Rate my welds.. sheetmetal project

admin

Hello,I've been lurking here for a while trying to learn as much as possible. I've done welding in the past, but haven't done much in many years. I've got a 68 Mustang that I'm in the process of doing some sheetmetal repair. The car was pretty clean, but had some bad rust under the vinyl roof. After pealing it back it was swiss cheese all around. I got a second roof and ground through the existing roof removing all the welds. And on the new skin, I did the oposite, grinding through from the bottom. The plan is to use structual adhesive to glue the roof at the drip rails and inside the windshield channel. Welding at the pillars. I do have a little bit of sheetmetal repair that I need to do first. I picked up some 18 gauge steel and want to replace a corner of the skin. I'm practicing first to make sure I don't screw up the skin. I'm using my Lincoln 135T, with .030 wire, argon co2 mix, with the setting as outlined for that guage of metal on the inside panel. Any feedback would be appreciated.ThanksJohnThe carThe roofWhere I'm at...Rust I'm going to repair...Practice weld, top side...Practice weld bottom...Welder...
Reply:The welds look to tall. On thin steel like that, I usually prefer to use .023 rather than .030 myself. You will put down less weld that way..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:i would go with a smaller wire size less, not as much wire, and way more voltage. you dont have enough penetration. you should have a mini-bead on the backside on the joint in a proper mig weld. sheet metal welding isnt easy and bodywork isnt something one should just jump into - youve got a lot to learn if you havnt been welding for a while, especially with sheet metal and sheet metal work.your on the right track, just need to lay down a boat load of beads before your ready to tackle the mustang body.I break things for a living...
Reply:Like stated, switch to smaller wire.  Also, on sheetmetal it is better to use a series of tacks.  Puts less heat into the metal at once so there is less chance of it warping.Thermal Arc 210Thermal Arc 95SLincoln Weld Pak 100
Reply:Ditto the suggestions on using lots of tacks and .023 dia. wire.Once you get some some competency on running beads withthe .023....and----able to weld the sheet samples withoutmelt or burn thru---then you can try reversing the polarity as if you're welding flux core...except you're not--you're usinggas. This reduces the heat input into the weld.After more practice by yourself, then try water cooling (via spray bottle or wet sponges, etc.) on your tacking, then on welded sheet samples, immediately after welding, to take the heat out--which if left in, causes big time distortion.Use compressed air to quickly blow off the water and continue.(On low carbon sheet this cooling is not detrimental, despite the whining of the POOH-BAHS to the contrary;I really question if they've 'been there and dun that'.)It appears from your pics, that some or many of the new roof sheetingconnections may or need to be plug welds. Hougen Roto-Broaches doa nice job of cutting holes in sheet--faster/better/cheaper than drills orUni-bits.In any case-you need to study the manner in which the original roof was attachedand 'where', before attempting this for real.Most aftermarket and many factory body panels need a good bit of tweakingbefore they'll actually fit as intended.There's a goodly amount of rust on the supporting framework that you alsoneed to address.Last edited by dave powelson; 03-09-2010 at 12:52 AM.Reason: clarificationBlackbird
Reply:Thanks for the feedback. I've got a roll of .025, will there be that much of difference between it and the .023? I picked up a sheet of 18 gauge that I'll practice on until I get it right. I'm in no rush so I won't weld on the car until I'm sure that I won't screw anything up. The rust you see on the the framework is only surface and is coming off with a wire wheel on my grinder. I plan on cleaning that and the bottom of the roof panel, and coating it all with epoxy primer before I put it back together. The only other rust on the car is drive side floor board that rusted from water getting in. A previous owner installed a stereo, and drilled into the cowl to mount a support. When it rained, the water drained onto the carpet.
Reply:Originally Posted by jman340Thanks for the feedback. I've got a roll of .025, will there be that much of difference between it and the .023? .
