![]() |
Hotrodders Bulletin Board
Home · Bulletin Board · Project Journals · Tech Article Wiki · Knowledge Base · Photo Gallery · Classifieds · Company Reviews · Calendar · T-Shirts |
|
||||||
|
|||||
![]() |
|
|
Thread Tools | Search this Thread |
|
#1
|
||||||
|
||||||
|
Dent Repair
Hi Folks,
The '40 Willys I'm currently working on has about 90 percent of the roof covered with dents. Not small dents, like hail damage, etc., but big ol' nasty lookin' things. I'm going to use the text that Wray Schelin wrote a few years ago on the jaglovers list and add a few pictures to it. Wray covered the subject very well, so no reason to re-write it. Tools for Removing Dents By Wray E. Schelin How smooth are your stripped body panels? That is the question you need to know before you advance to the primer stage. If they're not smooth you can fill them with bondo and heavy primer- but if you do so you run a high risk of a early paint failure and all your work will be in vain- or you can smooth them by accurately working the panel back to a smooth condition. If you rub your hand over the metal and feel low spots or high spots, you can be sure that they will show . Before you get your spray gun out you should be able to rub a panel in any direction and feel nothing but smoothness. If you choose smoothing instead of filling, I'll share with you the technique that I use and some of the tools needed. First the tools: All body tools should have smooth working surfaces; hammers, slappers, and dollys are like printing presses, they will transfer the imperfections on their working faces to the metal over an over. Its best to take the time and smooth your tools first , because any imperfection transferred to the panel can make itself known later in the topcoats,as a paint shrinkage depression. The higher quality body tools are made of heat treatable steel. You should have at least one hard hammer and one hard dolly- for hammering welds. The reason for this is the welds are harder than the surrounding metal and if you flatten them with a non hard hammer you will mark the hammer and then you will have to keep smoothing it. The working faces of hammers and slappers should have a very slight crown to them and the edges should be radiused. With the edges smooth and the center crowned slightly, you will not mark the panel if you inadvertently strike with the edge of the tool. The slapper is the most important smoothing tool. You can make a slapper out of a old rear leaf spring. Car springs are harder than welds, so they will not mark up. My slapper has a working face of 2.250" by 5". The thickness is .250" and the unbent starting length is 14". You can also get a single spring leaf new from your local truck spring rebuilder. You can cut it to shape with a cutoff wheel or a torch, but cool it quick so you don't anneal it. I bent mine with an offset of 1.625" . The offset allows you to affix a wood handle and provides the clearance for your fingers. Heat with a torch to bend the offset and then narrow the handle end to a width of 1.375". The narrowed part is 5" long. This slapper will smooth all body panels except for concave areas. For concave areas you will need to make a special slapper or use hammers. Once you start to use a slapper you will retire your hammer. You will also need a few dollys. I found most of my dollies at flea markets for a few dollars each. Three or four dollies will be more than adequite to deal with all the different shapes and contours that you encounter . Each dolly usually has several different contours and crowns. As long as you have a straight edge , a low crown, medium crown, and a high crown you will be able to smooth any panel. Don't hesitate to alter the dolly to fit a need ,grind them with a body grinder, to rough shape then use a DA sander- with finer and finer sand papers- in rotary mode to achieve a fine polished finish. Next you will need a body file and holder. The holders have a turn-buckle on them to allow you to flex the file to a concave, flat, or convex shape. The file that I use I was able to order from my local welding supplier. They are a dealer for a German company called Pferd. I got a Pferd catalog, an found that they offer a 12 tooth per inch body file , which is considered a fine cut body file. Most of the files that I had seen previously were 8 or 9 teeth per inch which are coarse body files. I like the fine file because I can use it on aluminum , steel, or body solder. When I use it on aluminum I load the teeth with a candle wax, this allows you to skate over the aluminum without digging in and making gouges. This type of file is 14 inches long and has cutting surfaces on each of its sides. On one side I grind the edges smooth in effect killing them so they do not dig in as you skate the file sideways. Pferd also sells the holders and a multitude of different style files and abrasives, all are of the highest quality available anywhere. Pferd has distribution centers all over the world. In the USA they can be reached at Pferd Inc 30 Jytek Dr. Leominster, MA 01453 Phone 508 840-6420 In Australia: Pferd Australia (Pty) Ltd. Moorabbin, Vic. 3189 8 Capella Cresent (03) 5531946+5531933 You can also try your local welding supply house and they might have a catalog. Another item I use is a large magic marker or felt marker. The ones that I use are called magnums and they mark a swath about 1/2" wide with a tenacious ink that dries very quickly. I like red ink the best. A heavy duty 9" body grinder is the most expensive item needed. You can use a lighter duty 7" grinder but it won't work as well as the 9" in all cases. Also a 9" 120 grit grinding disc. Grinding discs when they are new are very sharp when you run your finger over them , after grinding a heavy piece of steel for a few minutes you will dull the disc. This is how I prepare my discs, purposely dulling them to make them suitable for use. Lastly you will need the Amazing Shrinking Disc. I mentioned this tool