Best way to straighten annealed copper tubing

[GreensandsParticipant @greensands]

Can anyone suggest the best way to straighten short lengths of bendable annealed copper tubing as typically supplied in the form of a coiled loop? The size of piping involved is 5/16” O/D and working lengths range from 4” to 6”.

[bernard towersParticipant @bernardtowers37738]

steel bar to fit the inside dia with rounded ends, slide in as far as you can then roll between two pieces of MDF sheet then push in some more  and repeat.

[Trevor Drabble 1Participant @trevordrabble1]

<p style=”text-align: left;”>A pyro straightener available from reputable electrical wholesalers .</p>

[Nick WheelerParticipant @nickwheeler]

The grooves in the clamping faces of a Workmate do an excellent job of straightening nearly a metre at a time.

[noel shelleyParticipant @noelshelley55608]

I’d use the method Bernard mentioned, Simple for that sort of length. Noel.

[John PurdyParticipant @johnpurdy78347]

I used Bernard’s method for the 3/8″ dia. tubes for my 5″ga. loco boiler and it worked very well. They were about 8″ long.

John

[Bo’sunParticipant @bosun58570]

As John confirms, Bernard’s idea works great, and as he says, “Just rinse and repeat”.

[ChrisLHParticipant @chrislh]

I used the method I found on utube for coiled 12 mm OD copper tube about 3 m. long. Grip one end in vice jaws the other with Mole grips and wack the Mole grips. It wasn’t perfect but surprisingly effective. You do, of course, loose the flatened tube at each end.

[John PurdyParticipant @johnpurdy78347]

I’ve also used the method Chris mentions for longer lengths, 3 to 5 feet, of 1/8″ to 1/4″ tubing with good success but it doesn’t work very well for the short lengths Greensands is trying to straighten.

John

[Nigel Graham 2Participant @nigelgraham2]

I recall one method, for longer lengths, I think used by a Model Steam Road Vehicle Society member.

He suspended the tube vertically from some suitable point, with a weight on the lower end. Not so heavy it started to draw the tube down, of course, but enough to pull it straight.

 

 

[Charles LamontParticipant @charleslamont71117]

Uncoil and cut a suitable length, probably needs to be at least a couple of feet, and when straight enough to do so, roll it back and forth on a flat surface with the hands. I was gobsmacked when I first saw it done.

[Clive Brown 1Participant @clivebrown1]

Was it Tubal Cain who described using his Myford 7? Solder a suitable stopper to one end of the tube. Pass the other end through the tailstock and grip in the chuck, probably with suitable internal support. Wind the tailstock barrel away from the chuck to just stretch the tube sufficently to straighten it.

Can’t use a self ejecting tailstock of course.

[Martin KyteParticipant @martinkyte99762]

There used to be a tool for straightening mineral cable. Essentially it was a series of rollers, 3 on one side 2 on the other grooved to suit the cable diameter. The rollers were held on two plates that could be adjusted as to separation. You basically ran the tool up and down the cable at various orientations until you got everything straight.

Cable tool

 

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