Looking to see if anyone has tried to twist 2" thinwall square tubing.
I have a project where I need to put a twist into about a three foot
lengths of 2" square tube.
I'm thinking that if I insert a loose fitting round pipe inside the
square tube and would then pack the tube with sand and weld caps on
each end that this would stop the tubing from buckling. I have a large
old pipe threader which I'm going to try and do this cold also since it
is rather large of an area to try and heat up uniformly at once.
Any thoughts or other ideas and practical experience would be
I haven't twisted tube, just flat or massive square. The trick to use some
tube to keep the thing straight is right.
In your case, I'd put just some round inside of your square tube. No sand,
no caps. If you weld on caps, you need much more force and the twist won't
You could also slip some round tube over your square tube if you haven't
something that fits inside. Doesn't make a difference.
And mebbe heat it up w/ a rosebud O/A tip.
Sposedly yer not sposed to use rosebuds on B tanks, but if you have a flash
suppressor in line, doing it on a full tank should be OK. I've done it.
Or preheat some other way.
Mr. P.V.'d (formerly Droll Troll), Yonkers, NY
It will twist nicely if you keep it under tension. Doing that is a bit
tricky. Find some 2-1/2" x .250" wall square tube, cut some 1/2" slices,
weld these over the 2" tube. make a 3' long fixture out of 2 pieces of
heavy wall 2" pipe (or similar strength) along with some end caps. You
will need to shim the end caps to start the twisting with the tube held
snugly. Putting enough torque on it is your problem!
I've done it with smaller thinwall steel by putting a bolt through
holes in either end and mounting one set firmly to my work table, then
taking the burner out of my forge and giving it a couple of passes with
that, but it has a tendency to spiral at the same time. I think that if
I were able to put it under tension as suggested above that that might
not happen. You could probably wind up doing just as well by fitting a
round pipe down the middle and putting the bolt through just beyond it.
If it begins to scrape too much, heat the whole thing up and stretch it
out a little, let it cool some and try again. Can't promise all that
much for strength, but it would probably do for decorative work, which,
since you haven't mentioned concerns about the seams weakening, I guess
is what you're up to. Just dont heat
it too much, and
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