When I first started the body work on my truck I started with the bed, thinking the flat metal panels would be the easiest thing to work. I have completed a frame up restoration of my truck with the exception of the bed. Starting to work with the bed again I now realize these will be the most challenging panels to deal with since they are one thickness and visible from both sides.
The bedsides had lots of small dents and due to my improper technique in removing them I now have stretched areas. One large area in front of the rear fender is a big belly that is about 1/4" higher than the flat areas. It is roughly about the size of the outline of a football (American). It is gradual enough you cannot see it or feel it easily but a straight edge shows it clearly. I have some other oil can effect areas in other parts of the bedsides too.
I have searched and researched ways to deal with the stretched panel and most come down to a shrinking disc or torch heating the area and quenching. Most of the videos I have watched using either method are working a fairly small spot. My concerns with the torch method for a large area is it looks like you can just keep pushing a problem farther out than you started with or end up warping things and ending up worse than where I started. With the disc on a large area it looks like it would take a really long time and with a very gradual raised area where do you start and where do you move to for the next spot.
The fender might break the areas up enough these areas might not show up but on the bedside I am pretty sure it will look wavy unless I can get things straighter.
IMO the donut dolly or a heating tip on a dent puller/stud welder will give you a more consistent shrinking process for more controllable results. The shrinking disc and torch method are a bit more aggressive and thus somewhat more challenging to control the results. Here is a thread that details using these processes (except the torch) to fix sandblasting damage, or basically stretched metal, just as you have. It is a bit of a long read, but should help show the processes to fix your stretches..
Chuck, I've been using a shrinking disc quite a bit on my fenders and other crowned panels. A shrinking disc works by heating (locally) the high spots that it contacts. When the heated spot is quenched, it shrinks. When you repeat the procedure, it works on the "next highest" spot. In theory, it seems like it would be effective on a flat panel, especially on small raised spots. I think that for a large flat area you would have trouble controlling the shrinkage. The shrinking disc probably isn't the solution. I agree with MPandC on the stud welder. You may want to spray the area with guide coat and run a block sander over it to help visualise the highest spots. Work on them first, then progressively until it's flat. Work slowly. Dave Evans
I had what I thought was going to be a big wave in one of my bedsides but after bolting the fender to it it straightened out. Here's hoping for you.
1953 Chevrolet 3600 Fried Green T'mater (Vern) In the Stovebolt Gallery Caution: Political Statement Man who runs in front of car gets tired, man who runs behind car gets exhausted.
Thanks for the suggestions and encouragement. I appreciate the help a guide coat and long board can give but I am a long way from that just yet. I don't have either a shrinking disc or a stud gun. I have do have several torch sizes including a tiny oxy-acy jewelers torch that might be easiest to control the heat and size.
Harbor Freight offers a stud gun kit for $99. I found a lot of references that had good luck with that product. Most of the people who reported a problem were using an undersized extension cord. The package states in big letters it needs a dedicated 20amp service (which I have). I don't normally buy cheap tools but I doubt I will have much need for a tool like this once my bed is done. Robert, the experiment on the deck lid in the thread you posted was interesting but if I have to make that many strikes I am not sure the HF tool is up to the task. I really don't want to spend a lot of money for a better unit.
I have given serious consideration to purchasing new bedsides from Mar-K. I have only described the trouble I found in the first 2 feet of one bedside. A quick application of a straight edge shows other areas that will need similar but smaller areas shrunk. I am sure I could make the outside of the bedsides look good because the fender covers so much of it. Its the 6+ feet of straight run on the inside of the bed that is making me wonder about new bedsides.
The donut dolly may be a viable option but I have reached a point where any additional hammer and dolly work just makes the situation worse and I am not feeling confident that I would do much better trying to shrink using the PVC or other donut.
Chuck, most people will try torch shrinking with a hand held propane or too large an O/A tip, causing larger areas of heat than is easily managed. If you have a jewelers torch, I would give that a go with a soft flame to prevent burning a hole through, and you should be able to do nice small circles. That small of a torch you should easily duplicate the same results as the heating tip provides. I would start by heating circles about 1/8" diameter or less, but more importantly, you want to consistancy in whatever size heat circle you do use. Even if you're thinking of new bedsides, trying this out on the old ones will only cost you a bit of gas and your time. Whether you use the bed sides or not, the experience may prove useful in repairing other damaged areas where panel replacement is more challenging than just bolting on new ones.
