Bodywork

[RickL]

last one

last one. Any suggestions?

[RickL]

the whole story

This all started when I noticed that I had some warpage on the top of the cowl. I read about heat shrinking and tried to shrink the metal. That resulted in the damage in the first picture.

This happened on both sides of the cowl vent. I then tried to replace the sheet metal on the one side over the glove box and despite using short weld beads still got warpage and burn thorugh. I did practice on similar material prior to trying to install the patch. I did flange the patch to try to prevent the burn through but still got it.

That brings me to the state you see the in the pictures.

Suggestions?

Thanks,
Rick

[HWooldridge]

Rick,

Couple of questions:

What process did you use to weld it? Is it warped in the middle of the patch or off to one side? (I can't really see from the pics).

May have some suggestions based on your responses.

[RickL]

Weld

Mig weld .023 Co2\Argon mix. Warping is mostly at the back.

I will see if I can get a better picture of the warping I am looking at.

Rick

[tonkadoctor]

too much heat

Too much heat when you tried to shrink and then brazed. Still all is salvageable.

Heat shrinking is an art and is best for really small dents like hail damage and you really need a helper to quench it while it is hot, it takes a bit of practice to develope a feel for the speed and amount of heat to do it right.

Don't kick yourself, at least you have the guts to try something and ask questions.

I think you should purchase what is called a shrinking hammer, a pick hammer and a general purpose dolly for auto body work. It will allow you to shrink and shape the metal without heat. You don't need a set of really expensive hammers that I will be showing in the next few pics. You should be able to find a set that includes several usefull types of body hammers and a dolly at one of those flea market tool venders that would be fine for occasional use.

You can still braze that seam up but you will need as small of a tip as you can buy and get as thin a flux coated brazing rod as you can, go slow and tack it (about 1/4" tacks) about every inch quenching it as you go and build it up from there slowly , tack, quench, tack, quench.....grind down the braze and use the shrinking hammer and dolly (dolly goes on the oposite side of the metal when you are striking it with the hammer) go slow and work the metal back into shape from both sides.

shrinking hammer face

[tonkadoctor]

srhinking hammer 2

body

[tonkadoctor]

dolly

this is a heel type of dolly,my personnal favorite, you can use just about any heavy piece of metal like a 2# sledge if it will fit

[tonkadoctor]

pick hammer

this is a pick and finishing hammer used to get into tight places and finish shaping metal

[tonkadoctor]

sorry thought is was brazing

you have the right combo for mig (small wire and gas) but you can't usually run beads on thin sheet metal unless your tig welding.

to weld up the seam just squeeze the trigger for a second for a spot weld let it cool and repeat tacking it evey inch then work out the centers between the welds.

don't turn up the argon too high, it's as bad as not using enough argon because of the turbulance and impurities created by it. also make sure no draft, ventilation or fan is blowing the argon away while you are welding

[Bruce]

Grinding Time

Hey Rick,
What surface prep did you do before welding, have you tried to grind down any of your welds yet? Take care when grinding, or you'll get more heat/warping!

[RickL]

surface prep

The cab was sandblasted. I did not do any surface prep prior to this attempt at a repair.

What about the work hardening of the metal causing cracks?

What would be better MIG welding or brazing the seams? I have gas welding brazing equipment but the smallest tip for the Purox torch I have is a number 4


Rick

[tonkadoctor]

welding up the cracks

Mig would result in alot stronger weld. Brazing would lessen the chance of blowing away the edge of the metal. If you braze do not use anything bigger than a #00 or #000.

NOTE:
1. A #4 tip is waaaay too big for sheet metal work and is used for brazing 3/16" to 1/4" thick metal but read farther and I'll show you how it might actually work well.

2. if you braze, (really any welding) the metal needs to be as clean as possible, any rust, paint of oil will contaminate the braze and it won't stick well.

Get a piece of 1/4" steel (not galvanized) square stock (you can pick a small piece up at lowes or just about any hardware store for a couple of bucks) to shape and tack (just 2 tacks on each end to hold it while you weld up the outdside) to the inside of the seam. ( the better this piece fits the better the result, you may have to grind a bevel or radius in the edge that meets up with the crack to get it as tight as possible).

When welding concentrate the heat on the center of the seam so the 1/4" stock will absorb the majority of the heat

NOW IN ORDER TO USE THE #4 BRAZING TIP.....Heat the 1/4" stock from the inside staying away from the sheet metal as best as you can (it will get enough heat from conduction). Make sure the sheet metal stays flush with the 1/4" stock and apply the flux coated brazing rod from the outside, the heat when right will draw it in and cover both surfaces and will result in a nice strong seam with minimal grinding on the outside

[tonkadoctor]

welding

Best to you. Practice a little first with some scraps to get a feel for welding thick metal to thin

[HWooldridge]

I agree with the advice given but I am afraid that the brazing heat may cause more warpage. If it was mine, I would remove the patch and grind everything clean then start over with a piece that matched the contour. Try to get the fitup as close as possible. Spot weld it in as suggested above and just keep repeating that process until the seams fill, but alternate sides so the heat doesn't build up too much in one place. In other words, tack corner A, then corner C, followed by B and D. Then go right next to corner A and tack again, then B, etc., until the seam is closed.

[tonkadoctor]

Best would be TIG welded

If he could find someone with a TIG welder it would solve the whole problem, of the cracks anyways. I agree with you HW, it could possibly compound the problem and if he migs it still use the 1/4" steel backing to absorb the heat and alternate the tacks as you stated.

whatever you decide it has to be done slowly to prevent further damage.