well i put this little problem in the bodywork section, but ill put it here too....ive been gone for the summer, n when it comes time to go back to the 53, im havin problems with it before i can even blast it

ok, this problem is holding me from blasting and starting to get the ball rolling on actually painting my 53.....the metal on one part of the top of the cab is stretched out in a little spot and has formed a "goose egg" on top of the cab, almost like the goose egg you get on your head when you start coming up before your head is actually out from under the pickup after workin on it...... my question is, HOW DO I GET THE GOOSE EGG TO GO AWAY????????
very disgruntled,
darrell

 

kinda like the oil-can-effect? tricky, but if that's what it is then applying heat with a torch to make it glow and then hit it with a body hammer with the dolly holding equal pressure underneath will shrink the bulge, and then apply a wet cloth to cool it. Should make it go away, if not, then the "chasing-the-shrink" game has begun. If this is new, then I'd recommend taking a scrap piece of metal and bash it with a big hammer to stretch the metal, and then try the techniques explained here to level the hammer blows, practicing will gain ya confidence. Better to do it right rather than ruining some good vintage metal. good luck. Blasting may heat the cab up too which will cause bumps, so beware.

 

sounds good....ill try it in the morning.... im gettin anxious to get back into it and get it ON THE ROAD..... but painting comes first....

 

To shrink the metal: First have a helper or a rest where you can put the torch down without shutting it off. Using a small hot flame on your torch, heat a spot in the center of the egg about the size of a dime until the metal turns cherry and you see it bulge up. Hand the torch off and immediately place a dolly under the spot and TAP it down even with the surrounding metal with a body hammer with a slightly crowned face while still red. DON'T hit it hard or you'll just stretch the metal back out! Wait until the metal air cools enough to touch and check the progress. If it needs more shrinking, do another spot at least a couple inches away. DON'T overlap your shrinks or try to shrink the same spot twice, there needs to be cool unmolested metal around the heated spot to work. Old school method would quench the metal with a wet rag, DON'T do it! Let the metal air cool. You'll be amazed at how much shrinking one little spot can do.

 

Ax, why air cool rather than quench? Quenching with a wet rag is what I've seen for years, what's your take on this?

 

Per Ron Covell: don't quench since it hardens the metal locally making finishing more difficult, and increasing cracking risk. He shows quenching in his video, but there's a big warning overlayed NOT to quench.

 

Gee, I just bought me one of them fancy shrinking hammers with the serrated face. I figgered that thing would work great on this sort of problem.

Given the responses so far, I'm worried I now have another useless toy to add to my collection. With the searrated face, I can't even drive nails with this one.

 

Shrinking hammers and shrinking disks work on low profile stretched areas such as where you have done some work to take out a dent and have a few "bubbles" that are proud of the finished surface to deal with. Torch shrinking does a LOT of shrinking and is best used where a large stretch has taken place or you have one of the "oilcan" situations where the dent pops in and out when you push or hammer on it from one side to the other. I ran into that situation on my firewall where the fill panel shrunk along the welds popping out the center in a very low pillow shape. It looked relatively flat until I put a straight edge across it. Bumping it in the center would just pop it in, and then pushing from the inside it would pop it out again. Had I taken the easy way out and filled along the seams with bondo, when I bolted on the mastercylinder it would have pulled in the oil can and cracked or popped the bondo off or left the firewall all wavy. I ended up doing 3 torch shrinks in a vertical line in the center of the panel which pulled it flat. Before you decide if you need to shrink a panel or dent you need to decide if stretching has taken place by analyzing the area in question relative to the panel's finished shape: Picture a soft metal bowl upside down. If you were to very carefully cut a profile template of that bowl, the edge of the template would be the bowl's intended shape in profile. Now if you pushed on the bowl with your hand hard enough and the bowl was soft enough you'd cause a dent, i.e. the bowl's profile would be distorted, but no metal stretch has taken place. You could take out that dent by hammering it "off dolly" with light taps of a convex faced hammer or better yet nylon mallet, working slowly around from the edge of the dent to the center so that the metal would be returned to it's original profile. Now imagine instead of this method you tried to take the dent out the "cootiebobber" way and wacked away at it with the round end of a ballpein hammer until the dent was pushed back out somewhat near where the metal used to be, but now the area looks like a bag of walnuts! That appearance is due to the fact that the ballpein concentrated a lot of force into a very small area and caused the metal to stretch at each hammer blow. You may be able to smooth out all those bubbles, but you would have more metal than you originally started with, so the area of the original dent would now bulge out higher than the original profile and not matter what you do it will never be able to be brought back to the right shape unless you shrink the metal back to it's original size. (Deliberately stretching the metal in the center of a panel and then working the surface smooth is the basis for creating a compound curve out of a flat sheet.)
If the bulge is just slight you could shrink the area with a shrinking hammer, if it's still has a lot of small bumps, you might use a shrinking disk to shrink down all the high spots. If there's a fair sized smooth bulge you might need to get out the torch and heat shrink it.

 

ok, well the egg is probably 2-3 inches across....how does the dime size heating method work then??

 

how high above the proper profile? If more than 1/8" you'll need to heat shrink it with the torch method, do your first shrink at the highest point, don't hammer hard enough to dent the center concaved. If one shrink doesn't do it, or the strech is more than 1/4" do three shrinks in a 12, 4 ,8 o'clock pattern leaving ~ 1" of unheated material between the heated spots, and allowing each shrink to cool enough to comfortably rest your hand on it between shrinks. If that isn't enough shrinking to bring it down do another circle of 3 shrinks between the first 3 and in in an inch bigger circle. I can't imagine a stretch high enough to need even the last 3 shrinks that didn't tear the metal.

 

aww, heck, i guess its not all that much, but enough to make it look retarded when u stand in front of it....1/4 inch maybe?? i have no idea.... somewhere between 1/4 and 1/2 i would have to say

 

Easy to check Darrell - put a straight edge across the dimple and measure down to the deepest point. If it's popped out, you can measure on the inside or estimate by holding a straight edge across the highest point, parallel to the base metal. Then measure down from the straight edge to the base metal. You'll kinda have to guesstimate for a curved section.

 

If on a curve say the top of a fender, use a giveaway yardstick from the lumber yard and press down the ends until the yardstick is tight to the curve as close to the dent as possible that's on unmangled metal. look at it at eye level to estimate how high the bump is the yardstick is ~ 3/16" thick. If the stretch is dented into the panel, knock it up first or work from the other side of the panel, always shrink from the high side.

 

My brothe decided to take down a metal streetlight pole with the rear bumper of his 66 LTD on the expressway one night (don't ask!) caving it in nearly to the rear window and landing it on the roof. We found a good donor with the opposite problem and decided to cut it at the windshield header and through the front doors and replace the entire rear clip. Only problem was when the yard help cut the donor apart and loaded it onto the truck they hooked a towtruck boom hook onto the header to pick it up and put a 1" high egg right in the center of the roof! We were able to heat shrink that stretch out with 4 or 5 shrinks.

 

AXracer, great overview of heat shrinking. Thanks.