Welding Roof & Warping

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JackCisco

Member
72
29
18
UK
Hi,

I'm not really sure where to post this, but maybe this will be a good place as people will know the car and some knowledgeable welders will pop up.

I have a welder who's patching rust for me on my 85 Town Car. There's about 7 holes in the roof underneath the vinyl he's currently working on. He's done 3 so far and the roof is warping quite bad.

I'm no welder, but I understand if you put too much heat into the large piece of sheet metal of a roof and it cools unevenly then it will warp.

I've heard of a method called stitch welding which is used for scenarios like this to avoid too much heat, along with an air gun.

I don't think he's using this stitch welding method judging by the look of the weld and the speed at which he does it, but he is using an air gun.

My question is:
Should he be able to prevent warping this roof? Is it easy/hard to do?
Should I be looking for another welder?
 

jkeaton

Well-known member
1,919
932
113
Winston Salem, NC
Hi,

I'm not really sure where to post this, but maybe this will be a good place as people will know the car and some knowledgeable welders will pop up.

I have a welder who's patching rust for me on my 85 Town Car. There's about 7 holes in the roof underneath the vinyl he's currently working on. He's done 3 so far and the roof is warping quite bad.

I'm no welder, but I understand if you put too much heat into the large piece of sheet metal of a roof and it cools unevenly then it will warp.

I've heard of a method called stitch welding which is used for scenarios like this to avoid too much heat, along with an air gun.

I don't think he's using this stitch welding method judging by the look of the weld and the speed at which he does it, but he is using an air gun.

My question is:
Should he be able to prevent warping this roof? Is it easy/hard to do?
Should I be looking for another welder?

If he's a good welder, yes he should be able to prevent warping.
Yes, you should if he's not a good welder.
 

Hound Dog

Active member
129
79
28
I am a terrible welder. I know this though so at least I have that going for me.

I do know it does need to be stitch welded. If it is warping, the stitches need to be further apart and he needs to go slower so the metal does not get to hot.

I would suggest another welder. One who does body repair regularly. Don't let a guy like me weld it.
______________________________
 

JackCisco

Member
72
29
18
UK
Thanks for the input so far everyone.

I went and spoke to him today and explained I wasn't happy with it. He had indeed been welding about half an inch seam at a time and cooling it off.

I explained to him what I thought he would have done and his response was as follows:
He's adamant that doing it the way I suggested wouldn't make a difference.
He's going to do it the way I suggested on the other half of the roof and send me pictures later to show that.
He said the reason this happens is because of the gap between the new metal and the roof pulling everything in as the weld cools.
You can't have the new metal butting up against the old with no gap otherwise the weld won't penetrate all the way through.

I've attached pictures I took today of the work, I don't know if anyone will be able to tell anything from this or if it will show the extent of the distortion.

Would some sort of brace welded to the other side of the roof help?

Any further opinions are greatly appreciated!
 

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Ballyhoo

Active member
160
77
28
The welds themselves aren't to bad, easily hit with a grinder. Which needs to happen irregardless. Being a roof panel, hammer and dolly work can smooth those patch areas nicely for the finish filler. I've seen much worse. You have to remember, small patches/thin metal. Even working clockwise, a tack at each corner then the center between each and so forth until fully welded you're bound to have some distortion.
 

07-TC-SL

Member
58
38
18
I own a welder and have done just a bit of sheet metal automotive welding. Your current welder is welding too much at one time, as others have said. It should only be single tack welds, jumping around to different spots for each weld. He just isn't experienced enough with auto body welding obviously. Your roof warping is the worst I've ever seen.
 

JackCisco

Member
72
29
18
UK
Thanks for the input guys.

The odd thing is that he's been fabricating and welding for if I'm correct 10+ years, a lot of which has been on vehicles. I know this from people who have known him for longer.

He is always rammed for work and I've seen some of the repairs to nasty door sills and arches etc that all looked good.

I've never seen him do anything on a big piece of thin sheet metal though.
Although I've seen some metal boats he's made from scratch of which the welds were extremely neat and I don't remember any significant warping.. perhaps because the metal was thicker.

I've attached images of some different work he's done since yesterday. I've not seen the finished piece in person this time but it looks ok from the after picture he sent me?
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Jaskim06

Active member
287
164
43
Hi,

I'm not really sure where to post this, but maybe this will be a good place as people will know the car and some knowledgeable welders will pop up.