More great advice! Thanks so much guys. Neil, I did watch that one and its actually what scared me from jumping in. His corner was tied down and he still chased the oil can out a ways. I was afraid I would just chase ripples all over the bedside using that kind of heat.
Thanks again Robert. I will do a little practicing on an old fender and then try the jewelers torch on my bedside. I had the same thought as you- if I really screw them up I can still go the new route. Aside from the expense of new parts I have gotten a lot of pleasure reviving all the other old parts and would rather save these too.
There seems to be knowledgeable people on both sides whether quenching with water after heating (no matter what the heat source) helps shrink the metal or not. From what I have read there is perhaps more support that rapid cooling has no effect. Any opinions?
I have yet to conduct any definitive tests on the torch shrinking but IMO cooling the area with water (regardless of application method) will not have any effect on the amount of shrink, but the benefit is that it will "encourage" the shrink to happen more quickly to speed up the process of seeing what reaction the panel has taken for planning your next move... Allowing it to cool naturally should shrink the same amount, but you may have to wait for that to happen so you know where to proceed. In choosing your cooling method (if you so decide), a damp rag should work more effectively than a spray bottle, as it doesn't go into an immediate evaporation, you'll still have some cooling medium there....
I tried using the jewelers torch and have improved my situation but I am not yet satisfied. In case anyone follows this I thought I would comment on my experience metal shrinking with this mini torch.
The plus side- the torch is very light, small, and doesn't burn through much gas. It is very easy to control the amount of heat the unit puts out. It fits in the palm of your hand and is easy to hold on to while hammering or quenching with the other hand making it pretty easy to use with just one person.
The down side- it takes a long time to get a spot red hot. There is a very large area of metal that gets quit warm before the small cherry spot. What happened to me was the line of spots I heated became a higher ridgeline rather than shrinking down. The surrounding metal appears to have shrunk because when I knocked this back down everything was flatter and the oil can effect in an adjacent area was gone. I still don't have a perfectly flat panel but it is better than it was.
Overall everything is as flat as I can get it with a slapper and the largest flat dolly I have. There are still very gentle waves in the panels when a straightedge is laid on them. Beyond finessing the area I torched a little more, I do not know what I can do to make the panels flat. If I just use filler there will be less than 1/8" in the thickest places but that means an equal amount in the opposite areas on the other side of the panel. Without better metal working skills is this my best option?
I am a big fan of the shrinking disc. I think it's much easier to control than heating with a torch. All you need to do is apply the disc for a shorter period of time and with less pressure, if you're worried about over-shrinking. I have found that working with the shrinking disc is actually a little slower, but surer and more easily correctable. You can always make fine adjustments with hammer and dolly as well. At any rate, I've had a lot of success in removing oil canning and related problems with the disc.
I thought I would make a final post about this for anyone doing future searches. I worked on the bedsides off and on for about a month. That only increased my admiration for real sheet metal workers. I can move the bedside waves around but cannot figure out how to eliminate them short of body filler on both sides.
I have such a little amount of filler in the rest of the truck I really didn't want to do that. I wrestled with the desire to preserve as much original sheet metal as possible vs. getting perfect new bedsides from Mar-K. I have had great success with the rest of the bodywork, including welding in a few new patch panels, but the straight bedsides defeated me. I placed an order for new ones.
but IMO cooling the area with water (regardless of application method) will not have any effect on the amount of shrink, but the benefit is that it will "encourage" the shrink to happen more quickly to speed up the process of seeing what reaction the panel has taken for planning your next move... Allowing it to cool naturally should shrink the same amount, but you may have to wait for that to happen so you know where to proceed. In choosing your cooling method (if you so decide), a damp rag should work more effectively than a spray bottle, as it doesn't go into an immediate evaporation, you'll still have some cooling medium there....