Guest Anonymous Posted August 2, 2001 Share Posted August 2, 2001 All, I need the collective knowledge and wisdom of the forum concerning a solution I am seeking to removing spot welds, hopefully without drilling or using a spot weld drill removal tool, because both methods are either too slow for removing hundreds of welds or destructive to components that I wish to, salvage, customize and reuse. In my search for solutions to overcoming certain structural limitations of the S30 unibody related to customizing it with recessed side pipes and into convertible forms, as earlier introduced in my new Sleek Z Project website, I am considering an approach of completely disassembling a S30 shell into all it's original factory metal components. My good fortune is that I have several stripped shells at the ready to be practiced on. Kind of a "reverse engineering" approach, if you will. What I am looking for is a method to heat up spot welds in such a way that they will "let go" or melt to a separation point without gross deformation of the the 2 thin sheet metal pieces that are spot welded together. I am wondering whether a spot welder machine or mig/tig/torch welder can be used in such a way as to cause this to happen? Anybody have experience or suggestions? Would any body know an experienced body man or metal worker that I could correspond with about these questions? I don't have a spot weld machine here right now, but can obtain one for experiments. Also have all other types of welders at my disposal if I need one. Thanks much for any help you can offer. Eric Neyerlin Quote Link to comment Share on other sites More sharing options...
Mike C Posted August 2, 2001 Share Posted August 2, 2001 I'm not an expert on welds, but unlike solder which comes in many different temp ranges, the weld melts at almost the same temp as the steel. So you can take jewelry apart, but my guess is you'll just burn the S30 to the ground Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 3, 2001 Share Posted August 3, 2001 My fear exactly. I realize that a solution on my terms is not likely, but I want to hear what others suggest before I start any drilling approaches. thanks, -eric Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 3, 2001 Share Posted August 3, 2001 About the only thing I can think of is putting a spot welder back on the spot, heating it up and then try with a bit of pressure to pull it loose. If there is hundreds of these spots though I can't guess how it might distort using that method or even if it would separate cleanly. I feel your pain though, I've had to take alot of spots loose on work I used to do and drilling them is a pain, the drill bits really don't like that hardened spot weld very much after a while either. Hope you find a better way, Lone Quote Link to comment Share on other sites More sharing options...
Ray Posted August 3, 2001 Share Posted August 3, 2001 If you have several shells... Take and isolate the speffic pannel you want by trimming arround it so that all that is left is the edge of the adjacent panel where the welds are. Then use a small very hot cutting tip on the scrap edge quickly. This will get rid of one side and keep the part you want to keep in tack with little or no warpage. the goal is to melt off the area between the spot welds quickly...Now one more time quickly... then use a grinder to clean up what is left. I have tried the drills, great once they are new cobalt works best but they dull due to the face the weld surface is hardend in the welding process. now remember be careful and the goal is to heat it quick so heat doesn't transfer to the panel you want to save... try it a few times and you will get good and it is quick. Now if your car has rust or you dont have a small cutting tip. You can trim the panel the same way just use a grinder on the welds. This is the only fast way I know. I learned this after drilling out all the spot welds that attach the front clip to the firewall.....that took forever....when I got the good front end to weld to the tub and expairmented, ended up using this way to trim the parts clip and it worked great... BTW a Sawzall works great for cutting Datsun sheet metal nice and clean..... Good luck Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 3, 2001 Share Posted August 3, 2001 LoneRider, Yes, this is my experience also and I hate using those expensive, short lived spot weld removal tools. Waste of time and money in most cases. When simply removing a panel for a customer off a wreck that will never be rebuilt, I prefer to buy a high quality carbide tip of the right size, carefully center it on the spot circle and drill straight through both panels with a high speed power drill and get on with my day. My thinking is that, with a specially honed, thin metal chisels at the ready, that a spot welder might be able to heat the spot to a point that the chisel inserted at the correct moment, could slice or separate the heated up weld point before it cools. That's a long shot, I realize, but I never overlook the obsurd solution during my pursuits. Another thought is to re-examine metalurgy techniques to see if the metal spots could be converted into states of crystalized fatigue by some heat and cooling process that I do not yet know about, that could cause them to break loose easily?? I am going to trip on down to a metalurgist lab next week that a buddy just turned me onto, and see what they have to suggest?? Several of my current projects place a lot of emphasis on careful, pristine work to allow several unusual reassemble projects, not only for actually building a custom prototype for the future, but also to use to create a few visual Z customizing tutuorials and perhaps even an exploding model effect for a QuickTime movie presentation I have toyed with in my imagination. There's also renewed need to cleanly salvage as many older 240Z body panels and structural parts as possible these days, now that Nissan is closing out much of it's older parts inventory. Hopefully some creative body guy is going to pop up with a great solution yet? ____________ btw, lonerider, your projects in Sacramento came up in a discussion with Dan Juday, another Hybridz regular, while I was photographing his custom 240Z project in Rio Vista last Monday. Click HERE to see first preview photo of his TPI V8 engine installation. If you get a chance, it would appreciated if you could send me your email address to zparts@jps.net so I can post to you directly about the Sacramento Z and V8 swap scene when I have a question. -Eric Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 3, 2001 Share Posted August 3, 2001 Ray, Sounds like some worthy advice and experience to test out. Let me see what others suggest and then I will test a few of the most feasible and report back afterwards. Thanks, Eric Quote Link to comment Share on other sites More sharing options...
