View Full Version : Straightening Galvanized steel wire in a home shop

05-01-2006, 07:12 PM
Have to make up some steel wire trelisses for the other halfs plants in the garden. Dia is 3/16 or B&S gauge 6to 2 the steel is coiled at most of the local joints that sell. Need to make the wire straight for the radials from the ground to the arc or the circle at the the top of it. longest section would be about 6ft.

Forrest Addy
05-01-2006, 08:14 PM
Best way to straighten wire on a small scale is to pull it until it yields. If the wire is soft it will yield at about 2000 lb. If the wire is the spring temper tension wire used in cyclone fences it will yield at 5000 lb.

It sounds more complicated than it really is. If you have two large trees or utility poles separated by some distance like 50 feet and a 3 ton chain hoist you can stretch a long length at a time. You will need to protect the bark of the tree with sandbag padding and many slats of wood. Use 1/4" chain for the rig and cable clamps to hold the bight of the wire. Stretch the wire about 5%.

If you wish to straighten it with a tensioning jig you need double the pull because you'll stretch the wire doubled. It's simpler that way. So you need a 10 to ton bottle jack.

Got a 6 ft long piece of 3" pipe? File a notch across one end to make a saddle so the wire doesn't slip off. Stack the jack on top of the pipe. Mount a Piece of 3" wide 3/4" thick plate that's 1 1/2" longer than the jack is wide on top of the jack. Call this piece of plate the "saddle." Round over the corner where the wire will bend.

Set the pipe up vertically and clamp it to a porch or the bumper of a pick-up so you can work the job vertically. Rough straighten a piece of your wire about 14 ft long. In the center bend a square double corner to fit the end of the pipe. Run the free ends of the wire up the pipe through two of the holes in opposite ends of the saddle. Fit the loop into the notches. While holding the saddle in position place the jack on top of the pipe and place the saddle on top of the jack. Have a helper hold things in position while you work. Keeping the slack out of the wire and the saddle level, bend each wire so is passes over the top of the saddle so it crosses the saddle from opposite sides. Cable clamp the wire where it crosses the saddle. Use at least three cable clamps and tighten the snot out of them.

Operate the jack. If the wire breaks under tension the whole set up may jump and scare you but it will not react with a violent Hollywood-style explosion. Tension the wire. When it straightens out, work the jack two more inches. Relax the tension for a check. If the wire is still wavy stretch it an inch at a time until its straight.

Cut the bends off the wire and set up for the next pull.

05-01-2006, 09:27 PM
Simple, tie one end to something solid, chuck the other end in a drill motor, pull and pull the trigger, be straight in a flash.

05-01-2006, 10:34 PM
Just a little warning about using utility poles as anchors. There is no way a visual inspection will guarantee a solid pole. (Even if you do know how to test for rot, you probably shouldn`t be doing it ...the pole is owned by someone else after all.) Putting a high stress on the base of a rotten pole might end up breaking the pole off and possibly dropping high voltage lines on yourself or others if it`s an electrical utility pole, not to mention the outage and costs that you will incure. They can stand for a long time with just a thin outer shell of wood left, but a stress imposed on one side can cause it to collapse easily. It`s sort of like a pop can, strong as long as you don`t dent it. Trust me..I have seen poles that looked like new on the outside but were totally rotten inside and many poles that were rotten but looked to be in excellent condition.

Forrest Addy
05-01-2006, 11:00 PM
Arcane makes an excellent point. I withdraw my suggestion. Better use large sound trees.

05-01-2006, 11:03 PM
So, what Forest said. Forget the tree (pole?), tie a short 12 foot piece of wire between two stout trailer hitches mounted on pickups and pulling against one another. The heavier the pickups/trucks, the better.

Tighten the wire slowly, then give a 'jank' for about the last 10 inches of travel prior the wire tightening. (One jank equals half a yank plus a half jerk). If the wire breaks you've probably exceeded the yield strength resulting in the two pieces of pretty straight wire. If you are happy with the wire straightness before breaking, all the better. If not, try increasing the length of the janks. Not as exciting as pulling over a rotten pole, but sort of like un-hammering a long, skinny nail.


Frank Ford
05-02-2006, 12:12 AM
I guess I'd be inclined to pony up four bucks each for nice straight six foot pieces from McMaster. In fact, their price is a bit lower for 1/4" diameter.

Failing that, how about tying a long section between that pair of stout trees? Tie it as tightly as possible, and then pull it outward in the middle with your choice of devices. Lots of mechanical advantage, so you get more stretch for your money. I've done it with lighter wire just pulling by hand.

05-02-2006, 12:30 AM
We used to pull it through two pieces of oak clamped in a vise. use about 8 in long pieces.

05-02-2006, 01:33 AM
If you use a tree to straighten the wire protect the tree so the wire doesn't cut through the bark. Just below the bark is the cambium layer. If you cut that you kill the tree. It is where all the water and nutrients flow and it is very thin and easily damaged.

05-02-2006, 01:37 AM
The last time I straightened wire, I used a pair of 2x4s. Put end to end, that came to 16 feet long. If you lift one end up, the distance between the ends gets shorter. Anchor the wire to both ends, then press down on the raised 2x4 and the wire will be in tension. If you get the geometry right, you'll be able to put enough tension on the wire to stretch it. If you don't get enough stretch with the first setup, just put some thin scrap between the 2x4 ends to space them further apart and go again. If you can't put enough tension on the wire to stretch it, you have too much angle.

I laid a piece of metal across the outer end of each 2x4 so I could wrap the wire around the ends and over to the back side, where I had vice grips temporarily screwed down, and that seemed to hold the wire ok without slipping. The wire forms two corners where it wraps around the metal piece, and those corners take up a lot of the tension so the vice grips don't have to grip as hard as they might have to otherwise.

It would help to have a friend help out, but if you do this yourself, you can do it in your driveway. Drive one tire up onto one end of one 2x4, after the wire is attached, and that will hold that end for you. If you position a couple small pieces of 2x4 properly, you won't have the weight of the vehicle squishing your vice grips.

My job was making 200 custom curtain hooks for a stage curtain, and I used some galvanized which I believe was .1 inch diameter, and I was able to get it straightened this way.

In hindsight, I would have used 2x6s as they would have had less tendency to swing sideways. You do have to be careful to keep the alignment as you're doing this stretching.

Mike Burdick
05-02-2006, 02:38 AM

When you get the trellises made how about posting a couple of photos?

05-02-2006, 06:23 AM
Thanks one and all for your responses Will be thinking on it as to the best way to do it solo. Will check out McC and if they come out ok will post other wise like a doctor I bury my mistakes :D