Novice who intends welding floor pans in passenger vehicle. Trying to decide whether to purchase a flange tool for both floor pans, and quarter pans, rather than using butt welds. Thought perhaps members more experience in body repair could provide suggestions. Thank you

dave

 

Butt welding sheet metal is an art and if you haven't done it before I would suggest the flange tool. Heck I can weld fairly well and I would use the flange tool anytime the shape of the body lets me. It gives you more metal to sink the heat away from the weld and you can even use "clecos" (don't know if the spelling is right) to hold it in place while welding.

You also didn't say what type of welding you are doing, MIG, TIG, Gas. In all cases but goo TIG welding I would suggest flanging the panel.

Just my opinion.

Kenny

 

Kenny, appreciate the info. I have an oxy/acyl setup and just beginning to understand how to weld with it. Recently picked up a Lincoln 155 Mig welder, swapped few auto parts, it's an old unit but looks like it's in good condition, not sure if able to purchase parts, will have to look into it before purchasing a tank. Currently looking at the inline flange tool, has a 360 degree rotating head, not sure if necessary, also hole punch of 5/16, may go with cheaper model that punches 3/16" hole. Thanks again.

dave

 

I am sure you can still get parts for that welder!

One trick on flanging...make sure you flange the upper part. You want the flange so it is open to the bottom (lower) side of the car. Why? Easy, water goes downhill and thus will run out, if the flange lip is up, it traps water and junk allowing it to rust quicker.

Kenny

 

If you gas weld on body sheet metal, use baling wire as filler rod, NOT brass. The dissimilar metals will rust over time.

The preferred welding method would be with your MIG welder but only with shielding gas. Don't even THINK about using flux core to weld body sheet metal. Also, you will have to MIG it in a series of small tack welds jumping around all over until you have filled in all of the seams. If you just take off and start running a bead you will warp the heck out of it.

MIG it by putting a tack in a few places scattered around to hold it in place. Then put a tack halfway between the tacks, then halfway between those and so on. Once it is all done, then don't grind all of the weld off. Leave enough so that it stays together. THEN seal the weld with fiberglass reinforced plastic filler to keep it from rusting.

Good luck,

 

I found a "trick" for butt welding - what you do is grind the cut of the original sheet metal's edge to an angle rather than straight - then do the opposite angle on the patch panel, so the mate and slightly overlap. Then "butt weld" down the center of the overlap. The overlap of course is very small but with low heat I find this works reasonably well.

 

Any 'trick' methods for welding floor pans appreciated, taper joints sounds like a good alternative to butt/lap welds. Considered lap joints because it seems to me cutting the floor pans for butt welds would require considerable experience and lap would be more forgiving. Have since browse couple other threads where members recommend weld over adhesive for floor pans, and preferred the butt over the lap for strength. Have some spacers that are suppose to help with butt welds, it clamps the 2 pieces of sheet metal together leaving a slight gap. Purchased some sheet metal from scrap yard and intend practicing with both type joints, if the floor pans come out nice, who knows, may even try a quarter panel. Understand flange tool would be good alternative when it comes to welding quarter panels and the punch comes in either 2 sizes, 3/16" or 5/16", any recommentations on size, or would a drill work just as well.

Appreciate the information of MIG welding, going to purchase the tank within next 2-3 weeks, likely get the larger, or medium size bottle; rather than purchase as I did with the oxy/acyl tanks, may rent at the start and then swap and buy smaller when majority of the welding is completed. Find as a 'do it myself backyard mechanic' the oxy/acyl tanks can go for couple years or so before they need refilling. Thanks again!

dave

 

I generally do flux-core mig welding because it's more convienent. No bottles to buy/rent nor do I have to wait for a gas supplier to open monday morning. I don't know about anyone else but my various gas bottles never seem to empty out when gas suppliers are open. Probably because my "project time" is incredibly late at night on weekends.

If you purchase an electric welder of any kind (tig, mig, arc) you'll find that you'll use it a lot more than your oxy/acyl setup because it's much more convienent to roll the cart around, plug it in, and fire it up. You're not limited to automotive work.

I've fixed mailboxes, welded lightposts together (which saved me from digging up the old one that rusted in the middle, but the bottom was fine), repair mower decks, old metal benches, the lawn cart, wheel barrows, etc. I added an air-actuated snowplow to my riding mower, and even welded mower connecting rods together. I've made tampers (large round concrete thing with a steel handle for squashing newly turned soil), I've welded gates/railings, ride-on toys for my son, made tools and accessories for my lathe & milling machine, welded patches on rusty garage door tracks since I was too cheap to replace them. I even made plant hangers and plant hanger posts for my better half. Left-over electrical conduit or black pipe fishmouthed and the potted plants hang on that. Welded holes in the gas grill, and the list goes on and on and on.

The most fun project I've done was welding patches on the steel inground pool frame when the liner was replaced a few years ago. After the liner company removed water and old liner, they wanted to walk off the job because the steel frame looked like swiss cheese in some places. I told them to come back in 3 days, giving me the time to patch it.

What did I patch it with? Car roofes I cut 'em off at the junkyard using a borrowed gas-powered metal cutting saw (which takes no time at all), then hammered them reasonably flat on the back patio with a block of wood and a big hammer, then cut it up and welded the smaller patches over the holes in the metal pool shell.

A spool of flux core wire and about 40 flap discs later, the pool liner company installed the new foam backing and liner with no troubles at all. I probably should have used galvenized steel but the pool is moving eventually anyway so it doesn't have to survive another 60 years - which is how old the pool shell was at the time (its now 65 yrs old)

I do flanging the lazy way.... instead of drilling/punching holes for cleco's, rivets and so forth, I just make 1/8" deep flanges and clamp them together on the inside with vice grips. Then I run a bead down the length of the two flange's edge, joining the panels. To do this method the flanges have to be short - since you're welding the flange's edge. If the flanges are long the panels can vibrate and any body filler you put between them on the outside will eventually break free and fall out. That's why I recommended a 1/8" measurement - I run beads that are just about 1/8" deep. I also stitch these... meaning I weld an inch, then move 4-6" away and drop another inch bead, and continue to the end of the panel, then start over and repeat until the whole flanged seam is welded shut. This prevents panel warpage.

Metal shrinks when heated to the point where you're welding it together, so short bursts spaced far apart minimizes the "heat soak" into the material.

Once done I wirewheel the bead to remove loose slag and the sooty remains of the flux core shielding substance, and will grind off any obvious sharp edges or weird "drippings" if there are any.

Then prime and paint normally. On the outside I fill the seam with a fine body filler like "Rage Gold" and prime and paint to my liking.