Chassis

[robstone]

I am attempting to weld 1/8 inch steel plate to the metal on the tunnel. The metal on the tunnel looks like it is close to 1/8 inch but my welder wants to melt through it. I cut the temp back and it does not want to melt the 1/8 inch plate but does great on the tunnel metal. Any thoughts? Keep in mind I am still learning to MIG weld.

[Gary Hammond]

Hi Rob,

I've never welded with a mig. My experience is all with stick, oxy-acetylene, and tig. The problem is getting more heat to the thicker metal and less heat to the thinner metal at relatively the same time.

With either gas or tig welding this is accomplished by the angle of the torch and positioning the torch over the thicker metal longer and more frequently than over the thinner metal.

With stick welding, you can do a back and forth weave spending more time over the thicker metal and less time over the thinner. You also have slag to deal with, and the possibility of trapping some slag in the weld.

You might be able to use the weave process with a mig similar to the stick process. This would work best with shielding gas rather than with flux filled wire.

I think another approach with a gas shielded mig would be to lay a nice bead only on the thinner metal first to build it up, and then weld the bead to the thicker metal with more heat on a second pass. I frequently use this layering process with good results while tig welding.

Hope this helps. Like I said, my experience is all with other types of welders and not with mig.

Gary Hammond,

[doug]

having done a lot of mig welding, I would try to kinda do spot welds with the mig. weld short strings say about an inch skip a foot or so and do another inch, go back and start over where you stopped at and do it again until done.

[robstone]

I figured out what the problem is. Rust/rot. The tunnel metal is thinner in spots due to rust in the tunnel. Had to build up some spots with weld material. Ended up burning holes out wider in order to find good metal. Once I hit good metal, I slowly filled in the hole with weld metal.

[robstone]

It is a real pain keeping everything level/square/even/symetrical.

[Gary Hammond]

Hi Rob,

robstone said:

I figured out what the problem is. Rust/rot. The tunnel metal is thinner in spots due to rust in the tunnel. Had to build up some spots with weld material. Ended up burning holes out wider in order to find good metal. Once I hit good metal, I slowly filled in the hole with weld metal.

Yeah, rust doesn't weld!!

Had the same problem patching holes in my floor pan!!

Gary Hammond,