I have a question on welding gaps measuring 1/16" to max 1/8" on 18 gauge panels. First off I am using a MIG and am unsure if the gaps are too big to fill with a weld. Am I right or just paranoid? I was told by an experienced body and fender man that filling the gap with a gas welding rod and welding with that in place would work. Is that true? The pieces i am trying to weld together are a roll pan on the rear of a truck so I think there is going to be a lot of pressure there so i want it as strong as possible. Any help would be greatly appreciated. Thanks.
I wouldn't go any bigger that 1/16".. any bigger and you won't be able to get the weld to stick with out using a piece of brass behind it to connect the two. You can put rod in as filler if that's what you're talking about... that would work fine. Lots of guys use nails in areas where they couldn't get a tack! Read through Kiwi Kev's thread on chopping this car... http://www.jalopyjournal.com/forum/showthread.php?t=417981
I always try to keep the gaps as tight as I can, but hey I'm not perfect, so sometimes there's some bigger gaps than I prefer. Sometimes I'll cut a strip of scrap to use as a little "filler" material. Just tack it in to bridge the gap and then cut off the excess. It's always worked for me in the past. I don't have the fancy schmancy TIGs and metal cutting tools, so uneven tin-snip cuts and not-so-perfect gaps happen from time to time.
From what I know, the gap should be smaller than the size of your welding wire. But if you can get to the back side of the panel, you can use a piece of copper flat stock against the seam. This will keep your weld puddle from blowing out. If you want it to be really strong, and can get to it, weld the back side of the seam too. That will really fuse both panels and your existing weld together.
I was told to use the width of a cutoff wheel as clearance. This is important on body panels so they dont butt together and cause waves when they heat up. I run my wheel thru the gap and then hit it with tacks, Seems to work perfect for me. Of course there are times when the gap is a little too large (I.e-cut the patch slightly screwed up) then use a copper spoon to help puddle the filler in the gap.
If the gaps are small in length (due to an uneven cut), you can MIG weld dingleberries on the opposite edges, grind them flush, and repeat until they meet in the center and the hole is filled... Gently stab at the newly-welded area with an awl in random spots to make sure it isn't too thin... Oh,, and take your time so you don't overheat the panel and warp it from the heat of welding AND grinding..... I have used this method to fill trim holes when I didn't have a piece of brass to clamp under the hole.... It will look like total shit from behind, unless you do the same thing on the other side after the front is done....
I've had good luck w/the torch and 1/16 dia steel rod on body panels. 18 ga would be ideal to try it with and learn the art. More heat = more shrinkage BTW. So tack and move.
Listen to Pitman, stack and move...I have successfully welded the same thing with the same stuff as you I just took my time. Heat is your enemy on this one if you dont want any cracking later in life... good luck Cheers Hodge
Practice, practice, practice. Yes it can be done. A spot weld on one edge let it cool a spot on the apposing edge. Let it cool Then try to bridge between the 2 berries. move to another area and repeat. It takes time due to the cooling time. The hard part is learning when it's just about ready to drip. I sometimes get out another project to play with while the welds cool so I don't get antsy. It's very easy to rush it and make a mess. Take your time. Get some scrap and give it a try. You are talking about sheet metal so penetration and strength won't be an issue. Heat and warping are a bigger factor to worry about.
on large gaps I try and fill the gap with a rod or wire first. then I kinda do 3 spot welds, 1 on one edge of a panel, then 2 on the opposite side on the other panel, and finally 3 in the center of the two to connect them... do that till you got a tack bout 1/8 inch or so then move FAR away and do another. then keep it up like that till you connect the dots..... gas = heat,, heat = warpage,, warpage = pissed off body guy
Make it an easy repair. Put a small filler piece behind the gap that is wider. No one is going to see it anyways.
1/16 is good and 1/8 is on the outer edge of being loose. Like Chadillac said you can back up the gap with a piece of brass, copper or aluminum also works. Then when you weld whatever you use will just keep the weld from falling though or burning through and leaving a whole. The piece of unlike metal won't stick so you can move it to the next spot. You will actually get less warpage with the gap than you will with a tight seam.
All good advice so far. Dont waste your money on buying gas filler rod, use old coathangers, just sand the coating off first to keep down on the porosity. You can also feed it into the puddle with your other hand, like tig, instead of just laying it in the crack. General rule, the metal thickness, the gap, and the filler rod/wire should be about the same...but if its not you just have to make do. Patience.
Ideally, the least amount of gap possible is what one should shoot for with panel alignment. That allows the panels to be joined without the use of filler rod, assuming one is using TIG or O/A. The width of a cut-off disc is too wide, IMO. The width of the welding wire, as mentioned above, would be a better option. This is not the thing to do. This would be the lazy route and leave a less than desirable end product. If the gap is too wide to bridge with weld, you should cut a sliver of material that lays flush with the surrounding metal to fill the gap.
