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Posted by: bbrock Jun 13 2017, 09:05 AM

I've seen shrinking discs mentioned or discussed on a few older threads but would like to see what people think today.

I have a small oil can spot (~ 3" wide) following a panel patch that needs to be shrunk, and I'm sure there will be more before this project is finished. I don't own an O-A torch but have MAPP and Propane. But the discs look like a much safer and less error-prone way to go. So what do you think of these things? Better than a torch for a nube? Are they all pretty much the same, or is there a particular one that stands out as better?

Probably going to mount it on my ancient, bomb-proof 4" Makita with a 5/8" arbor adapter. I have an old 7" Craftsman that I rarely use because it is unwieldy and impossible to get into many places.

Thanks! This community rocks!

Posted by: 914GT Jun 13 2017, 09:15 AM

I like to use a shrinking disk. It gives me better control and I can apply heat only to the high spots. A torch works but you have to be careful or you can make things worse. I used the disk quite a bit to straighten the sides of a 59 VW bus last year. It can get noisy when using it, so hopefully you don't have neighbors close by.

Posted by: 76-914 Jun 13 2017, 09:22 AM

Anyone have a video of one of these being used?

Posted by: bbrock Jun 13 2017, 09:36 AM

This makes it look easy.

https://www.youtube.com/watch?v=rt07pLebQwQ

Good to know about the noise, but I think I'm okay with the neighbors... Here's a pic of my house:

Posted by: maxwelj Jun 13 2017, 09:58 AM

One of our members has a how to thread.
http://www.914world.com/bbs2/index.php?showtopic=67022

Posted by: rick 918-S Jun 14 2017, 06:27 AM

Try one. They work Great with practice. they are on ebay all the time.

Posted by: LowBridge Jun 14 2017, 06:34 AM

they work fine for small adjustments when trying to reduce a high spot, but it works best if you use 2 people... 1 to heat and 1 to cool quickly with a cool wet rag, you will have more control using 2 people

Posted by: jpnovak Jun 14 2017, 06:53 AM

I have a 4.5 inch shrinking disk that works great. Its perfect for pulling dents.

If you have an "innie" dent you push it out to make an "outie" and then shrink it down.

I like the smaller one since I can operate the grinder with one hand and a wet rag in the other. You can see the high spots "blue" when heated and then shrink them down.

My method is to hammer and dolly to shape and then use the shrinking disc to effectively plannish the surface finish. They do not work great on inside concave curves. Just from the standpoint of access.

Posted by: Mark Henry Jun 14 2017, 07:02 AM

What ever happened to John Kelly and ghiaspecialties?
He seems to be MIA now.

His shrinking disc had issues with edge cracking and he recalled them.

I see most discs is just a stainless sheet pressed to shape, couldn't you make the same out of some SS 1/8" plate?

Posted by: 76-914 Jun 14 2017, 07:24 AM

Posted by: Spoke Jun 14 2017, 09:24 AM

I have a shrinking disk but not used it much. The directions said to spin it at 3500 RPM but my buffer only does 1800 RPM. What tool will spin it at 3500 RPM?

Posted by: rhodyguy Jun 14 2017, 11:54 AM

John and his wife bought and are running a bnb over on the wa coast in moclips.

Posted by: bbrock Jul 10 2017, 10:33 AM

Just wanted to give a "thank you" for all the feedback you gave on shrinking discs. I bought one and had the chance to use it over the weekend. Great tool!

Worked on repairing rust on the tail and rear trunk section. On the tail, I had to weld up a bunch of holes left by the spot weld cutter. That left the surface a bit lumpy. It took several passes with the shrinking disc and some hammer and dolly, but I got the lumps smoothed to within 1/32". I think I could get it perfect with more hours of work, but I'll take the 1/32" of filler in exchange for time to move to other challenges. On the trunk floor, I cut out the old chassis number stamp from the donor piece, welded in a blank, and stamped the correct number for my car. Felt like a car thief doing it, but it was fun. But ended up with about a 1/4" high bump at the edge to be butt welded due to stretched metal. Several passes with the disc and just a little hammer and dolly brought everything back to straight for a tight butt weld.

I'm sold! And very impressed with how easy and darn near foolproof it is.

Thanks again for steering me right.

Posted by: Mark Henry Jul 10 2017, 10:49 AM

Nice property...are you a dental floss tycoon?





https://www.youtube.com/watch?v=DmcYTShN4Fk

Posted by: bbrock Jul 10 2017, 02:30 PM

Thanks. I wish I owned more than 23 acres of that view, but we like it. I live down this road a piece:



Okay, maybe not.

That photo of my house is kind of a lie because the view blocks out the four houses of my neighbors. But I have to walk a bit to get to them. All in all, not a bad place to hang out.

Posted by: Dave_Darling Jul 10 2017, 03:29 PM

Hey, I already made that joke in his intro thread!!

--DD

Posted by: Mark Henry Jul 10 2017, 04:12 PM

Funny our place is also 23 acres, similar but our hills aren't that big.


Great minds...

Posted by: bbrock Jul 10 2017, 05:11 PM

Technically, we have 23 and 1/2 acres... but I don't like to brag

Posted by: larryM Jul 16 2017, 12:52 PM

check out this thread

https://www.jalopyjournal.com/forum/threads/sunchaser-shrinking-disc.711982/

i b'ot the sunchaser stuff many yrs ago when he was touring all the big regional car events with his demo

today we get 'em cheap fast-&-free and don't have to buy DVDs anymore - the usual competitive encroachments apparently put him out of biz, same as Kelly

also see this
https://www.google.com/search?num=40&newwindow=1&q=sunchaser+shrinking+disc&sa=X&ved=0ahUKEwih___jt47VAhUFw4MKHfwHDN0Q1QIIsgIoBg&biw=1326&bih=758&dpr=1.25

and
http://www.hotrodders.com/forum/tools-harbor-freight-168073.html

they work