Shrinking disc

W

wrndln

Well-known member
Has anyone on this board had much luck with using a sheetmetal shrinking disc? I bought one a couple of years ago and have used it some, but it doesn't seem to do much shrinking. I bought one after seeing the video on the internet about how it really can shrink a dented piece of sheetmetal quite a bit. It seems like it does a little shrinking but not all that much. In theory it sounds good where you only heat the high spots to shrink them down. I have a rear panel and the back front seat tub panel on my phaeton that have a lot of unevenness. Maybe a shrinking disc is not supposed to be used to even out panels like I was hoping. I have used a hammer and dolly to get the larger dents removed. I run the disc over the about a 4" to 5" diameter area of the panel for 20 to 30 seconds and then quench the area with water with a little dish soap in the water. Is this the correct way? Maybe there is a trick to it I don't know.
Thanks in advance for any help.
 
I have seen that vid of the egg shape metal he bashes in and shrinks discs out.

As with all those type of demos, they are done in a perfect easy world.

Unless you wanted to straighten a headlight shell, I doubt they would be much good for anything else.

Most car shapes are convex, and dings go in, the shrink disc is for heating high spots sticking out.

There may be places where they may work, someone may chime in that they worked on their stretch.
 
I imagine it works better on the beer cans they build these days, but Model A sheet metal is a whole other animal. You'd have to heat it with a torch and quench it.
 
It is a great tool that can do wonders, but you have to understand how metal moves to make the most of it.

You need a high speed sander. You need to quickly generate heat on just the high spots. A slow speed sander buffer will only heat up the whole section. The cheapy sanders will do the job for a little while before burning out.

You need to understand how the metal reacts to bumping and heat. I learned this by reading an older (1970 or so) autobody text book and buying some expensive videos. Now you can rent the videos for $10 at smartflix.com

Once you work the metal close to level then you go in and work it with the shrinking disk. You will need to keep bumping up the low spots and keep and eye your overall shape.

Once big mistake when working with heat and metal is knowing that the WHOLE panel must be allowed to come to the same temperature to check the shape of the panel. If one area is slightly warmer then the panel shape will be distorted. I do not like to quench the metal with water. Rather, I let the metal cool some by air and then use some water to help equalize the temp of the metal for checking. I walk away from the job once in a while so I can come back to fresh view of the metal.

Follow the link to my metal working hints.

Link to my metalworking hints
 
I have used the shrinking disc quite a bit but am no expert. Number one the part has to be bare metal with no paint on it. You also need a high speed grinder. If you get steam after you use it it is working. You migh have to use it 10 or 15 times in one area. You should tap up the low areas in between using the disc.
 
Hi Guys... for the 2 cents worth - this was invented about 30+ years ago by Scott Knight, and he sold the rights (his style) to Ken Sacumoto (sorry?) and Ken has been doing the videos and selling these for years. I attended 2 complete seminars here in Chicago that were put on by Scott & Fran Roxis at Frans shop - after 8 hours of watching this man do his magic I was a believer. I use these for stainless trim, grill shells, headlights, brass radiator tank tops for Tri 5s that people want to poilsh out for show cars. On a fender or door - a low crown deck lid or roof section, you can't beat it (no pun intended). Like any tool, it takes time to learn and there is a great benefit to using one of these; all the above comments will relate to the weight of the grinder, the RPMs it will produce, and what amp rating it will have in order to be pushed into a panel or fender with a great deal of force and not burn up or blow your circut breaker. The videos on Ebay and on U-tube will give you a lot of information, and the smooth sided discs that are sold on Ebay really do work well and are actually much safer to operate. Just keep one thing in perspective - you can do this 50 times, and probably not loose 1/1000th off the surface... how many times can you go over your hammer work with a 36 grit grinder before you make the panel thinner and it begins to have a personality of its own? Really, it works - but then so does a skate board, but I can't operate one, and I am too damn old to try and learn how without seriously hurting something I still might need.
 
steve hackel said:
Hi Guys... for the 2 cents worth - this was invented about 30+ years ago by Scott Knight, and he sold the rights (his style) to Ken Sacumoto (sorry?) and Ken has been doing the videos and selling these for years. I attended 2 complete seminars here in Chicago that were put on by Scott & Fran Roxis at Frans shop - after 8 hours of watching this man do his magic I was a believer. I use these for stainless trim, grill shells, headlights, brass radiator tank tops for Tri 5s that people want to poilsh out for show cars. On a fender or door - a low crown deck lid or roof section, you can't beat it (no pun intended). Like any tool, it takes time to learn and there is a great benefit to using one of these; all the above comments will relate to the weight of the grinder, the RPMs it will produce, and what amp rating it will have in order to be pushed into a panel or fender with a great deal of force and not burn up or blow your circut breaker. The videos on Ebay and on U-tube will give you a lot of information, and the smooth sided discs that are sold on Ebay really do work well and are actually much safer to operate. Just keep one thing in perspective - you can do this 50 times, and probably not loose 1/1000th off the surface... how many times can you go over your hammer work with a 36 grit grinder before you make the panel thinner and it begins to have a personality of its own? Really, it works - but then so does a skate board, but I can't operate one, and I am too damn old to try and learn how without seriously hurting something I still might need.
Click to expand...

Wow that is an analogy I gotta use sometime!!:D At the shop we use the one manufactured by Wray Schelin and we go through about two of them a year simply because we use them enough that we wear them out.



Rusty, I have it on my list to call you but we are closed this week and I am doing stuff with the family so I will fit you in somewhere. In the interim, let me start with the basics again...

In metalshaping, there are three basic things you can do to sheetmetal, stretch, shrink, & bend. While to many untrained eyes, people might think Model A's have flat panels but in reality, there many crowns (slight curves) in all of the panels. These crowns are actually slight stretches in the metal so using a shrinking disc in inappropriate areas can actually do more damage than good. I wish I or someone who has experience in this area could actually look at the panel and "read" where the problem areas are. It may be that it really needs to be wheeled or planished first to raise the crown of the panel.

The second item that one needs to remember is that the shrinking disc is not a cure all or a tool that eliminates a basic hammer & dolly. When we held the Fordbarn Workshops, we found that many people had incorrect perceptions on how to properly use a dolly --and that it was to raise a dent.

Finally, there is no need for soap in the water. A bar of soap applied to the stainless disc will deter galling from forming on the disc. The metal only needs to be heated just enough to create steam when water is applied. Applying heat that causes the metal to turn red, --or blue is only hardening the metal and defeating the purpose. Using a spray bottle (i.e.: Windex, 409, etc.) with water only that can be spritzed onto the heated area works the best for me. Using air blown across the surface also works but we use water because we are on the clock and experience helps guide us on how far to go.

Maybe we all need to have another workshop to refresh ourselves on how to do some of this. ;) Until then maybe we (me) can do a small tutorial to post, --or maybe you could get one of the videos out there that cover the basic concept.

.
 
I used the shrinking disk with good results. I also use a spray bottle and you what to see steam when you spray it and I also use compressed air. I use a little dish soap in the spray bottle but the bar of soap applied to the disk sounds like a good idea also.
 
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