metal shapping advice needed, specifically how to shrink.. Options

[brant]

Hello all and John if your reading along today.
I've been doing some fender slicing and welding...
of course lots of pounding also...

specifically, I need some technique advice.
So I've got a spot that I want to shrink or tighten extra metal in.

I know John sells the shrinking disks which I'm considering, ... but in the interm, what is the old fashioned shrinking technique.

I know to heat the area with a torch.. but then do I cool it rapidly with water or something... or do I let it cool slowly to get the most shrink out of it?

hope this makes since
brant

[ArtechnikA]

I know to heat the area with a torch.. but then do I cool it rapidly with water or something... or do I let it cool slowly to get the most shrink out of it?

quench quickly to shrink.

the goal is to get the metal to contract before it has a chance to lose its plasticity from the heat. if it cools slowly, it will contract but it will not be permanent.

i don't know anything about the shrinking disks but i've heard about them - i'd love a pointer to further information.

there are also shrinking hammers and dollies that are covered with little pyramid points - like a ginger grater. i'd think these would work best on hot - or at least annealed - metal - but i don't have any first-hand experience in their use (although i do have a set in my bodywork toolbox...).

Ron Fournier's metalworking book is excellent ...

[brant]

thanks rich

[rhodyguy]

i've seen john's disc. could be on my christmas list. at least your garage won't be full of smoke and you don't need a fire extingisher handy. you would be supporting a member's efforts also. help keep a brother in beans and rice.

kevin

[ArtechnikA]

i've seen john's disc.

i haven't, but i'd like to. can you post some contact information or a picture or a website or something?
can't support him if i can't get hold of the guy or the product...

[rhodyguy]

try www.ghiaspecialties.com. search for john kelly. he is at shoptalkforums on occation. this item should be in the parts, products forum.

kevin

[John Kelly]

Thanks guys! Here is my album page. It has several albums on shrinking discs:

http://allshops.org/cgi-bin/community/comm...d=9990093068868

If you going to torch shrink, heat only until the metal turns straw colored or maybe blue, not red. If the metal does turn red, do not quench, as it will get work-hardened. Heat small spots, let them cool (or quench, hammer and dolly the area to get smooth. Repeat as necessary. Not easy to do without making a mess.

Stay away from shrinking hammers. They make a lot of unnecessary marks, and don't work very well.

You might try a wornout sanding disc to heat the surface without removing much metal, then quench. Much more controlable than torch shrinking.

Here is an article that might help:

http://www.type2.com/library/body/wlsh.htm

Before shrinking, make sure that you actually need to. If you have done a lot of welding you have already shrunk the metal, and will need to stretch the weld area. Any pictures?

John www.ghiaspecialties.com

[brant]

John,

thanks for the advice. Sorry I don't have a digital camera (how many times will I say that!)

the area I want to shrink is a 914 front fender side turn signal area. I mig welded in a small round disc to fill the hole. I hammered and dollied it for an hour. I think in all of my hammer work I stretched the metal, because now the area is bowed/bubbled out in a 6inch area. I can flex it in, causing a low spot, or flex it out causing a high bubble.

This brings up a question for me. When I first welded this hole, should I have used water, or a cooling method. obviously I didn't, and let it cool slowly which I thought would cause less shrink.

So now, I will heat a very small area, and use a cooling method to try and shrink it... then re- hammer/dolly it.

is the shrinking disc worth it for such a small 1 time use?

thanks for your time John.
brant

[John Kelly]

Hi Brant,

If you are seeking perfection a shrinking disc might be worth it for one time use, but I wouldn't recommend it.

I never use water unless I'm using the shrinking disc. Especially when welding as the area is shrinking enough already and will get more difficult to hammer and dolly.

Did you grind the both sides of the weld? This is usually necessary on a mig-welded panel before using a hammer and dolly.

Try the back side of a sanding disc (installed backwards on your backup pad )against the surface, then quench. I don't know whether or not this will work. If the metal steams when quenched, you are shrinking.

John www.ghiaspecialties.com

[J P Stein]

Sounds like you gots a gud start on some flares (IMG:style_emoticons/default/laugh.gif) .....keep on (IMG:style_emoticons/default/smash.gif) (IMG:style_emoticons/default/beer.gif) (IMG:style_emoticons/default/smash.gif) (IMG:style_emoticons/default/beer.gif) (IMG:style_emoticons/default/smash.gif)

[brant]

John,

yeah, I ground down both sides of the weld with an electric grinder and a sanding disc prior to hammer/dolly.

The high (or low) bulge is probably 1/4 of an inch tall...
not a huge amount. I'm not expecting miracles and huge amounts of shrinking... just a lil' bit.

thanks for the tips on the reversed sanding disc.

JP... You should see the back fenders... I slit the 1st car and did all metal and this time I'm slitting in a different way and doing all metal also...

b

[J P Stein]

JP... You should see the back fenders...
b

Yes I should.
Where's the freakin' pics, damnit? (IMG:style_emoticons/default/laugh.gif)

I'm always lookin' for ideas to steal. I don't like the GT flares, I don't like mine....I like Johns full pooch smooth bulge jobbies, but I need wheel well width of about 11 inches...maybe 10 will do. The rear is the problem area.....humm...just like my own body, go figure. (IMG:style_emoticons/default/laugh.gif)

[tdgray]

QUOTE]This brings up a question for me. When I first welded this hole, should I have used water, or a cooling method. obviously I didn't, and let it cool slowly which I thought would cause less shrink.[/QUOTE]

Not sure if this will help in future but just my .02 I did my own welding on my MGA, it was my first attempt. I was really worried about warping the panels especially in the curved areas of the fenders. I used a special welding putty (jelly) that contracts the heat away from the panel. Got it where I used to work but I am sure that you can find it any PBE supply store.

Todd
1960 MGA
1973 914 1.7L (finding more rust holes everyday)

[John Kelly]

Hi Todd,

Welding always shrinks, so that putty does not have much effect. It may keep the heat from getting outside of it's borders, but that is not usually necessary. You can do the same thing by welding very slowly....which with mig is a good idea anyway. You still have shrinkage to take care of either way.

Hi JP,

How much room do you need? Are you measuring from the inner bulkhead out to the fender lip? I've got about 11" on Zach's, and could go further, although I think it would start to look out of proportion. Done a fair amount of work since you last saw the car. The flares are more full in the upper regions.

John www.ghiaspecialties.com

[brant]

John,

since you have a digital camera...
can we see any update pictures on Zach's?

I'm shooting for more room in the upper regions on this car since I'll be running it pretty low with 60/series (required by rule) tires.

brant

[John Kelly]

Hi Brant,

Right now the fender I'm almost finished with has ink all over it as part of the metal finishing process for the video. When I've got it back to shiny metal, I'll post an update...probably next week sometime.

This video stuff is harder than I thought, really have to make sure to get a lot of information condensed down to where it will fit and still make sense.

Zach and I are pretty bored with the project by now...just have to keep slogging. At least I get to wield a hammer...he has to just sit there.

John www.ghiaspecialties.com

[redshift]

I like Johns full pooch smooth bulge jobbies, but I need wheel well width of about 11 inches...maybe 10 will do. The rear is the problem area.....humm...just like my own body, go figure. (IMG:style_emoticons/default/laugh.gif)

Feed your car pizza, and dont' drive it for a month.


M