Spot Welding vs Mig Welds - Chevelle Tech
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post #1 of 18 (permalink) Old Apr 1st, 20, 7:46 PM Thread Starter
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Spot Welding vs Mig Welds

I'm considering doing spot welds for as much as I can on my 67 malibu.

I have to replace dang near every panel and all the floors because of rust (car sat out in the elements for many years).

Anyone have experience using a spot welding machine for panel/floor replacement? Recommend it over drilling and mig welding? Maybe a combination of both?

Is there a resource for the specific locations for each spot weld and how many at each location?
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post #2 of 18 (permalink) Old Apr 1st, 20, 8:12 PM
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Re: Spot Welding vs Mig Welds

Wherever you ca use a spot welder go for it. From my experience it seems like every place I wanted to us it I couldnít get the jaws in place. I did use one 25 years ago at a trade school that had a separate handle where you could put it damn near anywhere but havenít seen one since. Maybe they still make them, not sure.
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Tighten it till it strips and back it off a quarter turn.
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post #3 of 18 (permalink) Old Apr 1st, 20, 10:39 PM
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Re: Spot Welding vs Mig Welds

I just replaced full quarters, one firewall cowl side, the tail light panel and the panel in front of the trunk lid and I used a handheld 220 volt spot welder everywhere that I could.
It saved me from so much grinding after all the plug welds that I would have had to do.
I had to modify the tips to fit into where the gasket goes around the trunk opening so that it didn't touch the gutters.
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post #4 of 18 (permalink) Old Apr 2nd, 20, 1:33 AM
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Re: Spot Welding vs Mig Welds

Hi
spot weld as per factory at least look better . As people have mentioned far less finishing work . Doing to factory standard will at least give u factory strength . Remember either done poorly the welds will pop and can cause panel movement /clicking noise .
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post #5 of 18 (permalink) Old Apr 2nd, 20, 1:57 AM
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Re: Spot Welding vs Mig Welds

Quote:
Originally Posted by danbo View Post
I just replaced full quarters, one firewall cowl side, the tail light panel and the panel in front of the trunk lid and I used a handheld 220 volt spot welder everywhere that I could.
It saved me from so much grinding after all the plug welds that I would have had to do.
I had to modify the tips to fit into where the gasket goes around the trunk opening so that it didn't touch the gutters.
Dan, are those AMD panels? I just replaced the same on a coupe and have the identical deck lid to quarter gaps at the light pocket, had to slit the last 5'' of the quarter a tinch, both sides. lol
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post #6 of 18 (permalink) Old Apr 2nd, 20, 5:18 AM Thread Starter
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Re: Spot Welding vs Mig Welds

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Originally Posted by danbo View Post
I just replaced full quarters, one firewall cowl side, the tail light panel and the panel in front of the trunk lid and I used a handheld 220 volt spot welder everywhere that I could.
It saved me from so much grinding after all the plug welds that I would have had to do.
I had to modify the tips to fit into where the gasket goes around the trunk opening so that it didn't touch the gutters.
Where did you purchase your large jaw spot welder from?
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post #7 of 18 (permalink) Old Apr 2nd, 20, 8:29 AM
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Re: Spot Welding vs Mig Welds

Perhaps Iím missing your thought processes but spot welds canít be used to replace mig welds where needed. Mig welds can be used in place of spot welds.

If you are going to dissect your body down to the level of the base panels where they can be welded like factory, then spot welding is a no-brainer if you have the equipment. If you are doing body shop level patch repair, spot welding wonít get you all the way there.

I think most of us would prefer to have an OE panel replacement with spot welds. Itís just not practical in most cases.

I donít like being manipulated!
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post #8 of 18 (permalink) Old Apr 2nd, 20, 8:44 AM Thread Starter
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Re: Spot Welding vs Mig Welds

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Originally Posted by Alan F View Post
Perhaps Iím missing your thought processes but spot welds canít be used to replace mig welds where needed. Mig welds can be used in place of spot welds.

If you are going to dissect your body down to the level of the base panels where they can be welded like factory, then spot welding is a no-brainer if you have the equipment. If you are doing body shop level patch repair, spot welding wonít get you all the way there.

I think most of us would prefer to have an OE panel replacement with spot welds. Itís just not practical in most cases.
The idea/plan was to use spot welding where I can (a number of places I know I won't be able to such as trunk pan to floor pan). It's not my intention to replace mig welds, but use spot welds where I can, and the remaining where I don't have access to drill and mig.