RPMS Posted August 3, 2001 Share Posted August 3, 2001 Eric, In my job, I do some spot welding of polypropylene pieces with an ultrasonic spot welder. The materials in question are different, but the techniques are the same. I've occasionally had to un-do a bad weld spot, and here's what I've found. 1) When you apply the arc to the weld spot, you will liquify the metal on both sides of the weld. Once this is done, the metal pieces will no longer be bonded at that spot - the problem is, the two pieces will be bonded at the next weld spot a few inches away. Unless the pieces are flexible enough to bend away from each other (without distorting them unduely) 1/4 inch or so, you're no better off than you were before you struck the arc. 2) Precision is important. If you can't hit exactly the same spot as was originally welded, you'll end up with a fresh weld puddle right next to the solid weld spot you're trying to remove. True, you could maintain the arc long enough to expand the puddle to encompass the welded spot, but that might get real messy, real quick. You pose an interesting challenge. The solution should remove welds quickly, cleanly, and easily. If carbide tipped drill bits wear out too fast, what about some type of carborundum grinding bit? Maybe you could grind the weld down instead of drilling it out. Or maybe a blast of inert gas while the weld spot has been re-liquified? That probably would just result in a larger, hollow spot weld, huh? I suppose that if you hit the weld with a lower amperage jolt than would be necessary to liquify the metal completely, you might be able to pry the pieces apart while you zap them. I believe the key would be to soften the metal in the weld w/o liquifying it. Good luck, and let us know what you find out. You know, I envy you, getting to play around with Z cars all day, and getting PAID for it!! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 3, 2001 Share Posted August 3, 2001 Scott, I think you have expanded the brainstorming session in a promising direction. Although it has been many years since I practiced arc welding, I usually find that I am a farily quick study of such techniques. What I need to do is round up a bunch of different welders, make some custom tools that I think will aide my efforts and start practicing a bit to see if I can zero in on a "feel" for the metals and techniques suggested so far to see if I can develop a practical method and rhythm with a technique that works. Your suggestion of using low amperage to soften the weld to allow prying apart appeals to me. What would be your guess as to how long (seconds?) the heated up weld would remain susceptible to being sliced through with a very thin, hardened, metal chisel with a 8 lb hammer blow where the 2 edges of joined metal were easily accessible to insert such a chisel prior to heat up? Nissan joined many unibody sections together with paralell edges of both panels exposed (and susceptible to rust penetration). For example, the upper rocker cover where it is spot welded to the inner rocker sill. btw, selling Z Parts is not exactly what I would term a "growth industry", but you do meet some pretty interesting Z enthusiasts along the way such as in the great forums at Hybridz. If you want a more dependable income, I'd suggest playing the Lotto more often, but it you want to piss your corportate boss off everytime he refuses you a raise, remind him that you have a Z Parts Website business that beats your day job any day of the week. No promises about getting the raise, but you may be delighted to know that at least you still will have something to keep you busy if he shows you the door!! Funny thing was, after having had so many Z's to drive and play around with for so many years, my interest just burnt out about doing conventional Z projects and I took a long break. I parked my intercooled 240Z furbo in 1994 and let it rust away in a corner with tons of newly installed performance equipment. I thought that the 74 Fairlady ZG that I bought in 1992 would inspire me to fix it up and tool around in it, but it hasn't and it just sits outside my door gathering dust. But these concepts that I have loosely begun to refer to as "Sleek Z Concepts" have been brewing in my head for so many years that I now am feeling kind of "hot to trot" about bringing some of them out of the concept stage and into the tangible world. Kind of risky to announce such intentions, but