Supporting Rectangular tube in rotary plasma?

[Econdron]

I've seen all sorts of simple, easy to use supports for round tubing, even some that work for square tubing, but I'm looking to cut some relatively long lengths of 2x3 rectangular tube, like around 70" L that need various notches, etc cut from them. How can I support this? I had a few ideas, best idea I can come up with is to make something like a tailstock center on the opposite end, then make a rectangular cap that will fit around the tube with a hole through the center for the tailstock to support. Does that seem like it would work? Any other ideas?

[acourtjester]

I assume you at talking about a manual turning device so you can cut on the top surface the turn for another side.
I would incorporate a locking device to hold each surface level while cutting. Ohmic sensor will take care of different side heights.

[Econdron]

No, 4th axis CNC controlled chuck on the other end. If I was just manually turning and cutting the flat sides I would just lay the tube on the slats.

[tcaudle]

Supporting long lengths of square tubing is not as easy as round. You have to make it look round to the fixture. It means having a square to round adapter (s) that either clamp on the material and the torch moves u p and down the length ( while not hitting any of the adapters OR having the rotary axis shove the tube through a stationary adapter at the torch. OR have a end post to support the wild end (like a normal lathe )

[Larry83301]

We made several different size square tubing holders just using a 4-jaw chuck from an old lathe.


Larry

[Rodw]

If you were going to use a chuck, you could consider using a 4 jaw self centreing chuck. If you are holding a rectangle, you'd just need some packers to put on the narrow sides. Thats what I have in the back of my mind. You would not need many packers as there are not many RHS sections anyway.

[acourtjester]

here is a simple way to do it.
https://www.youtube.com/watch?v=mSknlq9YK54&t=2s
or the more money solution
https://www.youtube.com/watch?v=kcSWXSfYqAs

[Rodw]

Might not be something exactly what you want but I thought this could be adapted to a plasma machine for a rotary axis

http://ravenview.com/blog/2010/10/17/ho ... rth-chuck/

[Econdron]

here is a simple way to do it.
https://www.youtube.com/watch?v=mSknlq9YK54&t=2s
or the more money solution
https://www.youtube.com/watch?v=kcSWXSfYqAs

I'm not sure you understood my original question. I need to make cuts on rectangular tubing that wraps around the tube. I have a CNC controlled chuck on one end, I am just looking for a simple solution to support the other of long sections. Short sections I can just tighten in the chuck and cut away without it sagging too much, but a 70" L piece definitely needs the support on the other end.

Like Tom said, I think a tailstock on the far end with a cap over the top is probably the easiest way to do it.

[steel 35]

If you make a cut that wraps around the tubing what good is the tail stock going to be?

[acourtjester]

Well the second video show how somebody did it, looks like a simple 4 jaw chuck which allows the square tube to rotate and cut on the edges.
With that the main thing is having a THC that can follow. CandCNC had a video showing them cutting corrugated metal using their DTHC.
You could make a jig to attach to the end of your tubing that has a small center hole where your tail stock could attach and allow the tube of move around a center point. Like a live center on a lathe. Your half way there with the motor driven chuck.

[tcaudle]

The Rotary Plasma Plugin for SheetCAM cuts round, square or I-Beam shapes. It handles the 4 axis and lifts the Z on the corners to get an continuous cut.