before in another post, it is a 9" disc of .050" stainless steel with some ruffles pressed into the outer working surface. This tool is most effective when used with the heavy duty 9" body grinder. I can't say enough about how good this simple tool works. ![]() In my next post I will explain the process that I use in conjunction with the earlier mentioned tools. For many years I haphazardly removed dents with a method which always left the panel in a improved state, but not perfect. I frankly didn't believe you could restore the damaged metal to a state were no filler other than primer would be necessary. Like most things once you master them they are quite simple, all you need is the determination and the correct method. Regards, Wray E. Schelin Removing Dents by Wray Schelin -------------------------------------------------------------------------------- In the last post I described the tools necessary to completely remove dents, waves, and dings in your body panels. In this post I will share with you how I use the tools to achieve a panel smoothness that will require very little or no bondo filler. It is best to keep your bondo use down for two reasons. One,bondo use is not craftsmanship, its just a cheap substitute. If your trying to achieve a high standard restoration- in my opinion it is best to have the craftsmanship on more than just what you see. The value of these cars is more than just the dollar amount. The second reason is, if you keep your substrates (bondo fillers and primers) to a very minimum and apply just enough topcoats you will have an ideal thickness of paint coatings. With an ideal thickness your paint system will be able to expand and contract with the steel and aluminum surfaces of your cars body as it heats and cools. This correct thickness insures you against an early paint failure. Coatings can fail for many other reasons, but too much paint and filler I believe is the most common culprit. The most surprizing thing about high quality metal finishing, is that is not that difficult to do; but it does take patience, good eyesight, a fine sense of touch, and the tools that I previously mentioned. First what's fixable and what's not. If you have, say, a 120 front fender that was severely damaged in a accident many years ago on its leading surfaces, an was quickly repaired by sewing up tears with brazing rod, crudely hammered out, ground very thin, and then filled with bondo, forget it; in that case you are probably better served by replacing that heavily damaged section. Another impossibility is an area that has been incorrectly torch shrunk; what had started out as an earnest limited attempt, inadvertently expanded to large area, leaving heat damage with heavy intractable waves. Fixable dents and damage, listed in a descending order of severity: Bodged past repairs that are still fixable, because the metal has not been ground too thin, Collision damage with stretching and tearing, Sandblasting with excessive pressure causing a wave effect, Smoothing out the seam of a butt welded patch panel, Small dents with little or no stretching, I 'll share with you how I remove a small dent . An easy example will work best, so lets say, its the rear fender of a XK120. The dent is in the middle of the rear section of the fender, and its is about the size of your fist, sunken in about 3/4" in the center. All paint and undercoating should be removed first. I would first select a dolly that has a crown that is close to the fender; in this case that would be a medium crown. Using a glove to protect my fingers I would palm the dolly and lightly tap it against the bump on the inside of the fender; carefully watching the progress of the rising depression. I would use this process until I got the dent up to within 1/8" of the surface. This will happen within minutes- this is called roughing out the dent. Next I would hold the dolly tightly against the center of the damage , on the backside, while I use the slapper on the front, tapping the circumference of the dent. This is a dolly off action, the slapper and dolly are not clashing with each other, they are beside one another. I would keep tapping away with the slapper, moving the dolly tightly with some force, against the lowest area of the dent. Slowly the dent will rise to very close to the surface level. The slapper does this operation very effectively because it has such a large surface area, compared to a hammer. With a hammer you're hitting a smaller area and you might dent the area you're hammering against because it will yield easier than the center of the dent. Roughing and slapping the dent has reduced the dent by about 90% and progress was swift. The next stage of metal finishing requires the bag of tricks and the tools. The problem that you encounter at this final stage is, you have trouble seeing what you're doing because your actions have to be small. When you were roughing you could easily see the metal move closer to the surface; but now you might only have to move the metal forty thousands of an inch or less to reach the true surface. At this stage a common practice is to use a pick hammer. In my opinion a pick hammer has many drawbacks: one- you need room to be able to swing it; and generally the hammer itself might be 6" or more across the head. Two- it is very easy to over hit with a pick hammer and cause irrepairable damage. Three- more likely than not you will not be able to strike the low spot, instead you will hit the high spot worsening the problem. The safest bet is to retire your pick hammer. This verdict also applies to the bulls-eye gimmick tools which use a C shaped frame to guide you to the elusive low spot. If you go down the bulls-eye road you will find your garage populated with many expensive sizes and versions absolutely needed to remove all those pesky dents and dings. You will always be one bulls-eye tool short. What I do at this stage is coat the damaged area entirely with the 1/2" wide