1930 Chevrolet Sedan Project

Another Update.Started with beat up fenders and tank cover progressed or regressed to warped and stretched metal and ended up with close to a acceptable result.Anybody use shrinking discs and did they work,looking for alternate method than torch and peening.Thanks.Mounted the 33-34 Taillight and stands yesterday.




 
Yes, and yes. I use a shrinking disc all the time, and yes they certainly do work. I get asked this question quite often. I'm not sure why there is so much doubt about whether they work or not.
If you are reasonably proficient with a hammer and dolly, to get all the highs and lows out of a panel, the shrinking disc is the tool that makes all the difference in the end result. There will almost, ( but not always), be some stretching from collision damage, and the resulting hammer work to get it back straight again.

A torch definitely works, and probably works best if you have some extremely stretched areas. The biggest problem with the torch is that once you get it down to the panel to heat up a spot the size of a dime, there will be heat everywhere around that spot, which could easily cause more damage than the original intent.

The shrinking disc, on the other hand, if used properly, only hits the high spots, leaving the low spots untouched. You only want to use it for a few seconds, lets say, 10 seconds or so, then quench with a wet rag. If you keep going over the panel with the shrinking disc, over and over, the heat will eventually travel from the high spots into the low spots as well, sort of defeating the purpose.

If you go to youtube, and type in ForWray, a guy did a video on it. It doesn't show him using the disc, but what it does show is a hood that a shrinking disc would work excellently on. On that hood, you can see the "mottled" look of the highs and lows in the sheet metal. If you put the shrinking disc totally flat on that surface, and run it back and forth over the surface, it will hit all the high spots, without heating up the low spots, as long as you don't run it too long. That will still need several tries to get it down flat, but it definitely works. It isn't a case of just putting the shrinking disc on the surface and run it for ten seconds, then quench it, and expect it to be flat. You have to work at it, sand it to find where the highest spots are, then do it again. Once you have it, I doubt you will use a torch again. It is very satisfying to level a surface that used to look like the surface of the moon.

That type of surface is what a shrinking disc is excellent at levelling. And I think it is way, way easier than filling all those low spots with bondo, and then trying to sand it flat again.

The shrinking disc will not take out a sharp crease. You need to use a hammer and dolly to take it out so that it is a rounded over high spot, then shrink it down.

Also, if you have an extremely stretched area, then go ahead and use a torch to shrink down the high spots, then finish with a shrinking disc. The torch will take the extreme spots down, and the shrinking disc would probably do it as well, but you might be there for a couple days doing it. Most repairs don't need a torch to repair them. If they are that bad, I usually cut them out and put new metal in.

I have no idea why this post is so wide, in that you have to scroll back and forth sideways to read it. Sorry.

Hope this helps a little, and might clear up some confusion and doubt regarding the shrinking disc.
 
You won't go wrong spending 115 bucks on that. The video shows in pretty good detail how to obtain a bondo free finish. Depending on how fussy you are, you can actually get a bondo free finish, but most of us are happy with just a hair of bondo, or shall we say, some spray on bondo. It really is not that hard to do, but you will need some patience.
You need to make sure when you mount the shrinking disc on the grinder that the flange nut is thin enough to not protrude past the surface of the shrinking disc. That is necessary so you can float the whole disc across the panel if need be. If the nut is too thick, like most of them that come as standard equipment, it will stick past the surface of the disc.
I use a nut from a Milwaukee grinder, that is easily obtainable at most jobbers. The Milwaukee nut is less than an 1/8 of an inch thick on the flange.
Good luck. I'm sure you won't be disappointed if you take the time to learn how to do it.
 
In addition to what John has already covered, if you are planishing an area that (as John called it) looks like the surface of the moon,
you might want to try using a slapper, as they have more surface area than the head of a hammer, and many well placed lighter
blows will get you better results than fewer hard hits. The whole Idea is to try and return the area to it's original shape with as
little stretching as possible.....

And in addition to the shrinking disc, if you have a stud gun, you can buy a shrinking tip for it, and it is capable of shrinking a
much smaller area than using the torch.

You can easily make slappers out of leaf springs, flatbar, etc, or you can buy them from a number of vendors.
I have some leafs out beside the garage, but have yet to drag them in and make any. Thus far, I have just used what the guy
on the Tool Truck calls a Light Dinging Spoon.

KMS has this one, which is almost identical to the one I bought off a Tool Truck back in the early eighties:)
You could start with one of these, then if you find you feel the need for one heavier or lighter, just make it from a leaf spring
or flatbar of the desired width/thickness......

https://www.kmstools.com/martin-dinging-spoon-6930

MAR-1036_MED.jpg



and here is the shrinking tip for Uni Spotter (aka: Stud Gun)
https://www.bestbuyautoequipment.com/h-s-autoshot-1007-stud-welder-shrink-tip-p/uni-1007-02.htm

HS-1007.jpg
 
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Finally another update just took it out for a rip.Did front fenders and 1 running board shield over the winter and cheated and got 1 shield and the running boards from Howell's Sheet Metal.Got all the lights and dash gauges working.It needs some suspension and steering tuning but ran down the road a 7/10.Here are a few pictures.
 

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Looking very good. Like the finished colour on firewall and grille shell
 
Looks good nicely done...I bought a shrinking disc because I hear and see other peeps using them and they say they work..and I wanted to try one... Well not so much for me...maybe I was doing it wrong or don’t have the patience..couldn’t get the metal to move the way I wanted..ended up with a bigger bump instead of taking it away...ended up frisbeeing it into the back field...see it every so often when I’m out there...just saying...
 
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