Going fast on mild steel tubing

[BT Fabrication]

Yeah, I cut a few pieces today. The machine was singing. I played with RPMs to try to mitigate but there really doesn't seem to be a simple formula to make this happen without lots of chatter/vibration.

I have no experience with CNC plasma cutting. I did some looking around and learned of guys mounting an extension arm out the front/side of their VMC to plasma-cut outside the machine. Sounds wicked enough that I could see myself trying that one day (not for this).

What kind of tolerances can a real CNC plasma cutter hold? +/- 0.010" is probably fine for this job, maybe more.

plasma on most leave a 0.030" kerf. high def gets it to about 0.008"

 

[Rick Finsta]

I'd make an aluminum or plastic mandrel that the part slips over and then just get at them.

 

[Overland]

This is the sort of job we'd give to the apprentice back in the day. Point him to a "No5"
flypress and let him figure out a simple tool.
This is probably how they'll do it in China for low $$$.
Flypress shows my age. Younger guys can google it.....

Bob

 

[martin_05]

Closing the loop on this for the benefit of anyone facing a similar challenge.

After many tests I settled on using a 1/2 in AlTiN fine serrated rougher. I left 0.010 to clean-up with a conventional 1/4 AlTiN end mill. Super short stick-out on both allowed going pretty fast.

Thanks!

 

[surplusjohn]

I have made similar parts by laser cutting flat sheet and bending up two halves that telescope into each other. A few spot welds and your done. You get A very strong tube.