I have 2 small areas of rust on the floor of my '49 Chevy, neither one will be bigger than 12"x 12" after trimming out. I won't need the whole patch panel. 2 questions - 1 - Cut the hole in the floorboard first, then trim the patch to fit? (this makes sense to me) 2- My gas welding skills are minimal; should I practice, practice, practice or go for a small MIG/TIG unit? (I really don't know the difference between the 2). If I go for MIG/TIG note that funds are, well, tight.....
Rust holes have a way of getting bigger, the more you look. So yeah, cut out the rust and get to solid metal all around before you trim the patch to fit. Gas welding sheet metal is fun, you can "hammer weld" it and not much finishing is needed. But it takes some practice, and you'll find that things move around a lot from the heat, so expect to need to do some shrinking/stretching work to get it flat again and not "oil can" after you're done. Practice will help....but eventually you need to get in there and do it, and you'll find a bunch of new things you'll learn, the hard way. That's how it works. MIG is "wire feed" arc welding. The wire feeds into the weld, as well as being the source of the arc. . TIG is sort of like an electric arc torch. You use the arc to heat the metal, and you add filler rod as needed, like when using an oxyacetylene gas torch. MIG is an easy process to learn, although it can be tricky getting good at it, there are a lot of ways to do it wrong. There is also "gasless" MIG, which is done with flux core wire, and leaves a mess. It's cheap to get into.
I'd suggest gas welding it. For one thing, its a floor pan, so its a good chance to practice on some welds that are going to be hidden anyway. Practice a bit first, SMALL tip, go slow, move around alot, Spend most of your time fitting the panel VEEEERY carefully, minimal filler rod, light/minimal hammer and dolly work as you go. You will want a helper to hold the dolly in place on the backside, as its a floorpan.
Thanks guys - looks like I'll go with gas, smallest tip I have is a #1 'Hammer weld' Is that done 'cold' after welding? It will be easy to to hold the dolly by myself, the rust is near the door sill (right along side the front seat) in the middle of the door opening.
Hammer welding...right after you weld a section, you set the torch on a stand and immediately back the weld with the dolly, and hammer it with a body hammer. Look on youtube, you might be able to find an instructional video or two.
given your limited knowledge of welding I"m going to do the taboo here and suggest you think about putting the patch panels in with panel adhesive. Lord Fusor or the the like. these new products are used regularly in late model crash repair and are strong as crap, but generally frowned up in the restoration/hot rod world.
If the welding doesn't work out (and I don't set the car on fire....) I might give the adhesive a try, but I really like learning new stuff
if I walked into any body shop using the stuff id walk right back out I know we never used it 10 years ago. id go with mig(that's standard wire with argon/co2 mix) and do small beads since its a floor and a little warping will not matter much
I'd mig it too, but if I didn't have the skill set to do it right that's a viable option. like I said, it's really a taboo thing. i've seen it on here a few time but it was used along with welding. it was just some food for thought.
Want to know the secret to a perfect fit up weld joint? Well first you do need to cut out the rust and get to good metal. that can be a rough cut to the small side as "within 1/2 " of where youd like your weld joint. now trim your patch down to within 1/2" bigger of where you'd like your weld joint. Fit it nicely and as pretty as you like and use self tapper sheet metal screws to hold it in place within the 1" over lap. Now cut threw both pieces a few inches at a time with a thin kerf blade. Tack as you go. As you reach the screws remove them and tack. I usually screw about every 4-6 inches. Cutting threw both panels at the same ensures you of a perfectly fit joint no matter how irregular you cut it. Welding/ tacking will be much easier with some backing. You can use aluminum, copper, or cast iron. Them cheap ass harbor freight body dollies are good for something
I agree!! If the OP never welded and these patches will get him closer to the road then this option is wise, Considering the cost of welding equipment and the learning curve. Learning to weld and starting on sheet metal can be very frustrating to a beginner. Where in Pa. do you live? I,m in southern Chester County,Is the car drivable? Come on down and use my welding equipment and maybe you will get hooked on metal work with out spending any start up money. I graduated with a Dave Downs way back in 1972,Is this you? Pete
make sure the undercoating is cleaned off at least 2" from the weld joint. and keep a water hose with a spray nozzle handy for fires.
Well, did a little research on panel bonding and just as I suspected the adhesive is a methacrylate . I have used similar in my work in the composite industry. Will it work ...oh yeah! Is it Traditional...nope . I am a horrible welder( thank goodness my son is a metal fabricator) but I wanted to give welding a try so I had a go on my floors . I tried flanged seams with plug welds, I tried butt welds , ground down a bunch, welded some more. Got to try out Cleco`s and sheet metal screws and then try to weld up the holes left by them. The floors are in, solid and rust free. I have a grin on my face when I look at the finished product. Not pretty but I did it myself and had some fun doing it. Did I learn much? ... yup, anything that shows...I call my son. Cheers, Scotty
Of you have no welder at all, I would by a MIG, the most all round tool in my shop, for body work. If you want the nicest weld, and wants to do really nice body work, buy TIG/heliarc! If you have no experiance in no/almost no Bondo bodywork, this will be faster to learn! By fare. Mostly when you shut your welder of it's not gonna hurt nothing, and it more adjusteable, because most adjustment is done at the machine, not seat-of-the-pants-flying, on small tricks too go hotter or colder. But if you can find all three used, for the price of a new one, I would do that, because all three have other ability, when used as a side-kick to the other two superheros in bodywork. By the way, you can learn alot about TIG on you tube, but ox/acet you gets someone to teach you!
I have had to fix stuff like that and I can tell you it makes things worse down the line. you can get a cheap mig or a used one for a decent price I only have a mastercraft 120v mig/flux core welder at the moment bought it for about $250 new it will work well for sheet metal
Gas welding takes a lot of practice and the heat can really warp the floor if your not careful and keep a wet rag handy. I prefer mig welding myself. HRP
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