Help Milling Copper Tube on CNC

[Cartierusm]

I need to make some tube miters on 4" copper tube and the tube it has to fit is 8" so using a hole saw is out, that's normally how I do it.

I set up a program to cut the 4" copper tube and have a good rigid way of mounting it in my vice. The problem is copper doesn't mill easy as it being a hollow tube it vibrates and seems to mill hard. I tried a 2 flue solid carbide bit 6" long and it shattered, obviously I tried to mill too much at once.

I'm going to use a 4" hole saw first on the mill and get rid of the bulk of the material then use do a regular cnc program.

My questions is what type of bit should I use, IPM and RPM. Originally I used the solid carbide 2 flute, 1" DOC, 10 IPM and 2500 RPM.

Thanks.

[djr76]

can we get a picture or drawing?

[Cartierusm]

I think I got it worked out.

I used a 4" hole saw to cut away most of the material leaving .03 on the tube. Then used the hole saw at two other points to remove move material. I ran it at 800 RPM and a down speed of around 3-5 IPM.

Then I used a 4 Flute TiN Coated 5/8" End Mill with my program, 2000 RPM, 5 IPM and 1/2" DOC. It was slow but worked and the bit seems to still be relatively sharp.

[djr76]

if you are cutting a hole in thin wall tubing, a smaller cutter would run better interpolating the hole out to finish size.

[Cartierusm]

Not quite sure what you mean, smaller as in smaller than the 5/8" EM I'm using?

I was using the 4" hole saw to remove the bulk of the material then using a 5/8" to finish it off with a tool path I created. Did you mean smaller than 5/8" EM? I can't really go smaller as it needs to mill down pretty far.