I have a welder who's patching rust for me on my 85 Town Car. There's about 7 holes in the roof underneath the vinyl he's currently working on. He's done 3 so far and the roof is warping quite bad.

I'm no welder, but I understand if you put too much heat into the large piece of sheet metal of a roof and it cools unevenly then it will warp.

I've heard of a method called stitch welding which is used for scenarios like this to avoid too much heat, along with an air gun.

I don't think he's using this stitch welding method judging by the look of the weld and the speed at which he does it, but he is using an air gun.

My question is:
Should he be able to prevent warping this roof? Is it easy/hard to do?
Should I be looking for another welder?
It's hard to do without any warpage at all. But he can slow down and weld for just a second or so at a time and move around. Do 1 lil weld then move to another different patch spot and just keep playing musical welds all over.

Also he can use brass under welds so the brass will soak up alot of the heat instead of the roof metal. I did this on a 72 bug. I didn't want the molding going down both sides under the crease. So I held brass stick against the holes while my father tacked them. And no warping. And that's very thin metal. The bigger the brass the more heat it will soak. But he needs to just tack and move. Alot of welders who do welding on pipeline, construction etc is welding very thick steel and very good at it, compared to a 18 gage roof panel. Same welding but way different technique and process. Slow and steady wins the race here. I've seen ppl warp auto panels go hell and back welding but mostly sandblasting. They get done and looks good straight on, look down side looks like a washboard. Bad juju.
 

Jaskim06

Active member
287
164
43
It's hard to do without any warpage at all. But he can slow down and weld for just a second or so at a time and move around. Do 1 lil weld then move to another different patch spot and just keep playing musical welds all over.

Also he can use brass under welds so the brass will soak up alot of the heat instead of the roof metal. I did this on a 72 bug. I didn't want the molding going down both sides under the crease. So I held brass stick against the holes while my father tacked them. And no warping. And that's very thin metal. The bigger the brass the more heat it will soak. But he needs to just tack and move. Alot of welders who do welding on pipeline, construction etc is welding very thick steel and very good at it, compared to a 18 gage roof panel. Same welding but way different technique and process. Slow and steady wins the race here. I've seen ppl warp auto panels go hell and back welding but mostly sandblasting. They get done and looks good straight on, look down side looks like a washboard. Bad juju.
Holy shit. I just looked at pics. WOW. Welding in a doorsill with a few pieces or layers of metal making up the jam is a lil bit easier than a 5ft by 5ft 18 gage sheet stretched out on 4 corners. He can try a rosebud, propane weed burner etc, something that puts out a good deal of heat in a large area and get the lows hot and quench with a rag ot towel Soaked in cold water. The hot/cold change that happens in milliseconds will make it tight and pop back into place. Done this with dents and roofs before. It's like putting a ring gear in oven to heat up to expand it so you can install. Heat expands, cold shrinks. They have shrinking disks too for grinders but that's a big area for that. Idk just my thoughts. Or get back to best as you can and use resin to fill lows or put a vinyl top on and cover up. Looks like good welds, just got too hot. Welding a large, thin and unsupported area is hard. Talk to some old welders. My father showed me the brass, copper trick and the heat and water trick for lows. Good luck. When you do very thin metal settings need to be way way down, wire speed and heat. Should sound like bacon cooking in a cast iron skillet, keep it wet with cold water, ice mixed in etc. Now it's going all in the roof. With copper or brass under it will soak alot of that heat up. And not go through stretching the roof.
 

JackCisco

Member
72
29
18
UK
Thanks everyone for the input.

I've given images to 2 other welders and am waiting to hear back. Unfortunately this kind of work is a dying art in the UK so it's hard to find people up to the task.

I've spoken further to the welder and asked him to do as follows when finishing the rest of the approx 7 holes:
Prep each hole with the new metal tacked in place
Put one tack on each hole
Blow it off with compressed air to cool it
Continue again 1 tack at opposite side on each hole
Blow it off again

This way he should be able to get through the job of welding the roof up at a reasonable pace without putting too much heat it, instead of doing one hole at a time.

He said he's happy to do it like that for me.

I'm not too sure how he'd get a chunk of copper fixed to the bottom to soak up heat, unless he had the other welder there hold it for him.


I've told other's what I suggested, and some thought the welds would crack as it wouldn't be a complete weld. That didn't make sense to me though.

When you stitch weld like this every tack half overlaps the previous. With a suitable gap between the new and old metal and the right settings there should be a little dimple in the tack too which indicates the filler metal penetrating all the way through.
Am I making sense? I've literally welded practice pieces together like this, although not giant pieces like the roof, it worked?
 
