Tig **** welding sheet steel - panel alignment issues

[Tommy2Tone]

I am welding in new metal to fix rust holes along the front edge of my bronco hood. There is no backside access. Even though I tack the panels every half inch with perfect alignment and flush surfaces, when I do the weld they move and become not co-planar. Is there any way to prevent this or any suggestions on what to do when it starts happening? Thank you.

 

[zmotorsports]

It's best if you can get behind the outer panel to back up with a dolly to allow planishing of the weld but that isn't always possible.

For those that are not accessible, if you are using MIG, I suggest doing a test panel or two or ten to get the welder's settings just right. I have found that a hotter faster weld that will provide 100% penetration will be a much stronger and better weld to grind and finish in the long run. Many times people think that because it is thin sheet metal then need to turn the welder down but that comes at a cost of improper penetration that can come back to bite you in the *** in the long run, especially when you try to knock the top of the weld down.

As for the process, I keep as tight a seam as possible and then hit the seam evenly so that the current that is being provided at the wire is split between the two panels. If you hit only one side, the current required to melt the wire will all be on that panel so it is best to split it. Once the spot weld is done, move an inch or so and repeat. I then come back and knock the top of the weld tack down with a 1/16" thick grinding/cutoff wheel to where it just barely stands proud of the parent material. Then tack again with a full penetration weld at the edge of the previous one advancing forward by half a tack diameter. Knock down with cutoff disc to just above proud and keep repeating until it is a solid weld then go back with a Roloc disc and blend. Be careful not to contact the parent material any more than necessary as this just thins the parent material as you are removing metal.

If you are using TIG, then I use a similar process but it may require a bit more bumping around with a hammer to keep the panels in alignment but the knocking down of the weld and then metal finishing will be the same.

Hope that all makes sense.

I show some examples of this on my son's WJ repair in my Projects 2.0 thread starting on page 175-176 where I had to remove some rusted metal from a couple of areas and weld in new metal before finishing and painting.


**I apologize, on edit, I looked in the body of the message whether you were referring to TIG or MIG but didn't see anything specific. I later noticed in the title that you were referring to TIG.

If I have access to the backside of the panel I really prefer to TIG weld the panels as the planishing makes a really nice quality finished product with very little grinding and metal removal. Plus it is easier to compensate for panel movement where it shrinks you can planish and stretch it back into shape.

 

[theoldwizard1]

I don't remember what they are called or who sold them (Eastwood ?) but there is a type of clamp you can fit through the gap between the old and new panel that will keep them aligned. Your gap will be larger.

You can also "spot weld" a tab to the original panel that will hold the new panel flush. Use weld through primer or you will have immediate rusty issues.

EDIT : They are called **** WELD CLAMPS

 

[theoldwizard1]

You can also buy a hand or pneumatic flanging tool. Make a recessed flange around the old opening. Cut the replacement panel to overlap the flange. Weld

 

[brownbagg]

I don't remember what they are called or who sold them (Eastwood ?) but there is a type of clamp you can fit through the gap between the old and new panel that will keep them aligned. Your gap will be larger.

You can also "spot weld" a tab to the original panel that will hold the new panel flush. Use weld through primer or you will have immediate rusty issues.

EDIT : They are called **** WELD CLAMPS

harbor freight has them too, cheap

 

[zmotorsports]

You can also buy a hand or pneumatic flanging tool. Make a recessed flange around the old opening. Cut the replacement panel to overlap the flange.


EDIT : They are called **** WELD CLAMPS

Personally, I'm not a fan of panel flanging when welding in patch panels. This creates a double thickness of material in the area of the repair and worst case scenario it creates an area where moisture can get between and start the corrosion process, and best case scenario is that due to the panel expanding/contracting at different rates right where that flange is I have seen the repairs show through the paint after a short time. The proper way would be to take to a factory edge and replace at the adjoining panel OR **** weld the panels together and properly metal finish the area before beginning the paint substrate work. Also don't forget the back side of the repair will need corrosion protection so it is good to think ahead and plan out how this will be accomplished as you are working your way out of the repair.

Here are the **** clamps that were mentioned above.


And here they are in use. This was on my son's WJ panel replacement from a few months back.

 

[Walkers]

It used to be called hammer welding. Weld a few inches and then hammer and dolly the weld to remove the shrinkage.

 

[zmotorsports]

It used to be called hammer welding. Weld a few inches and then hammer and dolly the weld to remove the shrinkage.

Agreed. I think hammer welding and planishing terms are used interchangeably. I've heard it called both. Basically flattening out the weld and relieving the stresses from the heat due to the weld process.

 

[cannuck]

IIRD the OP does not have access to the backside to dolly the weld. Guessing that once he has tacked it, he is trying to make one continuous weld instead of stitching in widely spread out places. The key concept is to use as much heat as you can at the torch tip to move quickly with full penetration and limit time heat is expanding stuff, and make only very short stitches, never one beside the other. It is too tempting to a new TIG user to get the puddle just right and keep on going as it looks good through the lense.

 

[theoldwizard1]

The proper way would be to take to a factory edge and replace at the adjoining panel ...

BY FAR THE BEST SOLUTION !!