Weld distortion.

[Shield Arc]

I was in a discussion about welding warping square tube over on Welding Web, another member posted this video from Lincoln. I never seen it before, thought it was great,:thumbsup: also thought some of the members here may not have seen it too. Hope you enjoy it!

Prevention and Control of Distortion in Arc Welding - YouTube

 

[GPintheMitten]

Thanks. That was interesting both from a technical aspect and the Disney cartoon style of presentation.

 

[Industrial Toys]

Very interesting. I'm still having a hard time understanding why the direction of shrink is so counter intuitive. You weld the one plate onto the other in a T and I would think the standing one should bend away from you as the metal by the weld expands, not come toward you. It always strikes me as weird!

Why not weld one end first a little, then go right to the far end and do a little there keeping any one area from getting too hot or spreading apart too much?

Generally I try to tack everything together first.

Trying to get out of the habit of using way too much filler!

 

[bikerdib]

Thanks for the link. Very interesting.

Mr. Shrink... LOL

 

[Shield Arc]

Very interesting. I'm still having a hard time understanding why the direction of shrink is so counter intuitive. You weld the one plate onto the other in a T and I would think the standing one should bend away from you as the metal by the weld expands, not come toward you. It always strikes me as weird!

Why not weld one end first a little, then go right to the far end and do a little there keeping any one area from getting too hot or spreading apart too much?

Generally I try to tack everything together first.

Trying to get out of the habit of using way too much filler!

It does to a degree. But the metal will contract / shrink / pull more when it cools. The weld pulls the top plate towards the side that is welded. I would tack two to three places on the opposite side of the weld.
I always tack everything first. I always back step, and skip around a lot with my welding. Very seldom do I pre-bend before welding. I try my best to control warping with weld sequence. If it doesn't work, I'm pretty good with heat shrinking metal.

 

[bikerdib]

Depending on the job, I have used the "anticipate the shrinkage" method and placed the pieces so the shrinkage will pull the material straight but I usually either under estimate or over estimate. It's kind of witchcraft to get it perfect. I never tried pre bending. I usually just clamp the pieces in place, tack, weld (sometimes using the alternate weld method) and leave clamped till cool.

 

[bikerdib]

Shield Arc, how many of those SA-200s run?

 

[Shield Arc]

Shield Arc, how many of those SA-200s run?

Right now only three of them. One is almost taken all the way apart to paint. The other one I haven't touched since I bought it.

 

[Mark @ Everlast]

They can't make common sense, simple videos like that anymore. Nowadays, they'd have some guy with a Dr's degree in metallurgy explaining in detail the expasion of molecules and providing formulas for figuring the exact amount of expansion and the precise angles needed and swamp you with the science and the math without ever telling you exactly what you need to do.

 

[camshawn]

Thanks for the link. That was a good simple video. Now if I was just a little more patient........

 

[Gem99ultra]

Excellent video Shield Arc! Thanks - and yes, I did learn a lot from it.

 

[Industrial Toys]

I'm sure any modern video would concern itself mostly with safety. Don't wear your flipflops when welding or don't put your tongue on the hot steel! I'm surprised nothing is said of tacking. Is that more phenomena made popular by mig welding? What amazes me, is that the expansion and contraction forces and significant, yet can be held in check by mere tacking.