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rkolenda 05-30-2019 06:56 PM

shrinking with wood disc
 
10 Attachment(s)
I started to use these wooden disc with my 4.5 inch grinder a couple of years ago on aluminum panels to shrink without damage.I was not happy with the galling left when using a stainless steel disc.It worked well and I am now using wood to shrink steel as it produces plenty of heat.The disc is made of hardwood.I use maple but other hardwoods should work.No softwoods. Due to the high rpm of these 4.5 inch grinders I won't go any larger than 4.5 inch disc diameter.The first discs where made on a lathe and took to long to make so I decided to try to make one as simply as possible using common tools that most of us have access to.Attachment 52994. The tools needed are a 4.5 inch hole saw and arbor. A 5/8ths ,7/8ths and 1-1/4 forstner bits.A 1/4 inch piece of drill rod.You will also need access to a drill press and a couple of clamps to keep things from moving out of alignment.
Attachment 52995 First pick out a piece of hardwood and inspect it to make sure that there are no splits or knots. Cut out the disc using the 4.5 hole saw afterwards the 1/4 inch pilot hole left from the arbor will be used to line up the disc for the next operation.

Attachment 52996Switch the hole saw for the 1/4 drill drill rod (a 1/4 inch drill bit would work also)to center and align the disc then clamp it to the drill press table.

Attachment 52997Now switch to the 1-1/4 forstner bit and drill the pocket to a depth of 7/16 inch.

Attachment 52998 Measuring pocket depth

Attachment 52999Now switch to the 5/8ths bit and bore the spindle hole thru

Attachment 53000. My DeWalt grinder uses an adapter with a small shoulder that we will need to allow for.Your grinder may be the same.

Attachment 53001This is the shoulder I was referring to.

Attachment 53002Leave the 5/8ths bit to line up the center bore after flipping the disc then clamp it down

Attachment 53003Switch to the 7/8ths bit and counterbore the backside of the disc just enough to allow your adapter to fit flush.

rkolenda 05-30-2019 07:09 PM

part 2
 
6 Attachment(s)
Attachment 53004Adapter now fits flush

Attachment 53005I cut a 5/8 x 11 nut in haft because the standard nut is too thick. Thinner nuts are available thru supplies like McMasterr Carr and others but I didn't think I needed a quantity of 25 at the time.

Attachment 53006Now I have 2

Attachment 53007Mounted to the grinder it is not quite ready yet

Attachment 53008 I first like to break it in by maying a few passes on a piece of clean steel plate to start the bevel

Attachment 53009 A side view of the bevel.

rkolenda 05-30-2019 07:37 PM

A demo
 
7 Attachment(s)
Attachment 53010 A piece of scrap .063 thick 3003 aluminum pulled from the bin.

Attachment 53011 A straight edge shows the crown

Attachment 53012 Here is a before photo of the surface

Attachment 53013I use a mixture of water with a bit of dawn disc soap to cool the panel after shrinking.It also cleans the residue left from the disc.

Attachment 53014I did not have someone to take a photo of me using the disc but it is used dry NO Lubrication . After using the shrinking disc .I cool the panel using a chip brush. The steam rising doesn't show in this photo.After checking progress on the panel I wipe it dry before the next round of shrinking.NO LUBE.


Attachment 53015Since this was just a scrap piece used for this demo I over shrunk it a bit .If it was an actual panel I would have been more careful .

Attachment 53016Here is the same surface after the shrinking disc.No damage after shrinking all the crown out.

Kerry Pinkerton 05-30-2019 08:02 PM

EXCEPTIONALLY good tip Robert. I'll be making one for sure!

cliffrod 05-30-2019 08:30 PM

Very cool, Rob. Thanks for sharing. I just got a hole saw about that big. Looks like I'll be putting it to use for some new tooling asap...

Is your grinder variable or single speed?

BTromblay 05-30-2019 09:17 PM

Hi,

Bob had shown me the wood shrink disk a while back for aluminum and I haven't used my stainless disk since. Works very well in a 4 inch grinder. The left over black char on the surface comes off easy with water and a scotch bite pad, will try the dish soap trick.

Thanks for sharing,

Bill

rkolenda 05-30-2019 09:47 PM

"Is your grinder variable or single speed?"Hey Clint ,I use a single speed grinder.The 5/8 x 11 spindle size seems to be quite a common size but it should be easy enough for the guys worldwide to change up for their needs.

Jaroslav 05-31-2019 12:24 AM

Robert. Good idea, I'll must remember. But I'll use a lathe.:)

Gojeep 05-31-2019 05:27 AM

Thanks for showing this. :)

RockHillWill 05-31-2019 06:05 AM

Bob was kind enough to make one of these for me a while back. It works extremely well. So well, that I loaned it to some one who must love it! Thanks for posting all the pictures.


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