Moving forward I've decided its time to patch some of these sports in the floor and trunk.

I'll be getting a Hobart Handler 140 and be starting with a couple of small projects around the house to learn to weld as I have zero experience. I plan to make a roller cart, a small welding table, and fix our mower dump cart that I busted last year. Who knew when it said maximum 500 pounds they actually meant don't put 700 pounds of rock and dirt in it

I've been doing research to get ready for this but I'm having trouble, even in welding forums, figuring out why MIG is so much better than Flux. I'm opting for a better welder so a tank is a bit out of the question moneywise at the moment unless I'm going to be totally screwed without and then I'll have to revisit that thought.

So my questions are as follows:

Why MIG over Flux, or is this not necessary for beginners?

General tips for a complete noob welder? I know this is normal and there are tons of tips, but I always like to hear stuff especially from people who just started themselves on whatever the question is.

When I get to patching the floors of my Mustang am I better off getting reman panels and cutting down to match what I cut out, or just using sheet metal to replace what I cut out? The patches I need to do aren't very large, 8"x8" is the largest I'll have to do, however one will have angle in the back seat floorboard where it angles up into the seat area.

 

Here is what I understand about the gas/flux-core issue, The gas won't really make "better welds", but it will be easier to get better welds that require less clean-up.

The flux core wire will leave "slag" on top of your welds that will need to be cleaned off in the finishing process, and/or if you intend to make another pass. You don't want to weld over slag. I have heard that the flux-core stuff will actually weld a little hotter than the gas, and it has it's place. If you are welding in the wind or even a breeze, flux core is your only option because the shielding gas will blow away.

I like welding with gas because I don't like cleaning off slag, especially from sheet metal, but trust me, flux core will work just fine so long as you clean it up.

 

I have worked in a fab shop that use a flux core wire at the same time as CO2 gas, it added heat and allows for welding oily or contaminated surfaces better.

MIG welders can use flux core wire and still be called a MIG welder, dont get to hung up on it.

I have used flux core wire on a floor repair in the past with success, but I prefer to use CO2 because its a cheap gas thats easy to get refilled or replaced. Keep in mind that beer taps and soda vending machines use CO2 to make bubbles and move the beverage through the system, so you can get a new tank in more places. I grew up in a bar and we always had a few extra tanks laying around and after learning that the O2 works better on a small welder than some of the more spendy versions it was a no-brainer for me.

If you are buying a new welder spend the few extra $$ and get one that works with gas, then you can go either way depending on what you are doing.

If you are building a weld table or fixing a yard car gas is just not needed, and with a good extension cord it is easier to move the welder to the work without dicking with that tank.

 

I like to use repair panels and cut the patch areas out of those. Practice on scrap for a while and learn your welder and what does what then decide on how detailed you want your floor work to get.

Some people like to lay a stop sign over the rust hole and screw/weld it/cover it in goo in and call it fixed, others like to trim the rust out, lay the patch panel down and leave a 1" overlap and weld it on both sides.

Some go as far to but weld the new patch in so it cannot trap moisture between those overlaps, I prefer that way. It is harder to do, just trimming takes patience and the welds take a bit more time to do and have them look good, but it is the only right way patch sheet metal, a floor is not any different than a hood or roof.
This is the point where someone will chime in that overlaps are fine and my car is not going to be in a show etc.. "Just a driver" they say, I wonder if those same people would wear patches on there cloths when they go out on Saturday night?

 

I'm doing our '65 coupe with ZERO welding experience. I also have a Hobart 140 MIG handler and it is a great welder and it will do what you ever ask it to to be done on a Mustang.
https://mustangforums.com/forum/clas...s-of-pics.html

I had a welder show me a few things and he had me practice on some scrap metal, but when welding on a car it is a whole other world.

You can practice all you want to, but you will find it is a whole other learning curve when welding your car. So you may as well just get to it after a little practice.

Old to new metal is one learning curve, new to to new another, old to old is another. Thick to thin metal is another, get the idea??? You will experience all these variables and then some when welding. You may as well just get to it after a little practice to see what it does.

Lynn

 

This is the point when someone chimes in over lap welds.

History has proven itself if the car is in the right conditions over the years factory lap welds are perfectly fine and have lasted 40+ years on these cars that probably have 2/3's of it's joints lap welded of some kind to hold them together.

History has also proven itself if you got leaks in places, bad seam sealer, then they could be a problem with moisture and rusting out, but these cars weren't sealed the best from the factory. We are building these cars and sealing these joints far better then the factory ever did and they "should be" better and hold up for our life time of usage.

I'm in the camp of if it is not seen easily and they have been properly welded and sealed they it will last longer then the factory lap welds will and should be of no problem.

Our car will not be a major show winning car, I don't want it to be, and it will be just a driver. So yes, lap welds are fine for our car if done nicely, sealed, dressed, and "hidden" properly.

BTW, I would go out with patches on my cloths on a Saturday night, but my wife wouldn't let me... LOL!!
Lynn

 

Lynbob, thanks for proving my point.

The word "hidden" just does not work for me.

 

I will chime in here since I am a fairly new welder. I bought a Hobart mig welder last summer and had absolutely no welding expierence. The reason I bought the welder was to replace quarter panels and floors on a 65 coupe. Although my Mig welder will run with gas or just flux core I chose to do the flux core to cut cost and because of the little use I planned for the welder after my project was finished. However with that being said if I could go back I would have used the gas. My reasoning was due to how hot flux core is. Even at the welders lowest setting I burned through the thin sheet metal in several places. No matter what I did, varying speed, technique, etc. it always wanted to burn through. This made it very tough. Now on thicker metal I think the flux core would be great but if I ever had to do sheetmetal again I would definitely use gas.

 

One size seldom fits all,,,, at least well...

Generally we butt weld just about everything, if a patch is going on a floor, butt welding is better, but it IS NOT always the best choice. (i.e. If a whole floor, or a large section of floor is going in, and it was originally installed with a lap weld, then we usually put it back with a lap weld.)

If a customer wants me to patch a hole in the floor on a car that is otherwise a POS, I might not take the time to butt weld a patch in. Sometimes it ain't worth the time a butt weld takes.

If a person avoids lap welding any panel that sees daylight, (shiny paint) there aren't going to have much of a problem so long as it is it is done well.

 

Using the mig process, we never weld sheetmetal, we either spot it in, or use very short stitch welds. (joined together to form a solid weld if desired). Unless a person wants to fix a bunch of distortion, and fill a bunch of burn throughs, migs are for spotting and stitching.

the TIG process is better suited for more or less continuous welds on sheetmetal....