 10 to 20 thou

Thanks I'll try that. I would prefer HSS, but they don't make an end mill this size with enough DOC in HSS, only carbide. I'd have to mill half the slot, then flip the piece over and mill the other half. It's kind of a precision piece, so I didn't want to do that.

[M250cnc]

I would also check the speed as i see someone recommended 750

I am not familiar with the grade D2 but with 7% carbon steel it gives an rpm of 3800 at 2" IPM you may be able to go faster as i have set my max spindle speed to 3800 in the cam software.

HTH

[neoga34]

Originally Posted by neoga34 Thanks I'll try that. I would prefer HSS, but they don't make an end mill this size with enough DOC in HSS, only carbide. I'd have to mill half the slot, then flip the piece over and mill the other half. It's kind of a precision piece, so I didn't want to do that.

This worked like a champ, thanks again. Yeah the speed was a little slow, I bumped it up to 1000 rpm and that seemed to work well.

[M250cnc]

Hi, glad to have been able to help

Sent from my HTC Desire using Tapatalk