Bending stainless steel tube?

[AntarcticPilot]

My boaty nextdoor neighbour was a industal plumber, the big stuff like gunbarrel etc. He told me a story about how they used to amaze the new apprentices with majic. They would give a long lenght of pipe to the new guys to fit to a curved wall, and walk away. The apprentice after a few minutes would lay down a straight run of pipe, thinking it was necessary to get a pipe bender. But where do you get a bender for 3" gunbarrel?

Answer: apply heat from a oxyacetylene torch one just one side of the pipe, quite hot over most of the pipe and white hot in several places, and with practice you can get a constant radius curve.

Would it work with small dia. Pipe?

Interesting. I suppose you heat the outside of the bend, so the differential expansion of the metal forms the curve, and then fasten it in place before the metal cools? I can see why the apprentices didn't get it immediately

I'd have thought that for relatively narrow stainless tubing, there would be several snags with this - getting a heat differential between inside and outside of the bend would be difficult if not impossible, and if it was hot enough to work, wouldn't that potentially wreck the metallurgy of the stainless steel? You'd also be fastening in quite a lot of strain. I suspect that it would at the very least not be cosmetically very good - you'd get "blueing" and such like.

 

[uxb]

as long as the pipe wall is not heavy guage you will be able to bend a small radius such as 15 degs by hand in a vice

Gave that a try- I'll need a bigger, stronger vice. With bigger, stronger bolts holding it down.

I've blagged a loan of a pipe bender tomorrow so I should be able to make a mess of it with the correct tools

Thank you all for the assistance!

 

[Lakesailor]

Everything that I've read stresses that s/s work hardens, so you need to do it in one hit if you can.

 

[paul.norton]

The big problem with bending tube is going to be kinks on the inside of the bend unless you have exactly the correct formers.

However, there are old tricks like filling the tube with rammed sand etc. But, my late Dad, who worked in the aircraft industry before and during WWII, told me they would fill pipes to be bent with Wood's Metal.

Read all about it here:http://en.wikipedia.org/wiki/Woods_metal

Paul