Hopefully There are no Dumb Questions

bigtiller · Dec 29, 2018

Oldoak said:
No, it doesn't matter as to the seam's orientation. You can marginalize the warping by clamping both ends of the tubing down to the welding table while making your welds and keeping it clamped until the metal assembly has completely cooled down.

If any warping does occur, you can reduce it or even eliminate it by heating the back side of the arch with a torch and cooling that side down with a very wet rag in the area of the highest arch point. Sometimes it takes repeated efforts.

Another dumb question..... which side is the back side of the arch? Concave or convex.

WranglerX · Dec 29, 2018

bigtiller said:
Another dumb question..... which side is the back side of the arch? Concave or convex.

Convex.... IF you want to have straight beam, you need to shrink convex side...

Dale

Gordon Gould · Dec 29, 2018

The way I think of it is that you heat the side that makes the problem worse when that side expands from the heat. It seems backwards but, the heated metal compresses or crushes together when it gets hot enough to deform because it is restrained by the cool surrounding metal then when it is cooled quickly it freezes in the compressed position and ends up smaller than it was at room temperature which pulls the piece the other way.

gg

TMGT · Dec 31, 2018

And there always good old persuasion. I had to straighten this 3x3 .120 wall tubing. It had pulled almost 1/8" and needed to be 1/32nd or less, a little creativity and it was back to spot on.

I asked a very talented fabricator friend, that I've seen use the heat and cool method to straighten large stainless pipe, about the best way to straighten this and he suggested trying to bend it back cold first.

Big Barn · Jan 9, 2019

Nothing to do with deformation, but I always try to put the seam side down or facing inwards if possible.

If a glossy paint finish is used a slight indentation is always visible.

TMGT · Jan 9, 2019

Big Barn said:
Nothing to do with deformation, but I always try to put the seam side down or facing inwards if possible.

View attachment 586522

If a glossy paint finish is used a slight indentation is always visible.

View attachment 586525

Same here, except when you assemble something and realize you put the seam up instead of down but theres no way you're getting it back appart to fix before welding. Not that I didn't just do this a couple days ago..................