Can anyone explain shrinking

Tonight I was shrinking some spots on a rough 32 shell .I was wondering If anyone can give some tips ,This is a torch in hand water and hammer dolly thread ,Just household items ,No shrinking discs ,

 

oh , a different type of shrinkage. i thought maybe you just got out of the pool

 

Man I just about feel outta my chair! I needed that good laugh, thanks!

 

I was thinking of a cold shower...but never mind...

R-

 

it's hard to shrink using just heat and wet rags on a item like a shell due to the thickness and compound curves. it takes a bit of actaull metal moving depending on what your looking at. i see isolating opposite sides of the area to be shrunk and tying to hammer and dolly towards the center, pushing the metal to the center from all sides along with the before mentioned heat shrinking

 

Just looking for any tips ,Also have spots on the 32 cab ,The shell I think is done I checked it with a straight edge and when I do the filler work Ill find out.Im new to this ,Metal shrinking that is.........

 

Invest in a shrinking disk, it will make your life easier.

 

As metal is heated it expands. By heating a small area that is surrounded by cold metal that does not expand, the heated area has no place to go but to bulge up. As you hammer the bulge down it compresses the molecules together and actually thickens the metal in that spot slightly. Then when you cool it with the water, it pulls the surrounding metal in as it contracts.

 

Have one over dads ,But he's on vacation ,.I dont feel like running over ....His house I dont have a key......Thanks Jim I guess I was doing it right ,I tried heating the metal and thought it would pull in and when wetting it I thought That was to control how far .....Then I pulled out the hammer and dollie...

 

You have to work small areas at a time. Too often guys try and shrink a big area all at once and get no where but frustrated. Also times 2 on a shrinking disk way easier to control than a torch.

 

excellent.
thank you.​

 

Its hard to say with out seeing what you are working on is the piece easy to pop in and out and when it is out you feal you need to shrink it to get the right hight? or is the piece really stretched out and is making creases when you are dollying it back in. there are different techniques to get these different problems solved.

 

I've been thinking about trying the shrinking disk tool but for now I use the tried and true hammer and dolly with torch method. You do need to work small areas around the perimeter of a big dent and work toward the center. Slow and steady.

I suggest you buy a little red book called "The Key to Metal Bumping" that is available from a lot of places including Speedway. It was written long ago before Bondo and takes you step by step through the process of straightening dents and other body work. With a few good hammers and different dolly's you will be amazed at what you can bring back to life.

 

Hey John,

Hot Shrinking, as this operation is called, is best made only after all the bumping of any high or low metal has been completed. Once you've figgered that what you have is, in fact, a stretched area, and not just an area held under tension/pressure by surrounding damage, you can correct it as follows: Choose a dolly or s**** that best matches the crown of the panel you're trying to repair. A large faced, low crowned bumping hammer or a ******* is a good match for your dolly/s****. Now bump the damaged area with the dolly and watch how the area moves, and press about the area with your fingers. If you find a high/hard area in the middle of the damage, that's where your first shrink should land. With a #2 torch tip produce a netural flame, and heat a spot no bigger than a dime. Small shrinks are better than larger ones. Put down the torch, and hit the spot from behind with the dolly whyle you hit the area at 8 o clock, 2 0clock, 10 o clock, and 4 oclock etc. until you've covered the heated spot.Try for slapping blows, not like you were driving a nail, but pushing the area beneith the hammer into the center of the heated spot. Your last blow should be in the center of the heated spot. With a wet rag, swipe across the area until you can touch the area with your hand.
It will probably take several/many shrinks to repair a badly damaged panel.
This ain't rocket science, but you have to be able to "read'' a panel, and plan your corrective action accordingly. An over shrunk panel is more work to correct, than an un worked damaged one.

" The ice cream truck in his neighborhood plays Helter-Skelter "

 

I'm not going to "embed" the video for it will surely(and don't call me Shirley) get deleted or the thread closed..

http://www.youtube.com/watch?v=1cUNNKzj_Nc

 

metalmeet.com
this place and its links will teach you a lot.

 

http://chevy.oldcarmanualproject.com/index.htm This is a method in a 1941 factory Chevrolet manual. Guess it might work on a Ford.

 

Not going to try to explain how but this will give you some idea as to how many (with a torch, hammer and dolly and quench) and the size of the spots. This was done to remove the stock 'belly' on Merc. skirts to mount them 'flush'.

