What material does a weld not stick to?

[sixdogs]

Still unable to post a picture so try to visualize. I'm building a light duty cultivator and have some 2" x 2" equal angle iron that's 3/8" thick and 7 ft long. It has a line of 3/8" holes punched an inch apart the length of it. The problem is, the guy that got these first had other ideas and cut the pieces in half. Then he re-welded them but got the pieces crooked and I need to start over.

My plan is to cut them in half again on the weld and then weld again but get things straight. Since I need to get the holes spaced correctly I plan to use a short length of the same stock that I have and bolt the two pieces to this. It will assure the holes will line up plus will stay flat as I weld it.

The question is, what can I put between the pieces to keep any weld from sticking to the spacing piece? Is it copper, brass aluminum or all of them? Since the surface will be tight together, a thin sheet would do it. I've never done this.

Also, since I'm bolting the two halves to the spacing piece, can I just weld one side and then flip it over or will the heat try to warp it and should I do something different?

 

[pat32rf]

I have some 1/4" x 4" copper electrical buss bar that I use for jobs like this. I have some aluminium bar as well but always grab the copper. It carries the heat away and normal 6011, 7014, etc won't stick to it.
Can you shorten them by 1" to get a nice square end when you cut the old weld out? This would still keep the 1" spacing...

 

[Ed of all trades]

It would be better to use spacers so your weld is away from the backing piece. Ed

 

[sixdogs]

I have some 1/4" x 4" copper electrical buss bar that I use for jobs like this. I have some aluminium bar as well but always grab the copper. It carries the heat away and normal 6011, 7014, etc won't stick to it.
Can you shorten them by 1" to get a nice square end when you cut the old weld out? This would still keep the 1" spacing...

Yes, I could cut it square. Am going to MIG weld it.

It would be better to use spacers so your weld is away from the backing piece. Ed

How thick of a spacer? I like that idea better.

 

[pat32rf]

I try to keep the weld tight to the copper so it removes the heat and gives a flat surface to the steel where it meets the copper. If you use spacers then you could use a steel backing plate then grind it smooth...

 

[bigdeano]

Steel weld won't stick to aluminum. I've made welding fixtures from alum and the welding splatter doesn't stick to it.

 

[LD1]

Copper works very well. Use it all the time filling in old bolt holes or pin holes that are wore out so I can re-drill them.

I don't like aluminum. Mig weld will stick to it, and it will melt and just be an ugly mess.

 

[Shield Arc]

Here at home I have different thickness of copper plates. On the job we've used Ceramic backing bars. It's funny to watch the puddle when it hits the ceramic backing. It acts like its laying up against glass.
Standard Non-Metallic Weld Backings for Full Penetration Welding - CERBACO LTD.

 

[Ed of all trades]

How thick of a spacer? I like that idea better.[/QUOTE]

Almost anything, 1/4" would work fine, just needs to be thick enough to give you some space. Ed

 

[Mysfyt]

Keeping it straight will be the challenge. How much tolerance do you have?