If there is a larger jaw spot welder, I'd like to know if any have one/used one, and any brands to buy/stay away from.
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post #9 of 18 (permalink) Old Apr 2nd, 20, 12:21 PM
 
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Re: Spot Welding vs Mig Welds

Use a jaw-less spot welder made for body work. I just sold a older one for $200 They are out there. Body shops rarely use them. That is where I found the one I sold.

https://www.ebay.com/itm/Autobody-Du...UAAOSwovldjCqm
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post #10 of 18 (permalink) Old Apr 2nd, 20, 2:20 PM
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Re: Spot Welding vs Mig Welds

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Originally Posted by John Moore View Post
Use a jaw-less spot welder made for body work. I just sold a older one for $200 They are out there. Body shops rarely use them. That is where I found the one I sold.

https://www.ebay.com/itm/Autobody-Du...UAAOSwovldjCqm
That is similar to what I used 25 years ago.

Tighten it till it strips and back it off a quarter turn.
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post #11 of 18 (permalink) Old Apr 2nd, 20, 5:37 PM
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Re: Spot Welding vs Mig Welds

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Originally Posted by slowmo55ss View Post
Dan, are those AMD panels? I just replaced the same on a coupe and have the identical deck lid to quarter gaps at the light pocket, had to slit the last 5'' of the quarter a tinch, both sides. lol
Yes AMD. I had one before this that was labeled CHL Auto Parts and that one was awful! It did not fit at all.
This AMD one was a huge improvement.
Nobody wants to hear this but, the spot welder I used was from Harbor Freight.
I used the 220 volt one and it has worked very well. I have lent it to a friend that put new rockers on his pickup and he had no problems at all with it. (This guy is a welder / Fabricator by trade).
I did many test welds on different pieces of sheet metal with and without weld through primer and the welds were stronger than the surrounding metal.
I used the mig welder to plug weld where I could not reach with the spot welder and on my quarters I used Panel Bond on the lower section (below the quarter window) and around the rear wheel opening and at the bottoms of the trunk drop offs.
The spot welder comes with one set of jaws with about 8" of throat, but I think that you could make custom jaws out of copper grounding rods.
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post #12 of 18 (permalink) Old Apr 2nd, 20, 7:17 PM
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Re: Spot Welding vs Mig Welds

Quote:
Originally Posted by danbo View Post
Yes AMD. I had one before this that was labeled CHL Auto Parts and that one was awful! It did not fit at all.
This AMD one was a huge improvement.
Nobody wants to hear this but, the spot welder I used was from Harbor Freight.
I used the 220 volt one and it has worked very well. I have lent it to a friend that put new rockers on his pickup and he had no problems at all with it. (This guy is a welder / Fabricator by trade).
I did many test welds on different pieces of sheet metal with and without weld through primer and the welds were stronger than the surrounding metal.
I used the mig welder to plug weld where I could not reach with the spot welder and on my quarters I used Panel Bond on the lower section (below the quarter window) and around the rear wheel opening and at the bottoms of the trunk drop offs.
The spot welder comes with one set of jaws with about 8" of throat, but I think that you could make custom jaws out of copper grounding rods.
This is interesting, as i am trying to do this very thing. I bought a grounding rod to try this, but have not gotten to it yet. I was going to try and heat the rod end up and bend it in the vice. I wonder if it will bend like i want or will it just break. I guess i will have to just try it. Terry
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post #13 of 18 (permalink) Old Apr 2nd, 20, 8:09 PM
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Re: Spot Welding vs Mig Welds

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Originally Posted by 68-13427 View Post
This is interesting, as i am trying to do this very thing. I bought a grounding rod to try this, but have not gotten to it yet. I was going to try and heat the rod end up and bend it in the vice. I wonder if it will bend like i want or will it just break. I guess i will have to just try it. Terry
I'd like to see how you make out with this.
The biggest things about this welder is to keep the tips clean and sharp and to clean where the copper jaws fit into the welder itself so that they make a good electrical connection.
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post #14 of 18 (permalink) Old Apr 2nd, 20, 8:47 PM Thread Starter
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Re: Spot Welding vs Mig Welds

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Originally Posted by danbo View Post
I'd like to see how you make out with this.
The biggest things about this welder is to keep the tips clean and sharp and to clean where the copper jaws fit into the welder itself so that they make a good electrical connection.
Sharp as in flat, and clean surface I assume?
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post #15 of 18 (permalink) Old Apr 3rd, 20, 8:22 AM
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Re: Spot Welding vs Mig Welds

Sharp as in pointed like a pencil.
I used scotch brite to clean the end of the jaw that goes into the welder and to clean the brass blocks where the jaw gets clamped into the welder.
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