red magic marker ( thats a US trade name for those who might not be familiar with them- there is no magic, its just a felt ink marker) Next I draw the fine body file over the area, just lightly skimming the surface, this will quickly reveal the high and low spots. The object now is to raise the low spots. You can do this by placing a dolly with a high crown surface tightly against the low spot. You will only be guessing at this point unless you have x-ray vision . You find out where you really are with the dolly by lightly slapping the surface, with the the slapper a few times, trying deliberately to strike the dollies crown. If you are successful - and you probably will be, because of the slappers large working surface- you will hear the ring of the contact of the metals. Slide the slapper to the side, but leave the dolly where it is. You should be able to see a 1/8" diameter ( a 1/8" inch affected area will raise quickly with little force , the size of the mark made when you slap it determines the speed of the metal rise. 1/8" is fast 1/2" is slow) clear spot, or slightly less inked, in a region of the small low spot that you were raising. If you goofed and hit a high area instead you should be able to see a difference there too. Whether you were in the right area or not is not important, what is most important, is establishing where you are and being able to adjust . Watch the trail marks left in the inked surface and you can steer the dolly, on the backside, easily to where it is needed. Slap lightly, slowly raising the low spot. After a few minutes, refile the area and your progress will become apparent. You might have to wash off the marker ink ; re-ink, and refile several times. Each working of the area will reduce the size of the low spots. Remember that the filing is meant just to scrape off the ink and not to reduce the thickness of the metal. The force and stroke of the slapper will be less as you progress. When you have reduced the low areas to less than 1/2" in diameter, and when you rub your hand over the area you still slightly feel them, you are ready to use the shrinking disc. The condition of the metal at this point is stressed and springy as a result of all the trauma inflicted on it. The original damage has been raised but in the process the metal has been stretched a little. If you applied bondo at this stage some of the bondo would surround the damaged area, feathering in the new surface height. With the marker ink still on, and a wet rag handy, crank up the body grinder with the shrinking disc and rub the area. You vary the pressure according to how much you need to shrink. On the first pass I usually apply light pressure. The metal will quickly begin to rise and expand from the heat build-up. Remove the disc and wipe the area with a wet rag. With that operation you have started to shrink, stress relieve and further fine tune the outline of the low spots. You can now re-mark with ink, file and further tap out the low spots with the slapper and dolly. Some dents might require several cycles, but as you hone your technique you should be able to remove most dents in fewer cycles . At this stage an obvious high spot might have developed. You can easily remove it by rubbing the shrinking disc over it; it will heat to a blue condition in seconds, and then cool with the wet rag. After I'm satisfied that I can no longer effectively raise any remaining tiny low spots (depressions only a few thousands of an inch deep). I then install the very dull 120 grit 9" grinding disc and proceed to work the area with it. The grinding disc will level the area leaving a almost polished surface, it will heat the area quickly also, so cool it with a rag after you done grinding. If you have done everything correctly you should have a very smooth surface , that is stress free and in no need of bondo. If you practice these techniques on some old , damaged, and unimportant sheetmetal parts you will quickly hone your skill. On some areas of the XK Jaguars it is almost impossible to get a conventional dolly into the area; in those cases you have to be resourceful and fashion something that will snake into the damaged area, it will be effective as long as it resists the blows of the slapper causing the metal to rise. Regards, Wray E. Schelin ----------------------------------------------------------------------------------- Here are a few shots of the progression from the severely dented roof, to one that will need no more than two medium coats of hi-build primer to fill any minor flaws. ![]() In this next picture, it looks worse than it really is. In reality, the high spots need only slight shrinking to bring them down to the proper surface level. If I were to bring the entire area up to the point there were no low spots and all the marker were sanded off, it would take a considerable amount of shrinking to get the job done. As it is, the high spots are only a few thousandths of a inch high and lightly running the shrinking disc over the entire roof panel will quickly level it out. ![]() This is the result after a couple passes over the roof with the shrinking disk. It's pretty good at this point, but there are 3 or 4 small areas that need a little work yet. ![]() And here is the final product. If I had sanded it more, it would perhaps have shown better how straight and smooth this roof panel is, but I haven't got the time right now. The dark spots you see is where the shrinking disc run on the surface and discolored it a bit. All total, I have just under 3 hours repairing the dents, which covered the majority of this roof. Having spent years smearing body filler, I know it can't be 'fixed' any faster going that route. In fact, I can guarantee I would have spent at least twice that long using filler and perhaps much longer!!! ![]() Randy Ferguson Ferguson Coachbuilding (618) 544-2972 www.metalmeet.com |
|
#2
|
||||||
|
||||||
|
A master of your craft. Thanks to you and Wray for sharing.
