The Stovebolt Site Forums The Shop Area Paint and Body Shop Help-High Spot from Hell

Hi Everyone,

There is a high spot on my rear fender about 4" in diameter. There might be some ridges in it. When I lay a straight edge accross it, there is a gap on either side of almost a quarter inch. Moving the sraight edge fore & aft or checking the other fender shows I shouldn't have this gap. I beat it in, but its also oil-canning, so I'm hesitant to leave it in like that. I have thought about just cutting out the meatal and welding in a new piece or cutting out a small strip. Is it possible to get this down with hammer & dollies? How?

Thanks,

A "shrinking hammer"? It looks like a meat tenderizer. I've seen people use them,but never done it myself.
Might want to ask around before attempting.
Marty

Sounds like you have a high spot Eric, (redundant), that means you have to much metal in that area and you need to shrink it. Hammeing on it with a dolly only thins the metal out and stretches it out more. If it is a small area (silver dollar) you may be able to apply heat with a torch and quench it with a wet rag, try that a few times and it may bring it back. If it shrinks back to far then you can dolly it out smooth. If its a very small area (fingernail) you may be able to use a dolly that is slightly concave and tap the high spot down into it. Don't beat on it, it only takes a little pressure to reshape a thin section so just tap, tap, tap.
If its a large area and it sounds like it is if its oil canning, then you might concider a shrinking disc. They are cheap and work by heating up the metal by friction. Down side is it takes a little practice to get the feel for it. Denny Graham
Sandwich, IL

By gettin the worst of it close by supporting it from underneath with a round dolly and using the shrinking hammer directly over the dolly you will be able to shrink it somewhat. Once you have made a little progress take a propane torch and get a small area about the size of a quarter hot. Use the wet rag method as stated by denny. This will tighten the metal and allow you to work it again and again til you get it as good as you can. The disc is a good idea but if you've never done it you can burn thru the metal. If you get too frustrated and have had you're fill it is easier to smooth out a low spot (THUMP!!!!) Welding a piece in would create a nightmare for you since the heat would distort the heck out of it.

Thanks for replys. Will a propoane torch get the metal hot enough or does it need to be red?

I agree with the propane torch and wet rag. I've seen even higher spots shrunk by running a quick MIG welder bead over the spot and hit with a wet cloth. Cutting would be my last resort. I think you'll see results with the propane torch... might take a dozen attempts as it will shrink a little at a time. No need to get cherry red, just real hot so the water sizzles when hit with the rag.

Lee

Eric,
Dont believe in shrinking hammers. They do next to nothing but destroy the metal.
If you heat shrink metal all you need to do is heat the metal enough so that when water is applied it steams.
Cherry red or blue is way to hot!!

Before you start shrinking metal, make sure you have the surrounding metal back in place. If your panel feels like a bag of walnuts then its NOT ready for shrinking. The metal should be as close originaly contours as possible.

A shrinking disc is the easiest and safest method of shrinking. A shrinking disc ONLY shrinks whats needs to be shrunk. A torch will shrink anything in its path including metal that doesnt need to be shrunk.

If you look throu my link in the sig you will find several metal finishing albums that show how to correct metal damage using nothing but hammers/dollies and a shrinking disc...Eric

Was hopin you'd join in Eric E, I picked up a bunch of ideas from you site, thanks.
And the other Eric from Kokomo, check out Eric E's site there is a ton of interesting metal working tips there.
Denny Graham
Sandwich, IL

Well I worked on it the other night with a torch and squirt bottle & hammer & dolly. I didn't get it very hot, just enough usually to steam the water. After 30 or 40 minutes I called it a night without feeling like I made a difference. I'm wondering if the metal could be "work hardened" and need to be annealed or something?

I use a squirt bottle with a touch of liquid soap added. The soap allows you feel the metal better.

