Cutting thin-wall tubing on a lathe

[55fairlane]

I do this sorta thing regularly.....A) use a collet B) use a thin bit parting tool C) turn a bushing from plastic that you can grab with a drill chuck, this will support the work

 

[tq60]

A knife works, look at tubing cutters.

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[homebrewed]

I like your solution . Tubing can be difficult to work.

I found this 1/8” wall x 6” or 7” OD acrylic to be pretty challenging. There is a piece of 1.775” steel as a mandrel, then centering disks plus 2” pvc pipe stacaked up and pushed hard against the chuck jaws (the tailstock center is in a close fitting sleeve to support the bar and it also provides the push to compress the pvc stack up). Then I can cut both ends in the same set up (the ends need to be parallel to each other, all 4 tubes have to be near the same length (about +/- 0.002” tolerance and as “square to the tube axis as can get it”). Miserably easy to chip.

Yeah depending on the job acrylic can be a bear to machine. Doesn't sound like much fun.

 

[homebrewed]

A knife works, look at tubing cutters.

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I was concerned that a tubing cutter style of setup would reduce the tubing ID on the end -- the pieces are a snug fit on a post as it is. But it turned out that my setup reduced the ID enough to cause problems, so I set up my tailstock to run a drill down the tube. It was about a #44 drill. This was 2.5mm OD tubing after all.

 

[homebrewed]

I do this sorta thing regularly.....A) use a collet B) use a thin bit parting tool C) turn a bushing from plastic that you can grab with a drill chuck, this will support the work

Yes, if only I had any collets that went down that small. This was a one-off thing so I was after a get-er-dun with a what-I-got solution.

That said, now that I have the fixture I want to refine it so it can accommodate different sizes. As it is right now, it's only good for cutting 2.5mm tubing. Boring out a larger hole and making some inserts would be the next-simplest approach.

 

[Smithdoor]

I need to make about 10 metal sleeves from 2.5mm OD thin-wall brass tubing. I made a custom travelling rest to support the tubing, so I can position my parting tool right where the tubing exits the rest (see photo below).

View attachment 485927
The hole is just a little larger than the tubing. My question is about the height of my parting blade. For this kind of situation is it best to have the blade slightly high, low, or dead-center on the tubing?

One refinement I'm thinking about is making a piece with a V groove in it, to support the tubing a little better. The piece would be run up to the tubing and fixed with a couple of screws. I _could_ mill a step in my vertical block, but I have some other plans for this thing once I'm done making my brass sleeves.

BTW I initially just positioned my parting tool very close to the chuck jaws but its 3-point grip didn't provide enough support for the tubing -- the ends of the tubing became deformed. These sleeves need to slip over a small post and there isn't much clearance. I was forced to ream out the ends of the tubing, not easy to do with a .250" long piece of 2.5mm tubing. That got old pretty quickly.

The cut off tool works great till you working with this tubing like is in photo.
A dreaml and a cut off works best.
A holder in lathe works the best for a good looking cut

Dave