Metalwork help please..or..Damn! I made a valley

I'm new at this kind of metalwork, but I'm learning thanks to HAMB!

'53 Chevy - welding the hood halves together, got a little to hot in one spot and made a, oilcan hill. Did a little shrinking - dime size heat spot with a torch, a little hammer/dolly. Got rid of the oil can and ended up with a valley about 3" long, 2" wide.

Now, I've learned that my oilcan hill was caused by the metal stretching, but is my valley caused by over shrinking?

Thanks for any and all advice.

Carl

 

the weld shrinks the metal in the Heat Affected Zone or HAZ.
If it got streched, It was fron the Hammer and dolly work that you may have done.

An oilcan situation can happen in a bunch of ways, but two real common ways is to stretch the middle of a area or shirnking the edges of an area.

sounds like the area of the valley needs to be streched Or Unshrunk back to a relaxed state

 

You have a problem that's not that easy to resolve if you have limited experience working with sheet metal. The valley is not really any different than the area you've already heat shrunk...It's just "down" instead of "up"... the sheet metal does'nt know one from the other.

If you were successful in shrinking the first area, you should be able to shrink this one as well....Just stay away from pounding the metal with a hammer and dolly any more vigorously than necessarily..

It's a good rule of thumb to keep in mind when using a hammer/dolly...Every time you hit a piece of sheet metal backed by a solid object you reduce the thickness of the sheet metal somewhat....even though that might be a microscopic amount it's still thinner...And that extra metal has to go somewhere.

Hammer/dolly work is an art form in itself and takes considerable practice and forethought to use effectively.

Peaking a hood used to be done by welding the front and rear sections about 12" from the end. Tacking the remainder at intervals then filling the joint with lead, which also served to help bond the two hood halve together.

Now...There are excellent panel adhesives available that have the bonding strength necessary to hold hood halves together permanently. If I were to take on the task I think I'd bond the hood together, weld the ends and replace the original rivets with nuts and bolts along the inside flange.

 

hummm, you sure haveing a time of it aint you kid? atleast you got pluck and are sticking with it... normally when I was heat shrinking I was heating a spot (dime size or so) to an orange glow and then quickly quenching it with a wet rag.. heating it frees up the molacules and relaxes the metal- the quench then snaps the molacules into alinement and tightens the metal back up. and it just takes an eye to determine where you need to do this. but spare your hood for awhile- go to a salvage yard and get a hood and recreate you valley... then practice practice practice

 

What I do in a case like this (it has worked very well for me over the years) is to cut a slot in the centre of the problem area with a cut off disc. (Cut off discs come in various thicknesses and I judge the thickness to use by how much I need to pull the metal in). After the slot is cut it relieves the tension in the metal, gives the stretched metal somewhere to go and now allows you to hammer and dolly the area to proper shape. Once your happy with it now weld up the slot moving around of course so you don't produce the same problem you started out with. On really bad areas it may be necessary to cut an "X" in the metal instead of just a slot. I have used this method for years and found it to be the quickest and most painless.

 

when you welded up the seam it shrank. did you hammer and dolly to stretch it back to shape and go to far?

if you welded it, then started shrinking the other areas to fix it, you have gone the wrong way. you should be stretching the haz areas not shrinking in places that saw no heat.

weld, hammer dolly, weld hammer dolly. once its hammered roughly back to shape then you can start checking for high spots that need shrinking.

you should not be heating anything cherry red hot, shrinking can be done without changing the color of the metal. heating it cherry red and quenching it may harden the material and make it much more difficult to work.

 

I'd think it would be hard to weld hammer dollie in this instance, as there is a double flange in the middle of that hood.

 

ok, but shrinking something that is already shrunk isnt going to fix it. You should find a way to stretch it back.

pics would help.

When I peak a hood, I make a new strip for the center, peak it on the brake, or run it thru the bead roller, use shrinker stretcher to shape it to the hood, build a frame work to hold the hood and cut the center of the hood to fit the patch.

weld in, hammer and dolly it back to shape. doing it this way will usually leave it wide open for any needed hammering.

 

First - thanks to all of you, amazing how much you guys know.

I will dig into each of your responses in depth when I get home and I'm looking at the issue.

To start with, the car is my first mild custom, it's a four door for my family and for from mint condition. Im not planning on peaking the hood, just removing the factory strip and badging and welding to two together. The hood had a few bulges of it's own that I needed to deal with so I wasn't that worried about running into issues.

Initially I wanted to gas weld the halve to lesson my dependency on my MIG. Got some great advice here, practiced and gave it a shot - an made my hill. Then I switched to MIG (for now) taking my time I did a pretty good job of welding up the hood. Then I attacked those old lumps and shrunk them down nicely. All that is left is this valley.

With your info, I'm sure I'll make it right!! The H.A.M.B. RULES!!

Again, this will never be a show car, but I know it'll be a fun car.

 

IMHO, so far, I would have to think this would work the best for you.. as your last thread was about gas welding- I will take a leap and ***ume you are gas welding this.. just remember that puts out alota heat, specially if you are new and slow at it. And heat = warp

good- go with the mig-- may need to get out the pick hammer to

 

Did you weld over the hill with same method? sounds like what was happening is the welded area was shrinking and that created the hill. (Think about pulling a loose thread out of a ribbon)

 

I did the same thing to my son's 54 chevy sedan when I we put it together about 9 years ago. I ended up getting some 3/4" box tubeing and welding it down the center on the bottom side of the hood. This gave me some support so I could bend the metal and it would stay. These hoods are very flimzy and we hard time with it. I know this was not the correct way to fix the problem but it was just the way we did it. Oh, I forgot it helps th cuss at it and throw stuff around.

 

yeah most important part, well that and remembering to throw things away from **** you will have to fix later if you bounce a wrench off it.