Sheet Metal Repair, I hope = HELP

[Janderso]

Hey all,
I'm no body man. This is the belt guard for the old drill press.
I plan on sanding it, primer and a nice bright color finish.
I need to get the bend out first!
One of my coworkers suggested I cut the welds, straighten then reweld. I don't want to do that.
What if I clamp it down like shown, heat the area that is bent to a dull red and tap it with a rawhide hammer?
What say you?

Thanks for ideas.

 

[Steve-F]

That should work, but I would find a straight piece of metal and tap on "it" as a mandrel giving the cover a better chance of getting straight instead of a bunch of hammer hit marks, besides the rawhide will burn:<)

 

[lordbeezer]

Solid surface. Try with no heat. Big enough metal hammer.

 

[deakin]

as an old body man said to me many years ago " if it bent cold straighten it cold"

 

[Bob Korves]

Think about moving the metal while not stretching it. That is how you make/keep the metal flat or fitting into the original curves and shapes. Work slowly as you learn, thinking before pounding, making every push of the metal move the surfaces toward where you need them to be. It is possible to shrink stretched metal, but it usually takes heat, learning, practice, and some newbie mistakes... First. do no harm!

Edit: Have something like a bucking iron used for sheet metal work (or whatever) that is heavy and fits the back side of the metal to help prevent stretching it.

 

[Bi11Hudson]

Many long years ago I purchased a Horrible Fright body repair kit for that sort of thing. I don't do "body and fender" work, or even sheet metal. But the basics still apply and that's what I was looking for. The custom shaped hammers and dollies have worked well. I don't use heat and usually am interested only in dressing the surface enough to run the machine. When working metal, it tends to "stretch" when straightened. That is one point where I do use a torch. Heating and chilling will shrink sheet metal. It works, but hanged if I know how. Just one of those things you have to play with. Or ask a real body man the details. . .

.

 

[jwmelvin]

Hot metal is larger and softer than the surrounding not-hot metal. So the surrounding metal constrains the hot spot, applying compressive stress because of expansion of the hot metal. That stress is relieved to a degree by strain (movement) of the hot metal. Then when the hot spot cools, it shrinks and the strain resulting from conforming to the surroundings when hot and expanded means the now-cooled spot is smaller than before.

 

[Janderso]

Boy
I can see a learning curve with heating and cooling.
I like the gentle cold method

 

[Bob Korves]

Boy
I can see a learning curve with heating and cooling.
I like the gentle cold method

The bottom line is getting the metal back where it is supposed to be, not stretched, torn, or cracked. Make sure every move you make is working in getting all the metal where you want it. At first it will require a large amount of looking at it and studying how to repair it, a slow process. It gets better with time and with understanding what works and what just makes it worse....

 

[deakin]

on dolly=stretch, off dolly=shrink