Spiraling Square Stock

I want to spiral some small square stock. Probably 1/4" and 3/8" dimension. What is the easiest practical way to do this? Hold one end in a vise and twist the other with a crescent? How do I keep the whole thing straight, or do I straighten it later? I want to spiral sections along a longer piece rather than spiral the whole length.

And when I do want to spiral the whole length, will it spiral equally along the length?

Steve

Reply to
SteveB
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I used to watch the pipefitters at Todd Shipyards in Seattle bend coils in steam pipes used to heat crude oil in the bottoms of tankers so it could be pumped out. They did it at red heat over a mandrel in a gigantic lathe and the pipe was fed through a holding device geared to the leadscrew so they got the desired spiral pitch.

There is a concept in physics called "entropy". If when you spiralled a piece of steel by hand, it naturally spirals equally along its whole length, this would be IMHO a violation of the laws of entropy. That's like saying if you chisel a line will it be straight.

Small bits of square stock are inexpensive. You can try your vise/wrench idea for yourself. I think you'll become frustrated, however.

Grant Erw> I want to spiral some small square stock. Probably 1/4" and 3/8" dimension.

Reply to
Grant Erwin

Grant Erwin wrote: used to heat crude oil in the bottoms of tankers so it could be pumped out.(clip) ^^^^^^^^^^^^ What you are describing, Grant, is a way of making helical coils. What I think Steve is looking for is twisted square stock, like that used as pickets in wrought iron railings. I have done lots of this, and it is pretty easy. You hold one end from rotating, in a vise, say, and twist the other end with a large wrench. A large double-handles tap wrench is best, because it balances the forces, so the metal stay straight. You need to slip a piece of water pipe over the square stock to keep it straight. If you need to twist only a section of a longer piece, let the material stick out the other side of the vise, and past your wrench.

I have also done it with an electric pipe threading machine. You weld a short square section at one end of your pipe, to apply torque to your square stock. You clamp the piece of pipe with the square end away from the rotating chuck. If you turn on the threader, the pipe and the square stock turn together. If you put a wrench on the stock where it comes out of the pipe and the chuck, you have the far end turning and the near end stopped, so you will make your spiral.

Yes, they come out uniform.

Reply to
Leo Lichtman

Most people doing this do it with the aid of heat. You'll get the twist only where you heat it.

John Martin

Reply to
JMartin957

You've got the right idea. A blacksmith does this with a two-handled wrench made for the purpose. A one-handled wrench, like a crescent wrench, doesn't work as well because the side forces can't be avoided. If you can't find or fashion a wrench with two handles, I suppose you could try two crescent wrenches, but I don't know how difficult it would be to keep them both on the work at the same time.

You can keep it fairly straight if you use a wrench as described above, but a little straightening is usually needed after also.

No problem. It's commonly done this way.

Not without care. By controlling the workpiece temperature carefully, in particular making certain that the portion to be twisted is uniformly heated, and by completing the turns quickly before the temperature gradient becomes too pronounced, you can achieve a remarkable degree of uniformity. With practice. (G) When the workpiece is much hotter in the center, then the center of the twist will be tighter.

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Cheers!

Jim

Reply to
Jim Wilson

I have to second what Mr. Lichtman said.

I twisted a bunch of 1/2" square stock a while ago. They were 18" long, both ends, 6" each were untouched, with the middle

6 inches with 3 twists. I put 6 inches in a vise, put a 6" 3/4" pipe as a spacer, butt up against the vise, and used a big f!@k off tap handle up against the pipe spacer. I used no heat...I was amazed how easily the stock twisted. The twists were perfectly uniform. I think if heat in the form of a rosebud was used, the end product would have irregular twists. You would need a furnace or something of the like to heat the piece uniformly.

FWIW, Jay

Reply to
Jay

My kids and I do this all the time (decorative twists in 3/8" sq. steel, that is).

Always done cold, because heating is unnecessary and too difficult to do evenly.

Can be done with a shifter, but its difficult to keep it straight and aligned (especially for 13 y.o. kids). I made a T-shaped jig, with a long crossbar-style handle and a pipe section that fits neatly over the area to be twisted. The rest (under the twist) is held in the vice.

Piece of cake. Dead easy. Perfectly uniform, too. Resist the temptation to twist too many turns. A couple will do.

If you (subsequently) want to twist the *whole* length, there is no way on God's earth you will get it even. Do all the twisting you want in one go, not in sections, unless irregularity in the twist doesn't matter.

Jeff

Reply to
A.Gent

I would think that you could do a reasonably good job by chucking the rod at both ends in a lathe within a pipe to maintain straightness and hand crank or use your back gearing to twist. This is just an untried suggestion.

C
Reply to
Carl

Carl wrote: (clip)chucking the rod at both ends in a lathe within a pipe to maintain straightness and hand crank or use your back gearing to twist (clip) ^^^^^^^^^^^^^ That comes very close to the method I described in an earlier post, using a pipe-threading machine, and I expect it would work perfctly well. I imagine that your lathe, with its gearing, has easily as much torque as my pipe threader did.

Reply to
Leo Lichtman

Reply to
Karl Vorwerk

Yes exactly Leo. Sorry, I hadn't read all the posts. The available torque from the 5 hp that I have is scary.

C
Reply to
Carl

Come to think of it I suppose the torque available from any lathe with the same hp and gearing would be the same. (0:

C
Reply to
Carl

Read the other posts but the key to keeping it straight is to keep in under tension. When you twist the stock, it will tend to shorten up. If you keep it the same length, it will be arrow straight.

For a short run you could clamp > I want to spiral some small square stock. Probably 1/4" and 3/8" dimension.

Reply to
Roy J

Sounds like a good idea. What is a "lathe?"

Just kidding. I don't have a lathe or any machining experience.

Steve

Reply to
SteveB

A friend of mine had to twist 20 foot lengths of 1/2" square. He used his small farm tractor. He made a "chuck" that fitted his PTO shaft. He clamped the 20 foot length of square bar to the chuck and slid an (almost) 20 foot section of half inch water pipe over the bar and clamped the other end of the bar to a post 20 feet away. He mounted a veeder-root counter on the back of the tractor so he could count revolutions of the PTO shaft. He fired up the tractor and, at an idle, gently engaged the PTO, letting it run until he had the required number of turns.

Done cold, you are assured of equally spaced twists (just don't start-stop). Done hot (as we blacksmiths often do it) you get a tight twist where it's hottest and less twist where it is cooler. This usually means that where the ends are suppported, they cool quicker and twist less. Part of our training is in teaching how to correct for these problems. One advantage of hot twisting is that one can make good looking tighter twists with heat.

Pete Stanaitis

------------------------ SteveB wrote:

Reply to
Pete & sheri

A good many years ago I saw the set up a guy used for his " Wrought " iron fence business. He used a small electric motor ( about 1/3 hp ) which drove a worm gear reducer. The output of the reducer drove a manual auto transmission. The square stock was dropped into a square three sided socket on both ends, the switch turned on, turns counted and switch turned off. They came out straight and with a uniform spiral.

Dan

Reply to
Dan Caster

Did a google search on "twisting+square+bar" Got some good ideas.

Reply to
Steve Cockerham

Leo wrote: That comes very close to the method I described in an earlier post, (clip) ^^^^^^^^^^^ Carl wrote: Yes exactly Leo. Sorry, I hadn't read all the posts (clip) ^^^^^^^^^^^^ And Leo responds: Carl, I wasn't accusing you of "trespassing." I only wanted to verify that your method would work. ^^^^^^^^^^^^

Reply to
Leo Lichtman

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