How long is the tube? Can you turn a bung from a piece of hard wood? Push the tube firmly onto the bung and go from there.Wood is messy to turn though, so mention it to the lathe's owner if that's not you.

A common method with cutting plastic pipes, e.g. underground waste pipes, is to wrap a piece of paper around the pipe so that the edge lines up where the paper overlaps. On your 54 mm copper the same method would probably work. Once positioned, hold the paper from moving and go over the edge all round with a Sharpie. Then remove the paper and cut at the edge of the Sharpie mark. I reckon the result would be accurate enough, assuming that you're going to fit an end disk with a soft or hard soldered joint.

If it had to be a lathe job, the fixed steady rest could help but I'd regard cutting thin copper tube with a parting tool as quite an adventure!!!!!!!! Filling the tube with a wooden bung (or maybe even Plaster of Paris) sounds like a good idea.

When you've done the job, please come back and show us a few photos of the result.

Best regards,

Swarf, Mostly!

A large V block or couple of angle plates could hold the tube square to a surface plate and then scribe a line all the way round, once marked out you should be able to carefully file to the line  which should be then be pretty square.

Mike

Edited By Mike Poole on 13/11/2020 17:37:26

Further to the excellent answers already given, once you have cut your slice of material from the tube place a sheet of abrasive paper on a flat surface. Using circular and figure-of-eight motions true up the ends of the part. Check your progress frequently with an engineer's square.

May not be quite the same thing, but some time ago I was asked to provide a large number of 3/4" copper tube short lengths 1" long. No idea what they were for, I dont even ask !

I did it by mounting the tube in the chuck and supporting the overhang using a suitable plug held in the tailstock and parted off. The pieces remain on the support when cut and are easy to collect, no rooting in the swarf to find them.

I understand that this would not work in your case, not many lathes have a spindle bore that size, but might be of interest to others,

PS, The old "Paper around the tube " is an old trick, but it still works !

… On the other hand, I have a plumbers, eclipse pipe cutting wheel, that cuts 54mm OK & that cuts copper pipe nice & square. Can you borrow one?…

+1 … the easiest solution. I have a smaller version that will do up to 22mm copper pipe bought from local M/Mart; usual disclaimer.

George.

Lynne, I like that idea ! never thought of that one, so, learn something new every day.

Has Anyone ever adapted a tubing cutter to take a parting tool?

The paper wrap method is the one I use.

I don't think there was a problem with a pipe cutter if you have one that will do that diameter. Most other suggestions were ways of doing it without spending money on a tool that will only be used once.

Martin C

Haha. Brilliant. Maybe those old guys did know a trick or two after all!

Another trick to mark pipes square that old boilermakers used was the previously mentioned wrapping a bit of paper around the pipe, but using a readily available strip of emery tape as the piece of paper. The 2" wide stuff works well for full sized pipework diameters.

Edited By Hopper on 21/12/2020 09:38:31

A length of shim steel or brass works very well held in place with a jubilee clip on round tube. Using the paper trick also works on box section as well. Noel