Yield strength question

My SWAG = .013 in^2 x 10000 to 15000 psi = 130 to 200 pounds tension to straighten the wire.

Ned Simmons

Hi Ed,

Try clamping one end and chucking the other in a drill. Pull a little tension on it and twist the wire with the drill while pulling slightly. There's more than one direction you can yield the wire in.

Tom Lipton

I agree with your math, but the yield could be as high as 30kpsi depending on what the alloy is.

Best way to straighten it is to put a l> >

Fab up a roller straightener. See ebay item 7527787746 for a not-great picture of one on a Eubanks wire cutter/stripper, on the front left corner of this machine. These use 4 rollers over 5 rollers followed by

4 rollers beside 5 to straighten in both planes, with a screw to set how close the rows of rollers are to control how much the wire gets bent back and forth. On our Eubanks I aim for maybe 1/2 the overall wire diameter deflection when feeding 14 ga insulated wire and it comes out pretty straight. More deflection would be straighter but the pulling resistance gets out of hand and we don't need it any straighter :-). For a quick-and-dirty setup just use some small pulleys, maybe .75-1" diameter, and start with just one plane, to see if it will do your job.

-- Regards, Carl Ijames carl.ijames at verizon.net

Think slide hammer.

Ken.

It's ground wire, probably alloy 1100-O, so even 10ksi may be high.

Ned Simmons

The problem with just plain tension is that the wire will not reach the yield stress along its full length at the same time. It will probably start to elongate in some areas before others. A part that started out nearly straight may still have its original curvature after you're through, while other areas could actually neck down.

"Steamer"

I like all the replies given so far. I straighten alot of copper wire in

8 foot lengths. My copper is possibly enough different from the characteristics of the aluminum you have that this wont be beneficial to you. But. Any of the slight bends that dont straighten by pulling can be straightened quite well by rolling the wire on the clean garage floor while tapping the wire with a plastic (dead) hammer.

Jerry

Hi Ed, I inherited a rod straightener with a shop stock that I bought years ago. It consisted of two sets of three closely spaced ball bearings installed at right angles to each other. The middle bearings had a screw adjustment to change the tension. The whole thing was mounted on a 6" X 8" plate that could be clamped in a vise. It would straighten coiled rod stock dead straight for a fabrication operation by drawing through the bearing set. The term you were looking for is the yield point. ____O__O_____ O [Crude drawing} Bugs

I have done it with #10 steel wire. Clamped off one end to an eye bolt on the wall across from the big vice, tied the other to the wide open vice jaw and then closed the vice. May take a couple of cycles. Just keep stretching and shortening up until you get a smooth cantenary when you slack off. Aside from some ominous creaking from the shop walls it works great.. #8 aluminum should be a piece of cake.

You got it!!eggzakly right--I use a pr. of visegrips & twist the wire around them one more time..set up a good pull (you got a heavy vise doncha?)--then whack the pliers with a 2# shop hammer---works for me- I straightened some 3/16" S.S. tubing this way. JERRY

>

The wire straighteners that I'm familiar with were rows of ball bearing assemblies (maybe 10 pair) with grooves in the outer races. They were for steel wire that was payed out from large reels, and were adjusted to just slightly under the wire diameter. These were very effective for wire mill production.

I've seen it mentioned several times that numerous folks have used 2 boards lightly clamped together to pull the wire thru. Some were wanting to straighten piano wire, and used a drill to rotate the wire as they pulled it thru the boards (although they weren't taking it off spools). I haven't tried this method, but it would likely be a low cost plan. 2 pairs of boards oriented horizontal and vertical should be fairly easy to set up. A shallow groove should be enough to guide the wire. If the wire pays out from the coiled diameter straight into the groove, it should be fairly easy pulling.

WB .............

--Thanks to all; a number of good ideas! I'll buy the material and take a whack at this today and report back tonight. I really only need relatively straight lengths of maybe 10ft. so I'm thinking the slide hammer and hand drill approaches are worth a whack, so to speak. WHat I'm aiming to make is stuff that I can bend around a form, to make an "armature" that matches the outline of a "two decker" sail-era warship. I've got to make a dozen that match, each about 2ft long and maybe the same in height. I figure I'll make the form out of a hunk of plywood with nails at corners and bandsawn bits of MDF for the curvy parts. When I'm done these 12 will be covered with EL wire, then positioned on a grid. The EL wire on each individual ship will run to a separate channel on a sequencer, so that the ship appears to be "sailing" on a "sea" which is also sequenced, but in a slightly different scheme. I've got the "sea" done and it works pretty neat. Ships next...

One type of straightener I've seen in some mechanic's kinks books is a piece of tubing bent in a lazy "Z" shape, like 10 or 15 degrees off axis for both ends. I've used this in EMT for thin wire(#16 copper), bent with an EMT bender, it worked. Just pull the wire through and it gets straightened out. For 8 gauge, you might want to go to 2" tubing. I've seen a similar thing using wooden cleats nailed to a support board, the path was the same. Probably wouldn't last as long as the tubing, though.

Let us know what works.

Stan

What is EL wire?

Don Foreman wrote: : What is EL wire? --Electroluminescent wire that mimics neon tubing, but is bendable, solderable, etc. Very neat stuff. There are a number of folks that sell it but my favorite is coolneon.com because they have "soldering parties" where they show you how to work with the stuff; they have sales then too and they extend bigger price breaks for quantity buys.

[ ... ]

Unfortunately, on a fixed-pitch font, it shows up with the lower roller to the right of both other ones. I somehow doubt that was what you intended.

Better to switch to a fixed-pitch font before drawing something, and then *warn* people to read it with fixed-pitch as well, because different proportional pitch fonts (or the same proportional pitch fonts on different machines) behave differently, so your "drawing" is likely to be distorted on various screens, and not show what you intended. I'll try to change it so it looks right with a fixed pitch, and you can see how far off it looks on your proportional pitch font.

____O___O_____ O

I added one more underscore between the two top rollers to allow the bottom one to be properly centered.

Now that you have seen how bad it looks, select a fixed-pitch font like Courier for your newsreader, and see what it looks like. (And what your original looks like, for that matter. :-)

Enjoy, DoN.

--Current status update: aluminum grounding wire is now outlawed in Sonoma County so it's unobtanium; couldn't even find it at the local junkyard! OTOH I *did* snag 2lbs of aluminum welding rod for five bucks. It seems to be bendable, if in short 36" lengths. Have ordered 100ft of the grounding wire from coolneon in Oakland and hope to take delivery one day soon...

--Got the 1/8" dia. stuff yesterday afternoon; will try to pull maybe a 20ft hunk today and will let y'all know how it goes.