The Stovebolt Site Forums The Shop Area Paint and Body Shop More floorboard welding questions.

My first attempt at butt welding with my new Miller 211.

I uploaded a video on youtube and commented:

16 gage metal, #30 wire and using the auto set. I probably should have used smaller 24 gage wire and hit each spot a shorter time. I plan on butt welding my 16 gage floorboards to the existing 18 gage. I haven't done this too often, so any input would be appreciated.

When I get some practice and attempt to weld the floorboards in, do I have to do both sides? Maybe just the outside and sealer on the inside? Or??

Also as mentioned in the video comments, the new floorboards are 16 gage and the existing ones are 18. Will this cause any problems?

I previously welded some 1/4 inch steel with my new welder and really love it!

You are using gas right? You can will need to weld both sides, or run it hotter. I noticed the angle of your wand when welding, I use more of an angle, but thats subjective. Its good to move around, like you did. I think you need to crank it up a bit, then you wont have to weld both sides.

Remember, everywhere you weld, you will be putting a 1/8th or so inch skim coat of bondo on. I dont care who you are, you wont get around this. Most of it will be sanded off, but it will help smooth things (both sides). You are doing just fine! Its a matter of experience with your welder. Nice machine!

Thanks! Yes, I am using 75/25 gas, adjusted to 20 lbs when the trigger is pulled. Might have been a little windy in the garage. I will change my settings and practice some more. I didn't know about the bondo.. I thought it was welding and grinding over and over until it was smooth.

No Chuck.. not alot of the best of them can do that. Although for awhile I was convinced you could do it. No, because that heat over and over distorts the metal. Heat is not only generated from welding, but from grinding too. Good penetration, then a skim coat of Rage Gold. Clean the area after grinding so the bondo adhers properly. Some people like to do epoxy primer before bondo. You research and decide what you feel is best.

The better you get at welding the less bondo, so skill really plays an important part.

Well after having the replacement floor boards for 25 years, I finally went for it. I butt welded to the existing angled toe board and used plug welds at the flat floorboard areas. I was surprised at the results. It was easier (and funner!) than I thought it would be. I wish I would have done this a long time ago! I am re-modivated again! I realize I am running out of time and better get to restoring. I just plan on getting everything back together with a not too fancy of a paint job. Figured I will paint the interior with black rustoleum and the exterior the original cape maroon. The dash was painted black many, many years ago by the previous owner and the paint is in fair condition, so I will leave it like that. I just turned 64 and at the previous rate, I will be too old to drive!

I have found that I get a lot of pinholes between my welds as I do the fill-ins to butt weld sheet metal. Instead of obsessing on adding more weld wire, I mix up some JB weld and work it in the small voids and smooth it out.
I figure it adds some strength, looks good, and unlike bondo is waterproof.

Thanks. I was thinking similar. The more heat, the more warping, so I thought about doing just like you mentioned. Thinking about JB weld or maybe something that is also waterproof and comes in larger quantities.

Fellows make sure if you plug any holes in the floor boards that you fill the epoxy all the way through and spread some epoxy around so it will not come loose from vibration down the road. If you were to countersink a hole of 1/16" then the epoxy would not come loose. Ideally both sides. I have used it at work and have had it come loose after a few months without counter sinking. Marine Tex is much stronger and a little more pricy than JB. but has 46,000 PSI.
62blue
Don

I have used Por-15 patch and putty with good success. do a search and check it out.

I am big into POR-15, and although I saw the product you mentioned, I never tried it.

Any opinions on skimming on some allmetal product prior to primer?

I was thinking allmetal, but not sure if whatever I use needs to be flexible or not.

I don't know if I would consider myself a "welder", but I'm doing it and learning as I go.....experience is the best teacher, and all that.
I find when welding two different thicknesses of metal, it's better for me to begin the weld on the thicker section (16ga. in your case) and move to the thinner section (18ga. in your case).
It may be psychological, but that still works for me too!
Good luck!

Some comments on your YouTube video...


The first weld that you tacked, you stopped and then added more on top a second later.. Typically if you didn't get full weld penetration at the onset, welding on top is "blobbing" and still does not provide full weld penetration, only a taller weld to clean up. If you look at the back side, despite more weld on the front side you can still see the panel seam on the back side. Our purpose in welding these panels together in any rust repair is to duplicate what was originally there. In order to do so, your welds must have full penetration so we can go back and dress the welds flat. Looking at the other welds, many do not show full weld penetration. I would take the machine off of autoset, just rotate the knob slightly counter clockwise enough that the blue light goes out. Now, turn the heat up from your 16 ga setting to about 14 ga. Try your tacks again, and you should be able to decrease the time of trigger pull. Basically, you want full weld penetration, which the increased heat and wire feed gets you, but less buildup for less cleanup, which a decreased trigger pull should get you. If you can practice this and get proficient at it, it will help out with your MIG welding.

Next, most of the panels we weld on the vehicle are in free air, not laying on a metal work bench, so I always recommend to have the weld seam also in free air. If you rotate your coupon so the weld is centered in the slot, this would provide that scenario. Your practice pieces should duplicate as best as possible the same conditions you have in welding on the vehicle, as this helps to get your machine and your techniques "dialed in" to the exact same conditions you will see in welding your new parts in.. A steel work bench acts as a heat sink, which could also be causing some of the weld penetration deficiency.


You should be able to weld in this panel without the use of excessive filler. Any weld on sheet metal is going to shrink, so first and foremost, look for access from the rear side to be able to use a hammer and dolly to add some stretch back in the weld and Heat Affected Zone (that which is blue in color) when choosing where to put your weld seam. Generally, on parts like the rocker, don't worry about cutting a part of it, use the entire part. Panels like the rocker that don't have access for planishing, you are better off using the entire part and using plug welds to attach, which will have less shrinking issues than that of a weld seam. So worry less about using the least amount of new metal as possible, and more concern with planishing access, or methods that provide less shrink. Ideally, with sufficient planishing of the weld and HAZ, one could effect this repair without any filler. Realistically, we all need a little bit, but I would suggest focusing on the weld and planishing process and leaving filler as a last resort. Also, pinholes or missed spots between welds is a weld process issue, don't fix a weld defect with filler, correct the weld process.

If you do need to add a seam, make it near a higher crown area or a crease, as these areas will help to minimize the warping effect. If your patch panel has a stepped edge for lapping under, cut it off and do a butt weld. Lapped seams are prone to causing ghost lines in your finished paint, as seen here in this wagon tailgate, the bottom was repaired and attached using a lapped seam:







Similarly, using sheet metal of different thicknesses may cause this same issue. Anything on the exterior of the vehicle should have repairs done in as close to the original thickness as possible. I would suggest to continue practicing the weld tacks (in free air), adjusting the heat and wire feed settings until you get full penetration weld with each tack before moving on to your good sheet metal... My tutorials link below also has quite a bit of info on welding sheetmetal᠁.

Chuck, I did some digging and found the thread I had posted earlier on MIG welding... Give it a read, it may answer some of your questions.


https://www.stovebolt.com/ubbthread...welding-tips-tricks-for-sheet-metal.html

Thanks everyone for the great info! It is pretty much a done deal other than lifting off the cab to get to the firewall. A little welding is needed there on the other side of the joint. Once that's done I can seal the weld and start sanding the cab for painting.

Primer-surfacer takes care of those pinholes.

Pin holes in welds are a welding problem. Perhaps a slight change in your technique or welder setup could resolve this to eliminate the pin holes, removing the need for another step in the process.

I know that, just can't seem to find the right change. I am using a cheap flux core MIG, so maybe that is the main issue. I need to invest in some practice time and scrap.