copper speed and feed

[Quickmike]

I have a friend doing some work on a prototrak bridgeport. He is cutting a hex with a .125 2 flute carbide endmill. I'm not sure what grade of copper, but he said it was pretty soft? In the machinerys handbook it recommended 180 to 200 for drilling and reaming with carbide. that would put him at 5500 to 6000 rpms but he only has about 3500 or 4000. Any other suggestions on machining it?

[ReDEyZZ]

you could run it at 8000-10000 rpm if you had it, He should have no problem machining it at 4000 rpm.It just takes twice as long. Take a reasonable depth of cut (.04-.05") and keep feedrate low .001-.002" per rev.

 

my $.02

[Hardmill]

All you can do is Max the RPM out and adjust your feed

for the required chip load.

I always stone the bottom of the drill on one flute

to purposely make it cut a little big so it dont grab.

Drill copper can sometime be a bear.

 

 

PEACE

[mold100]

10 imp is just less than .002 chip load at 3800 rpms. +1 to dulling the drill, you can also take 6 sheets of 120 emery place them scattered in a phone book and drill a few holes in it to dull the drill. Also do not step drill the hole, but reverse step start with largest dia first to prevent drill grab. (if your drill larger holes)

[Keith Graydon]

one word, coolant

[Quickmike]

Thanks guys for the quick replies. I will pass along the info so he gets started in the right direction.