now that the cat is out of tthe bag I feel pretty motivated to push the effort. Besides, if you have ever attended the annual Shasta Datsun Meet in Northern California, you can't help come back from there without wanting to build a cool new project car to take back the next year. That meet is really contagious in that way. I love it up there. Thanks much for the great suggestions, - Eric Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 3, 2001 Share Posted August 3, 2001 I just repaired a rusted radiator support panel in my 71' HQ Holden last weekend and had to undo about 50 spotwelds The best way i found was to heat the spot with a small tipped oxy/acceteleyne torch and then split the two pieces of parent metal with a thin cold chisel or since i didnt have one small enough a piece of steel about 3mm thick and 50mm wide with a chisel like tip. it pulled apart fairly easy and with little enough distortion that i flattened it with a dolly and hammer in 2min. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted August 3, 2001 Share Posted August 3, 2001 Eric, What Rob just described is exactly how I have spereated welds in the past. What I actually did was make a tool with round steel stock for the handle, and used a piece of 1/8 inch thick 1 inch wide and 4 inches long that I made an edge with (Very Sharp, I might add..) to use as a chisel of sorts. I took a torch and heated the spot weld and then took a 2# hammer and drove the homebuilt tool between the two sheets and the spot. Popped right off, and I was able to do this quickly on several sections. Mike Kelly Quote Link to comment Share on other sites More sharing options...
Jeff Posted August 3, 2001 Share Posted August 3, 2001 I've been drilling spot welds while doing my rust repairs and wow what a PIA. I'm intrigued by Mike & Rob's method and want to know how long you guys heat up a spot or if you just get it cherry red and then smack it with the thin chisel? This is why I love this forum, the wealth of information is great. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted August 4, 2001 Share Posted August 4, 2001 I don't know how clean you want to do this, but I used a plasma cutter and just burned them out. I did this on an RX7 that was being customized so the holes were no big deal. Quote Link to comment Share on other sites More sharing options...
RPMS Posted August 4, 2001 Share Posted August 4, 2001 Eric, I don't really know all that much about welding steel, but it sounds like Rob and Mike have a good technique to follow. I'd also be interested in seeing how well a TiG torch (no gas, just the arc) would work in that application. Much more precise heating of the weld, and it wouldn't require any consumables - except electrons, and them's cheap. I can buy about 800 quadrillion for just a penny or two! Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 4, 2001 Share Posted August 4, 2001 Like Les, whenever I need quick holes drilled I've used a plasma cutter. We used to turn out 8"-12" flanges all the time where I worked, out of 1/2" mild steel. We didn't even bother drilling holes for bolts in them, took too long. 2 minutes with the plasma cutter (and a steady hand) and you'd have 12 very useable bolt holes. Compared to 30 minutes+ will a drill press to do the same thing, and you can start to see why our shift was so much more efficient than the rest. BTW, we had 100% sucess rate with this method, in the worst possible conditions. Never an incident where drilled holes would have prevented problems. Quote Link to comment Share on other sites More sharing options...
John Washington Posted August 25, 2001 Share Posted August 25, 2001 Plasma cutter is definitely the way to go. I have not cut spot welds before, but have used one a bit to cut some pretty complex and precise stuff. You will have to experiment a little with hole size, but take a piece of 1/4 bar stock about 12-18" long and drill a hole (maybe start with 1/2-inch...depends a bit upon the size of the plasma tip) close to one end to act as a circle template. Hold it tightly over the spot weld to be "blown out," put the plasma tip inside, pull the trigger and smoothly trace the inside of the circle. The spot weld should "go away" with minimal heat transferred into the surrounding metal...unlike with a cutting torch. Quote Link to comment Share on other sites More sharing options...
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