MIG Welding

[smaclean]

Well,

We're almost at the point where we are ready to start cutting out the rust of our 64 Daytona and putting in new cancer free patches. Interior has been removed, dash removed,steering wheel our, and the left fender is off.

Removed the firewall liner last night and we found even more rust and even some dead mice.. Oh joy!!

We have some holes that need patching on the firewall where the drivers side door hinge is. I'm hoping this weekend I can remove the undercoating and start patching it.

So my question is that we have a MIG welder and I was wondering how to put the patches in. Should it be an overlapping weld with a 1/4 inch overlap or should we try doing a butt weld?

My bodyshop instructor thinks that we should be doing lap welds because they are so much easier.

My dad thinks we should be doing butt welds but he's never used a mig welder before. He did butt welding with gas the last time the 64 was restored and when he restored his 62 Champ.

Any opinions out there?

Thanks

Steve

[Alan]

The lap weld is better if you can get in from behind to put the patch in, if you can not get in from behind then the butt weld will give you less work to finish.

[Kdancy]

The butt weld will not leave an overlapping area for moisture and rust to start at.
Use .023 mig wire and 75-25 argon co2 gas mix, cut back the rusted area to no rust and with a flap disc or small die grinder disc clean up the welding line. Try to use the same guage material as the area you are welding and cut to leave a 1/16 to 1/8 space between old material and new patch, fill that with new weld. Don't get in a hurry and only do around a half to one inch at the time to prevent warping. Spot the whole panel in and then, taking your time, weld the whole panel moving around to do a short spot each time as you weld. If you have your welder set right so you don't burn thru and take your time, it will be a nice weld!

53commander HDTP
53 Champion HDTP
61 Cursed Purple Hawk
64 Champ long bed V8
64 GT

[smaclean]

quote:Originally posted by Kdancy

The butt weld will not leave an overlapping area for moisture and rust to start at.
Use .023 mig wire and 75-25 argon co2 gas mix, cut back the rusted area to no rust and with a flap disc or small die grinder disc clean up the welding line. Try to use the same guage material as the area you are welding and cut to leave a 1/16 to 1/8 space between old material and new patch, fill that with new weld. Don't get in a hurry and only do around a half to one inch at the time to prevent warping. Spot the whole panel in and then, taking your time, weld the whole panel moving around to do a short spot each time as you weld. If you have your welder set right so you don't burn thru and take your time, it will be a nice weld!

I guess I'd have to have the heat setting pretty low because when I was practicing the butt welds i was putting holes in the metal. Question I have how is the arc created when the wire is going across the gap? It's not touching any medal at that point? I'm assuming that you need to start on one side and move to the other side of the gap. Or do you just hold it in one spot?

Steve

[gordr]

Steve,

Once the arc is started, you can "carry" it with you a bit.

I used to do lap welds, but I now prefer to do butt welds; less grinding to finish them, usually.

You can get some nifty little clamps that hold the patch panel in perfect alignment to do a neat butt weld.

Another trick you should adopt is to get a small slab of copper or aluminum about 1/2" thick and the size of a credit card. Copper is preferable, but aluminum does work. Better yet, get an assortment of such pieces. Clamp one up behind the butt joint you are welding, and you can weld across it, and the weld won't stick to the non-ferrous metal. The thick slab also sinks the heat, and helps prevent heat distortion. You can weld over fairly large holes that way, too.

Invest in an automatic-darkening helmet; makes the job SO much easier.

Gord Richmond, within Weasel range of the Alberta Badlands

[Kdancy]

quote:Originally posted by smaclean

quote:Originally posted by Kdancy

The butt weld will not leave an overlapping area for moisture and rust to start at.
Use .023 mig wire and 75-25 argon co2 gas mix, cut back the rusted area to no rust and with a flap disc or small die grinder disc clean up the welding line. Try to use the same guage material as the area you are welding and cut to leave a 1/16 to 1/8 space between old material and new patch, fill that with new weld. Don't get in a hurry and only do around a half to one inch at the time to prevent warping. Spot the whole panel in and then, taking your time, weld the whole panel moving around to do a short spot each time as you weld. If you have your welder set right so you don't burn thru and take your time, it will be a nice weld!

I guess I'd have to have the heat setting pretty low because when I was practicing the butt welds i was putting holes in the metal. Question I have how is the arc created when the wire is going across the gap? It's not touching any medal at that point? I'm assuming that you need to start on one side and move to the other side of the gap. Or do you just hold it in one spot?

