Butt Welding ?

rustover

Member
Tonight I butt welded a patch in my 72 Camaro. I had the welder set just a little hotter than the chart and I backed the underside up with a copper plate. I did burn through in one spot but it filled in nice. I just tacked it in and kept tacking around until I had it filled in. My question is on the underside of the weld. Its a hard area to access, and I'm wondering if it looks acceptable to some of you more experienced welders. There are a couple of spots that I think I can see the original seam, but its hard to tell. Here are a few pics.





I think I need to work on my consistently on how long I keep the trigger pulled.

Here is a few pics of the top side.







I did re-weld the first part of the patch from the backside, inside the car. That's why the haz area is greater in the front.

Here is a pic of the inside where I re-welded it.



My plan is to continue to grind the top, I have one of those small belt sanders that I was going to run over the backside ( The first two pics), then coat the backside in epoxy, then smear some fiberglass filler over it. Wanted to run it by you guys first to see if you thought I was ok to proceed?

Thanks for the help,

Russ
 
Went back out to the garage and turned the lights off, used a flashlight and inspection mirror and there are some areas that I can see the original seam. So now I guess I need to figure out how to fix it, I'm thinking I will grind the top down, scribe a line on the original seam and try to re-weld it hotter.
 
Russ, Panel fitment looks excellent, weld "dots" here and on the underside look like you have good weld penetration...







I think your lack of weld penetration in certain areas can be answered here.....






I would suggest to planish and grind down the weld dots in between "tacking sessions" to get the weld dots back down to about panel thickness. If planishing is not accessible, at least grind down some of the weld proud. All that buildup is acting as a heat sink and preventing adequate weld penetration..... By leaving the welds there you are basically increasing panel thickness by about 3 to 5x. Subsequent welds are now too cold for that amount of material.
 
Thanks for the reply Robert and yes that makes a lot of sense. I was reading your build thread last night about planishing and I never thought about grinding as I go. I will definitely go this route next time. What do you think is the proper way to proceed from here? Do you think if I grind down the weld to flush panel thickness, will I be able to re-weld it and get good penetration through the existing weld that is left on the top? Thanks for the help.
 
Granted it will be easier to weld from the top, so you'll have to grind away the excess weld there and give it a go. Should work just fine..
 
Thanks Robert, I will start re-working it tonight. I'm going to get me some scrap and dial in the welder a little better. I let you know how it goes. Thanks again. Russ


MP&C;n72659 said:
Granted it will be easier to weld from the top, so you'll have to grind away the excess weld there and give it a go. Should work just fine..
 
Wanted to post some more pics. I scribed me a line on the top side of the repair and re-welded it tonight. I just barely turned the heat up just a little and it did great. Took my time and ground down the tacks as I went. Also when I first welded it I backed it up with a copper plate. This time I didn't use the copper plate. Overall not too bad. I'm still learning, Got a long way to go. Just wanted to say thanks Robert.











Next I'm trying to figure out the best method to address the underside of the weld. I ground down what I could reach with a mini belt sander. I still left some of the weld proud in fear of taking too much material away from the sides of the weld. I'm thinking epoxy first, then not sure if I should use filler and more epoxy or epoxy followed by seam sealer.
 
We were doing some of the same stuff today, and had some clearance challenges with grinding the bottom side of the welds...


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It gets a little tight from the bottom side.


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We were using a straight die grinder and 3" cut off wheel and found it hitting the sides before the weld. So we changed to a right angle die grinder so your hand doesn't block you view, and I typically keep some half-used cut off wheels for tight spots like this. Worked like a charm..


Your repair looks nice, has good consistency..
 
Thanks Robert, I have been saving some of those half used disc for the same things. I starting welding in the trunk pan this week. It went pretty good. I did have the welder set up high to get good penetration into the frame rails and inner structure. The pan is 20ga and the rails are 18, I had the welder setup for 16. I do have the passenger side rail giving me some trouble. I had to use clamps and screws to pull the pan to the rails. I'm not sure if it was the clamping or welding or both, but I created a small valley over the frame rails. I haven't finished grinding out all the pan yet, but I think the other side is ok. The pics make it look a lot bigger but the valley is about 1/16 inch deep. I have thought about it, and I'm not sure if this can be fixed other than a skim coat of filler, due the valley being over the rails underneath. Just wanted to ask you your thoughts about this. Thanks, Russ









 
If the welder is set for a perfect "dot" across the gap and connecting the 2 panels, then it is to cold to weld thru 2 "dots" and 2 panels. Grind the dots down before the next set of "dots" and you will get better results as you will be welding material of about equal thickness instead of twice + as thick by not grinding.
 
When butt welding sheet metal and using the connect the dots method, what is the correct distance for the gap being welded together using .023 wire. Those little clamps that hold the sheet metal seam level and together are .050 and that seems a little wide to me. I'm thinking more like a .023 gap for .023 wire?
 
Outlaw I think those clamp gaps are wide myself. I think the size wire like you said plays an important role. With that being said I have been able to jump gaps larger than those clamps by starting on one side and welding to the puddle as I jump the gap with .023 wire. I don't like to do this because it takes longer and you induce more heat in the metal. This makes panel fitment key. On wider gaps the .030 wire might work better but I'm not sure, I've always used the .023.
 
They are actually listed at .040 but my guage shows them closer to .050. If it was just a short weld I would not be as concerned. This is about six feet of weld across a flat panel so I have no room for error. Fittment is going to be a real challenge for me so I might as well close the gap as much as I can. I can get c clamps or vice grips to hold the seam together before I spot it. I would use the .040 clamps on something like 1/8 metal myself.
 
You can use a small shrinking disc and bring those low spots back up.
 
I always butt weld panels any time I can, the final results are always so much better, getting to the back side to be able to plannish the weld seems to be the key to me, You have to be able to stretch that weld back out a little to get rid of the warpage, I've took off full quarter panels before just to be able to plannish all of the welds from repair work..You can't always do that but in some cases when there is a lot of welding it's worth the extra effort.
 
I ran into one of the welders on this project and he said they couldn't remove the panels to plannish the welds due to the nature of the build, so they used a stud welder to stretch the weld out, then shrink the high spots. It was shortened, sectioned, and the width was reduced.


59%20imperial-speedster%20section_zpslm5oo3lt.jpg



These guys donated their evenings and weekends for 3 1/2 years to get it all done except paint, chrome, and upholstery, at the owners home in a two car garage.


1959-chrysler-imperial-speedster_zps3061wsfh.jpg





If anyone is interested, you can see it all here

http://www.hotrod.com/cars/featured/hrdp-1107-1959-chrysler-imperial-speedster/

And the design here

https://murraypfaff.wordpress.com/
 
Chad.S;n77880 said:
I always butt weld panels any time I can, the final results are always so much better, getting to the back side to be able to plannish the weld seems to be the key to me, You have to be able to stretch that weld back out a little to get rid of the warpage, I've took off full quarter panels before just to be able to plannish all of the welds from repair work..You can't always do that but in some cases when there is a lot of welding it's worth the extra effort.


Chad, do you planish each spot after you spot it or do you planish the seam after its closed? My understanding of planishing is to hammer it immediately after the weld is applied. That would mean hamering each spot immediately after its welded. Thats a lot of stopping and starting on a long seam. Spot, stop, hammer, weld, stop, hammer and keep going until you connect the dots?
 
Rustover, you got some pretty nice welding going on there. Can you tell me a little about the "mini belt sander" you make reference to? I have looked at the 3M version and the fein model. They are both pretty expensive but look like they do awesome work.
 
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