Reply:Jman, I'm no expert, just a hobbyist but here is my opinion. I think you have too much voltage and wire speed from the machine and your travel speed is too slow (fat wide beads). The heat dissipation your generating out into the sheet metal is insane and is going to cause major warping that you won't be able to straighten. Also, I agree with the other opinions about wire size, use .024 (or it's equivalent .023, .025). I'm working on a project using 16ga, which is a little easier than the 18ga you're practicing on, but the same techniques apply. The technique I have developed is to run a 2 to 5 second bead (depends on material ga) and then pause for almost as much time then start again; all the time watching the heat dissipation that's happening. You'll get a rhythm going when it's good and by watching the heat you'll know how long to pause or if you need to rest for a while. On this project  I was using my Hobart 120 (115v machine) with .024 wire, settings were 2 (16ga) and wire speed 5.5. I snapped a few pictures to show the bead profile I was trying to achieve during the entire run, but you can see when I slowed too much and got "bulky beads" happening. The first picture is the bead and the second is the backside of the bead (inside the box). Note the "bluish" heat dissipation which goes out from the bead about 1 to 1.5 times the width of the bead. That's what I keep an eye on to pace myself. Attached Images
Reply:Once again, by no means an expert....actually haven't been welding that long, but one whole side of my family builds hot rods and have done it all their lives. One of the first things they showed me is, like steve said, the use of a series of tack welds instead of a steady bead. Also, move around a from place to place tacking between the tacks that are already in place so it doesnt build up a lot of heat in one place. It helps keep the warpage way down.Last edited by jdl95stang; 03-09-2010 at 09:10 PM.
Reply:Not sure why but I became a little obsessed today with needing to try some 18ga so I rummaged around and found a few small pieces. It took a couple good tries to adjust both the machine and myself to get something reasonably presentable. The pics below are not examples of perfect welds on 18ga but hopefully can help Jman340 develop the skill needed to restore that beautiful Mustang. I used the same welder, Hobart 120, .024 wire, settings were 1 (24-18ga) and wire speed 4.5. Viewing the pics, the welds were done from left to right. The butt joint is a single 2 inch bead with just a tiny weave in it. I tried to run it straight but I was fighting an involuntary muscle action to weave  Also my travel speed was a little slow and uneven in a couple places. I'd guess at the 1.25" mark is close to the ideal width and too wide at the start and at the 1.5" mark. The corner joint is done in 10 stop/starts and not enough pause in between them. Each bead is about .25" long. You can see the heat dissipation growing the further to the right I went so I should have slowed down the pace. The second pic is the backside of the welds. Opinions? Jman340, do you have any new examples to post? Attached Images
Reply:Hope to do a few more tonight, will post pictures shortly after. Thanks again for all the interest.
Reply:stock up on grinder discs
Reply:Switched to the .025 and got the following results..Top sideSkip welded, with the last weld from 2 1/4 to 3 1/2BottomCompared to the old welds...
Reply:Wow! Amazing difference. Beads are much narrower, lower and less heat dissipation. I was going to comment that the 2.25" to 3.5" section looked ideal and then read your caption that you skip welded (stop/start I presume) in that area. Looks like I count about 5 to 6 stop/starts in there. That's the rhythm you want to perfect. I use an auto darkening helmet so I can watch the heat as I go along, it's what determines my pace/rhythm. I start a bead of about .25", stop and watch the heat dissipate out and also watch the orange glow in the bead fade. Just as the orange glow fades from view I start the next bead of about .25" and stop, watch heat and orange glow then go. I say about .25" but you'll quickly realize just how long of a bead you can run by the way the metal reacts and how far the heat dissipates. Sometimes you can run a little longer and sometimes shorter. I'll usually do about 2 inches total length with this method and then move to another area of the work piece to allow the heat to completely cool in the previous area. It's all a matter of practice and finding what works best for you. Good luck and keep posting your practice beads so others can provide helpful feedback.
Reply:are you going to be re-covering the roof again or painting ?
Reply:Thanks.Initially I was just going to recover the roof. The paint is pretty nice for a driver, but after all of this work, I don't want to put a new top on it, only to redo the rest of the body later. So, I'm going to do a full strip and paint of the whole thing. Looking forward to a color change too, thinking black at this point.
Reply:This is what you need  http://johnsmustang.com/Catalog/4573/   I used to do a lot of sheetmetal repair and if replacement parts are available use those. You should be able to find the side pillars too, then it would be easy to weld them in place, I usually start by using cleco fasteners to align everything first. Then go around and tack the whole thing in place. I run very short beads, keeping the heat to a minimum. edit* passed over the part where you have a second roof that you salvaged.... if it has any rust I still perfer to use new replacement metal, eaiser to work with....Since you have some old metal see how long of a weld you can do on it before warpage occurs. I've had some that I needed to do a series of tacks to prevent warping.Last edited by BruceTS; 03-11-2010 at 01:05 PM.Synchowave 180SD  Bernard 3500SS water coolerMillermatic 200Parker Plasma Tec 40dvOperating Engineers Local 12
Reply:I wish I could have used one of those. Would have saved a lot of time, but they only make them for fastbacks, and mine is a coupe. As for the actual welding on the car, I'll only be fabing a small piece for the corner pictured above, and at the pillars. The rest, drip rails and window channels, will be done using a construction panel adhesive that use on modern cars. I will have to replace a section of the floor board, but it's pretty small