 

I shouldnt tell you this ,But I scored a 32 shell original on the bay for 190 .00 I bought it and saw the bad areas ,This shell was peiced back together and lower chin was bent slightly ,I fixed the lower chin by pie cutting ,The welder did a descent job .The sides that were peiced together are warped from the other guy ,I decided to shrink with the mapp gas torch ,I never did it before ,But I understand the basics of metal.Just never shrunk ,Being a bodyman as a hobby ,I can say I do a damn nice job ,I try only to do panels to black perfection ,Unless its a new pos.After I shrunk I checked with a straight edge ,It will be fine ,My 32 truck has some spots that need to be shrunk also ,Ill try the disc on that ,

 

One big advantage to a shrinking disc is that if the metal is still somewhat irregular it will shrink the high spots helping to smooth the panel.

 

Sorry had to answer the phone. most of the time the panel doesn't need to be shrunk at all, it just needs a little work in another spot to make the hole panel move or as I say tight n up.I've even walked dents all the way to the edge of a panel to get rid of it. I haven't used a shrinking wheel in my 15 years of body work but I have used shrinking hammers. don't like them but some times they come in handy. these hammers look like a meat tenderizer with perforations on the head when you hit the metal it squeezes the metal tighter together to shrink the spot. this is only going to work in some situations. if it is so stretched out it is forming folds as you try to work the spot it might be better to get it as close as you can than cut the panel and work it some more than weld the slice.if the panel is rippling or the dent keeps moving along the panel you might need to re***ess the dent and look else ware for the culprit of the seeming high spot like I said in the beginning. If I was there I could tell you exactly where you need to go but all I can do is give techniques it took a wile for me to realize what some of the old farts were trying to show me but you have to play with it and watch the metal move. I still come across situations were I say O so thats what that old fart was trying to tell me.

 

Whooooooaaaaaaa...hold on there for a moment!
You said someone pieced the stuff together, I'm guessing that means welding.
Now you have warpage, from the welding???
OK, that doens't immediately mean you need to shrink anything, more likely you need to stretch the welded seams to REMOVE shrinking! The heat of the welding process shrinks the metal, so to correct it, you need to slowly, carefully stretch the metal back to it's original shape. Do a search on hammerwelding, to get an idea of what to do. If you try to shrink this, it'll make a bigger mess than you have now!
Doing this on MIG welds is a bit tough to do, but possible. Again, read up on the technique.
I usually grind bad welds down and heat them a little to hammer them back, if I work on some unknown welds. Or, gas or TIG weld the MIG beads to make them flatter and more compliant.

 

this is my friend doin a model A fender. pretty self explanatory.

http://s11.photobucket.com/albums/a175/TheGraves666CC/Bobs Model A/?action=view&current=HPIM2128.flv

http://s11.photobucket.com/albums/a175/TheGraves666CC/Bobs Model A/?action=view&current=HPIM2131.flv

 

jleblanc31, can we talk you into doing a tech article on shrinking? You know, with some pics and examples and explain how to see the metal move. This is the kind of info that is p***ed down from old bodymen that rarly makes its way into print. Thanks, oj

 

Hammer and dolly is my choice most of the time. Kind of hard to explain as I'm not the best teacher. But I highly recommend "The Key to Metal-Bumping" by Frank Sargent
It does a much better job than I could.

 

Pimpin Paint explained it really well. I would just add that you do not necessarily have to use a hammer and dolly, just heat. If the metal is high but smooth, the torch will shrink the high spot without immediate hammer and dolly work. Try heating just until the metal swells a little, no need for a color change in the metal. If you see steam when you quench you have reached the right temperature for shrinking. My youtube videos below (Custom Metal Bodywork parts 8-12) show this type of work done with a shrinking disc.. same concept.

John

 

Wow that is some nice work there.

 

36-3window-
"I was in the pool!" LOL..one of the best ever.
http://www.youtube.com/watch?v=1cUNNKzj_Nc&feature=related

 

Shrinking Mild Steel can be done Hot and Cold. I use about 5 different ways of shrinking.

I try cold shrinking first, using a hand held shot bag and a plastic hammer. You'll find the shot bag will allow the metal to shrink or go somewhere. Use the same technique as hot shrinking were you hammer from the outside of the high spot hammering towards the centre and then hammer down the centre. You'll be suprised how much metal you can shrink this way.

To Heat shrink us an Oxy/actylene torch set to a neutral flame. Heat the high spot to the size of a dime (Max) hammer the metal around the hot spot towards the centre and then hammer down the centre and cool the spot with a wet cloth. When hammering, lightly support the area with a Dolly of the same conture.

These are the most basic ways to shrink the metal.

Hope it helps: The Old Tinbasher

 

Thanks guys I learned alot from just reading what you had to say ,Shrinking is a lost art ,Im 42 and No one ever showed or taught me.Thanks and keep the thread rolling......