Steve

What size wire are you using? What heat range are you running? Even at a "just right" heat range and wire, you only weld a short run at a time or the panel will start burning thru and warping. Make sure you are not welding too "cold" as well, the weld ball will stick but not really penetrate the work. If you are a beginner, it is very important to have the weld line Clean, as that will help with the arc. Practice short "stitch" burst at first, pushing the weld puddle ahead of the gun. Gun technique is important in welding thin metal. You can do it, just practice!
Amen to the helmet Gordon mentioned. I would not be without one now.
I also use the little weld clamps --that helps hold the two panels in place and gives you the proper spacing at the same time.

53commander HDTP
53 Champion HDTP
61 Cursed Purple Hawk
64 Champ long bed V8
64 GT

[Mike Van Veghten]

Yea, pretty ugly. I have to do my Conestoga floors too. I bought full panel replacements...each side.

I plan to do the butt weld though, for the same reasons Kerry mentioned....future rust, why give it a good starting spot? It takes longer to prepair right, but it should be worth it....I hope!

Not looking foward to it. I'll start and finish one side then go to the other side.

[smaclean]

Even if a seam sealer is used to close up gaps in the seam it could still rust?

I have a Miller 135. Using 83% Argon 17% Carbon Dioxide with .23 sized wire. For lap welds i have the heat setting about 1/2 way.


Steve

[Mike Van Veghten]

You have two problems...

1. You'll have a hell of a time "FULLY" sealing all of the joints.
2. Even if you do get them all sealed at the edges or trying to "fill" them, there will be pockets of air everywhere that will contain and hold moisture.

Moisture + air = rust.

[Stude4x4]

I agree with the rest. A butt weld will be much cleaner if its just a hole on the firewall. Butt welds are not as strong but if that's not an issue, don't worry about it. Can't say about the auto darken helment, I'm still old fashioned with the flip down. But hey, if you're good enough you don't need a 150 dollar helmet. I don't think your wire size is .23, that's almost a 1/4 of an inch. When you get that big your talking stick welding. Its probably .023. What is halfway on your heat setting? Also if you really want the weld to look nice and not have to grind so much, then TIG weld it if you can. Much nicer and cleaner. Its more fun too.
-Jake

-Home of John Studebaker-

[smaclean]

quote:Originally posted by Stude4x4

I don't think your wire size is .23, that's almost a 1/4 of an inch. When you get that big your talking stick welding. Its probably .023



-Home of John Studebaker-

Yes it is .023 wire size. Missed the 0 when I was typing it. I'll look at the heat setting tonight and report back later.

Thanks to all

Steve

[Kdancy]

quote:Originally posted by Stude4x4

I agree with the rest. A butt weld will be much cleaner if its just a hole on the firewall. Butt welds are not as strong but if that's not an issue, don't worry about it. Can't say about the auto darken helment, I'm still old fashioned with the flip down. But hey, if you're good enough you don't need a 150 dollar helmet. I don't think your wire size is .23, that's almost a 1/4 of an inch. When you get that big your talking stick welding. Its probably .023. What is halfway on your heat setting? Also if you really want the weld to look nice and not have to grind so much, then TIG weld it if you can. Much nicer and cleaner. Its more fun too.
-Jake


-Home of John Studebaker-

It's pretty tough to tig weld old rusted metal, even after you cut back the metal needs to be really clean. Tig takes a lot more practice to learn well and the equipment cost more. For a beginner mig is the way to go. If done properly, strength won't be an issue and you'll have a very nice weld. As far as the setting on the machine, you just have to experiment as it has been my experience that all machines are a little different in how "hot" they weld. The settings are just a starting point. My machine (Lincoln 170) has a placard inside that tells you what heat and speed to use given the metal thickness and wire size. The miller may have this or it may be in the manual.


53commander HDTP
53 Champion HDTP
61 Cursed Purple Hawk
64 Champ long bed V8
64 GT

[rockne10]

For a beginner, I would suggest taking some of the scrap you've removed and practice on it first. Don't try to not burn through it; your arc may be too cold and not bond, in addition to wasting wire.

Find the point where it does just burn through and then drop a notch.
I agree with all previous advice to run short welds all around and return to fill in to prevent warpage; and the copper block suggestion will virtually eliminate waste and grinding the external side. Fairly sizable holes can be filled using that copper block.