When you torch shrink you will see the metal start to raise, making a "bubble" in the metal.
Once this bubble starts put down the torch and grab a hammer and dolly. If you are not seeing some type of metal raising up then get the metal hotter.
You will want to use the hammer OFF dolly method, otherwise you will stretch the area you are trying to shrink.
http://www.imagestation.com/picture/sraid225/pc358365c47a5b1e8d9ce6a72452beb94/ea387981.jpg

Place the dolly on the backside of the bubble on the pretimeter(sp?) then hammer the down the bubble.
Work from the outside inward in a spiril motion, this will trap the bubble from escaping and shrink the metal. Once you have hammered down the "bubble" cool it with water...Eric

P.S just remember the ONLY spot that needs to be shrunk is the high spot. Do not shrink anything but the high spot.

Once again, Eric is the voice of experience and I would take his advice. Might not hurt to go out to the junkyard and pick up an old fender to practice on so you don't do any further damage to yours. This is a difficult skill to learn and many of the body men out there today live in a bolt on world and aren't capable of this kind of work.
When you gonna get those Vidios finishe EE, they should be very popular.
Denny Graham
Sandwich, IL

Every time you strike metal enough to leave a dent you have stretched the metal. Every time you strike metal with a "hammer on dolly" blow you have stretched the metal. What you end up with is the "oil can" you describe. What we used to do to shrink stretched metal is to heat a nickle size spot in the stretched area to cherry red (no, it's not too hot) using an acetylene torch, then placing the dolly directly under the red spot, hammer the metal around the red spot toward and into the red spot then quench with a wet rag. Hammer all the way around the red spot each time. Don't hammer hard, the metal will move fairly easily. It takes practice to do this right. Repeat as necessary to remove the complete stretched area. Sometimes you will shrink it too much and will have to do some hammer on dolly to stretch the metal back out. While I did a ton of shrinking using an acetylene torch I never did it using a propane torch as noted above. It may work OK but be careful of putting too much heat into the panel. If the spot doesn't turn cherry red in two-three seconds you'll need a hotter torch. I know that sounds funny but you want to get the spot you're shrinking hot quickly so you can shrink & quench it quickly so that the heat doesn't have time to migrate to the rest of the panel. If you overheat the panel you can end up with a nighmare of warped metal. I would strongly recommend practicing this with an old panel you have laying around before attempting this on your ride. You can ruin a good panel doing it wrong. Another tip is to wear lightweight cotton gloves while working out a dent. They protect your hands from the heat and sharp edges PLUS they make it much easier to feel imperfections in the metal. When feeling for imperfections always run your hand over the work lengthwise in a sanding motion rather than a side to side motion. You'll get a much better read of the panel doing it that way.

Excellent point Tiny!

Eric, this might be the time you start looking into a shrinking disc. If you have more metal work to do the disc will pay for itself the first time you use it.
One of the best metal shapers in the USA has his disc mounted on a 20 dollar harbor freight grinder.
So for 60 bucks you can have a tool IMO is idiot proof, has a small learning curve and will work far superior to a torch...Eric

try a weed burner and a hammer and dolly and work the metal i had a 55 chevy once someone had beat on the back panal played with it many houres just did small areas of heating and tapping watched what it did it did come back but it took me hours something i never want to do again when i did it i held the dolly and tapped around it not on it to lower the metal inward

Lots of advise here. Shrinking is something of a lost art to the older body guys. You can drive youself nuts with this and end up making a bigger mess real easy. Takes lots of practice. The idea is to work the metal around the small spot you heated genly with hammer and dolly as the metal cools. It will pull what you "stretch" working around the problem spot and make it "tighter."

Well, first thanks everyone for the advise. I have the high spot "down". I used a torch. It's not perfect yet, but it's much better. I probably will get a shrinking disc and a decent 7" grinder. The HF one runs 8,000 rpm and all the disc and backing plates are rated for 6,000.

Tiny does it the way I learned.

mayby take it to a body man just for the one dent or !

Tiny's advice is definitely the right way to do it.
Takes some patience but gets the oil can out without removin any metal.

I fixed a high spot similar to this one time by cutting an "X" in the bump with a cutting wheel, then hammering it down flat, then mig welding the "X" slowly with a series of small tacks. The weld will shrink as it cools which will pull the metal tight. It wasn't perfect but it was good enough for an amature like me. After putting a skim coat of filler and sanding, you couldn't see it. Just a thought.......

tiny is right on ! i might add that you use a light body hammer . i learned the art of metal finishing from my father over 35 yrs. ago . Mark