|
|
#4
|
|||||
|
|||||
|
Im currently restoring a 69 porsche 911 and there are about 5 fist sized dents on the roof. this was a very good right up and i plan on following it. however, i cant seem to find the shrinking disk mentioned. of course its sunday night/ morning and im browsing online until i can make calls tomorrow.. any ideas where to find them?
|
|
#5
|
|||||
|
|||||
|
I make shrinking discs, and Wray started making them as well. There are rules? on this forum about posting links, so contact me directly if you are interested...I have several albums showing what you can do with one: ghiafab@msn.com
John |
|
#6
|
||||||
|
||||||
|
The one I have pictured is from John Kelly. He'll fix you up!
|
|
#8
|
|||||
|
|||||
|
Hey Randy take a look at this and give me a suggestion.. turns out there are alot more dings then i thought after doing the magic marker and blocking.
Thanks |
|
#9
|
||||||
|
||||||
|
Hi Beemdubya,
It looks bad, but if you follow the rules, you will get it totally remove and won't need any filler. It's very rewarding the first time you accomplish that!! Please take lots of pictures and keep us posted. I can't wait to see your results. I'll give you a little piece of advice that might make it seem not so overwhelming. Work the small spots first, until you have them brought up to the surrounding sruface level. Do just as Wray suggested in the tutorial and keep checking with the sanding block to monitor your progress. Before you know it, your confidence level will go through the roof and you'll know that there's nothing the metal can do to control you. You stay in complete control over the metal at all times. Have you ordered your shrinking disc yet?? On a side note, I'm looking for a good Porsche forum, particularly for the 356. Do you know of any?? If you have a list, please send me an e-mail with the url's rodbuilderandco@frsb.net Thank You. Randy Ferguson |
|
#10
|
|||||
|
|||||
|
Randy, a good porsche forum is hard to come by i havent found a decent one yet in fact i think i only found one and that is www.flat-6.net. im thinking most porsche owners dont really need to know how or what anything on there car does since most of them pay others to care for there cars(only my opinion).
as for the shrinking disk im gonna try a home made deal for now. i found a 9inch baking pan in my cabinet and its 18g. if i feel it doesnt work properly or im gonna be doing alot more of this i will opt to buy one. I should have some more pics in a couple days and im also going to take a little more of ur advice and try out this southern poly epoxy primer. Ill keep my pics coming. And since this is the first time im trying this i hope it will encourage other first timers to as well. Buddy M. |
|
#12
|
||||||
|
||||||
|
I am just starting the body work on my project and I am not a bodyman. I have several dings throughout my panel and REALLY did not want to use any filler. This was excellant information and has taken some of the "scarriness" out of trying to tackle this. Of course there's no substitute for experience but, one doesn't get it by sitting on the sidelines going "Oh, I don't know how to do that!"
Thanks! Jon |
|
#13
|
|||||
|
|||||
|
Hey Bob, I see your in south jersey. If your doing body work on a regular basis, it can never hurt to find a good Paintless dent repair technician. (hint hint)
Seriously though... A good dent tech can make you day go a whole lot easier. I am not talking about a big roof job like the original post, but when your doing a car and you have a pannel with a few small dings that you really don't want to have to get into the paint work on, we can fix it up pretty darned good, and it doesn't add much cost to the job. I do work with several body shops in my area. If they do some colision and there's a door with a few dings that will stand out after all the good work they have done, they will use me to clean it up, and everyone is happy! I even work with a limo company that has 100 limos and 2 bodyshops. Believe me, they love it when they can save time/money on ANY pannel. (ussually cost them under 100 bucks for me to clean up a few door dings) and the time/labor for them would be more even without the materials. |
|
#14
|
|||||
|
|||||
|
anybody make/have one of those slapper things?
I'd like to see a pciture of one. I'm trying to get the visual in my head. thanks for sharing Randy - good work on the roof there. -W |
|
#15
|
|||||
|
|||||
|
Quote:
Check out a company called Eastwood, I think I saw one there. Eastwood Co. calls it a slapping spoon #31222 sells for $24.99 Last edited by jcclark : 02-10-2005 at 11:03 AM. |
![]() |
Back to top |
| This discussion has been added to the Body - Exterior Discussions category of the Hotrodders Knowledge Base. |
| Thread Tools | Search this Thread |
|
|