Maybe a small point, but be sure before you pull the trigger, be on one side or the other of the base metal. Too close to the gap, or in the gap, and you will blow through. Also theres a fine line when pulling the trigger, practice being slightly above the base metal, pull the trigger and bring your stick out down to the work. Being right on top of the work before pulling and you risk blowing through. This is one of those fine points that takes practice.
If you go one the metal meet forum theres a pretty good discussion on this.It said you needed to keep the gap as tight as possible but put a good chamfer on both the patch and the base metal.I have had great results doing this.You can see the penetration coming through the back side well.Most guys i talked to told me mig would not work very well and im sure a tig would be alot better but money and experiance are an issue with me.I have been hammer welding it right away before it cools and it seems to strech pretty good as well.The secret seams to be doing short welds and not getting it hot enough to warp.
Thanks for all the help guys. I really appreciate your time and knowledge. i understand making panels fit as tight as possible is the key but I guess I got a little carried away with he cutting wheel and my patience is something I am working on daily. I am going to go to the metal supply shop and buy some copper or brass to place on the backside of the gap. The way I was thinking is once the welds are ground down, there wouldn't be enough material to hold against the pressure. I will let you guys know how it works out.
I do this a lot and everybody is wrong! NO GAPS! period. If there is any kind of a gap it will get filled with rod etc filler etc and that will become a major shrink point! That gap gives the metal a place to go. If the metal has a tight fit there is resistance to shrinkage, until it sees a gap. the gap will act like a pressure relief point and if you weld thru it with filler etc you'll have a big old warp in the metal that you'll be metal finishing and stretching. NO GAPS!
Everett, pushing Harbor Frieght on here generally stirs up the old kettle, but here goes. They have a welding spoon that is under $10, and at least where I live, you cant buy that much copper for double that amount and you still have to make a handle. Maybe we didn't make it, but Americans still work in the store and the warehouse. And the flaming starts in 4..3..2..1..
Just go pn line and buy it that way I got the same spoon and is the same one that Eastwood sells for $30+ ! I think it was more like $12 but is well worth the it . It's a decent size as well . Look under the welding accessories to fine it . Retro Jim
I am new at this but have found out that anything wider than a 1/16" is harder to weld . You end up having to hold the trigger longer and end up with it getting too hot and warping the metal and having blowouts ! I have the best results with a gap close enough for the weld to penetrate the gap . I use a very fast tack weld to keep the heat down then do the criss cos method of tacks until I get them around 1/4" apart . One I get that close I stitch then together covering 1/2 of the original weld and let it cool for a second or until there is no red then do it again . Some use a spay bottle of water to cool down in a mist and some use an air gun . Both work but I refer just to wait . I DON'T do more than 3 in a row . Just my opinion ! Retro Jim
I am pretty sure Darkk has been a body man for 50 years. I would also go with what he said in this case. A thin backer will likely help in this case, and the original poster can try to do better on the next job. If you don't think he could end up with "a real mess" by trying to fill big gaps with a mig, you must be overly optimistic.
Using a filler rod about the same size as the edge of the door.. tack it on grind it down.. takes time but works great.
There's a difference between using a temporary backing material while welding, and welding a strip of metal in on the backside so that there are 2 overlapping layers of metal when the job is done. The former is acceptable, the latter not.
Hey, Using the ''glob & dobb'' i.e. ''dingleberry'' buildup method of gap filling can lead to problems with the weld in the future. What you have is different bits of metal in the area of the gap you're trying to bridge, all heating/expanding and or cooling/contracting at different rates. The metal in the weld area doesn't ''knit or flow'' together as it does in a gas or tig weld (yet another reason I detest squirtgun welds for sheetmetal repair) This can lead to pin holes in the weld and ''whitness or ghost lines'' in the repair once painted. Some guys cover these ''problem welds'' with ''Kitty -Hair" and plastic filler, once they've ground the ''proud metal'' flush, usually creating thin spots next to hardened welds, and more cracks in the panel in the future. Zero to an RCH gap between the metal, 0.23 dia. wire on spotless metal with quick, well spaced tacks will yield the least grief for you. Now would be a good time to start your gas welding study, and leave the squirtgun welding to the late model collision guys and the ''putty boys '' " Do not be to quick to drink the Kool-Aid"
Back in the 60's & 70's we use to use coat hangers as welding wire with a torch . Worked great . Coat hangers do work well around doors to fill in the gap on the door edge . Can also use to help repair drip edges too . Retro Jim
i got one of them horriblefreight spoons, very cheap, works very good, even has a nice handle.....think like 6 to 8 bucks, can`t even get a copper tube for that, becuase regardless of what i`ve heard here, gaps are inevitable.......anyone who says otherwise is full of it.......its gonna happen....
If you want to do it right and even consider doing some post welding moving of the metal in the weld area listen to OJ, no gaps! If you can you should only apply filler rod if you are going to burn a hole otherwise fusion weld. This means gas or tig welding not the "mud gun". If you are a "bondo bandit" then use coat hangers, weld filler material in the gap and fire up the cement mixer and start mixing the bondo. Rex
The Jalopy Journal