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07-TC-SL

Member
58
38
18
I'm surprised your welder is so agreeable to doing it your way instead of his way. He can't be that bad of a guy :)
______________________________
 

Jaskim06

Active member
287
164
43
Thanks everyone for the input.

I've given images to 2 other welders and am waiting to hear back. Unfortunately this kind of work is a dying art in the UK so it's hard to find people up to the task.

I've spoken further to the welder and asked him to do as follows when finishing the rest of the approx 7 holes:
Prep each hole with the new metal tacked in place
Put one tack on each hole
Blow it off with compressed air to cool it
Continue again 1 tack at opposite side on each hole
Blow it off again

This way he should be able to get through the job of welding the roof up at a reasonable pace without putting too much heat it, instead of doing one hole at a time.

He said he's happy to do it like that for me.

I'm not too sure how he'd get a chunk of copper fixed to the bottom to soak up heat, unless he had the other welder there hold it for him.


I've told other's what I suggested, and some thought the welds would crack as it wouldn't be a complete weld. That didn't make sense to me though.

When you stitch weld like this every tack half overlaps the previous. With a suitable gap between the new and old metal and the right settings there should be a little dimple in the tack too which indicates the filler metal penetrating all the way through.
Am I making sense? I've literally welded practice pieces together like this, although not giant pieces like the roof, it worked?
Take the right piece of copper or brass is what I used, and make is so it has 2 legs with magnets so he can place it on the hole and magnets will afix to the roof. Like a stinger ground on the pipeline. Idk if your familiar with that or not. You only need a piece of brass about 2 inches round or so and same long. Drill a couple holes for self tapping screws and use a welding rod for legs. Epoxy a few good strong magnets and you can set it where you like and weld away. I wish I could draw you a picture. I may do that so you can see what I mean. But use your imagination and just make it so it will stick to steel and have the brass in middle. Blowing with air will work but it's not the best way. Ice water and something to soak the heat so it goes into the weld and soft metal and its not in the rest of the panel. If he's done auto body fab before he should know this trick. It's been around for a long time. Called a heat sink. There's a putty type stuff called heat freeze heat sink. Looks like silly putty. I've never used but it's cheap and easy to use by looking at it online. In video it's being used on a VW door.
 

JackCisco

Member
72
29
18
UK
So the welder finished a few weeks ago. He did the rest of the roof how I asked and it doesn't look any worse.

To be fair the rest of his work looks fine. He was more than happy to send me lots of pictures of it all too. Unfortunately they don't all quite show the process from before to after.

I've attached a few.

Also, what's with the damn bags with foam in them? Everywhere there was a significant amount of rust, for example the door pillars behind it was one of these bags soaking with moisture!
 

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Jaskim06

Active member
287
164
43
The bags of foam, I believe, are for sound deadening.
Correct. Used this for its cheap price compared to, idk how about rubber with holes so it don't hold water and rust Ford? Come on. Ford charged between 40-50 Grand for these cars. Mine did same thing. A popular one is around the gas filler assembly. I first thought previous owner did some driveway fixing. It could even be a small piece of rubber so it don't rattle. It holds all the mud, dirt, water, and salt if driven in cold climates. I'd rather hear the rattle and fix it then have this idea. But the engineers didn't have to work on them or fix them.
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07-TC-SL

Member
58
38
18
I'll let you in on an industry secret. Ford and others do not care in the slightest about long term longevity. 10 years and send it to the junkyard. Rust, not on their radar unless it rusts inside the warranty period.
 

Jaskim06

Active member
287
164
43
I'll let you in on an industry secret. Ford and others do not care in the slightest about long term longevity. 10 years and send it to the junkyard. Rust, not on their radar unless it rusts inside the warranty period.
New ones are. Recall on new trucks and bad rusting. Idk how Toyota can have a carry or corolla dipped in zinc and no rust for 20-30 years and they cost what 12k or more new, but our cars cost 3 3 or more times that much and it's whatever. If you want repeat customers you take care of them and sell them a well built automobile and they'll keep paying 50k for your new model every few years or so. All it takes is that dip in the zinc primer tank and it'll last forever unless the coating is chipped or busted to let rust, water and nature take over. New trucks cost almost as much as a very nice car or 2, shouldn't be rusting in a few months. We all took a hit in 2020 but don't mean we skimp on stuff like that or safety. Just make a few more items out of old water and milk jugs and keep it rust free for a few years.
 
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