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Old 05-30-2019, 06:56 PM
rkolenda rkolenda is offline
MetalShaper of the Month Nov. 2009
 
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Location: Rockford,Michigan
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Default shrinking with wood disc

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.IMG_1396.jpg. 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.
IMG_1375.jpg 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.

IMG_1377.jpgSwitch 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.

IMG_1378.jpgNow switch to the 1-1/4 forstner bit and drill the pocket to a depth of 7/16 inch.

IMG_1380.jpg Measuring pocket depth

IMG_1382.jpgNow switch to the 5/8ths bit and bore the spindle hole thru

IMG_1393.jpg. My DeWalt grinder uses an adapter with a small shoulder that we will need to allow for.Your grinder may be the same.

IMG_1389.jpgThis is the shoulder I was referring to.

IMG_1386.jpgLeave the 5/8ths bit to line up the center bore after flipping the disc then clamp it down

IMG_1387.jpgSwitch to the 7/8ths bit and counterbore the backside of the disc just enough to allow your adapter to fit flush.
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Old 05-30-2019, 07:09 PM
rkolenda rkolenda is offline
MetalShaper of the Month Nov. 2009
 
Join Date: May 2009
Location: Rockford,Michigan
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Default part 2

IMG_1388.jpgAdapter now fits flush

IMG_1342.jpgI 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.

IMG_1346.jpgNow I have 2

IMG_1391.jpgMounted to the grinder it is not quite ready yet

IMG_1398.jpg I first like to break it in by maying a few passes on a piece of clean steel plate to start the bevel

IMG_1399.jpg A side view of the bevel.
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Old 05-30-2019, 07:37 PM
rkolenda rkolenda is offline
MetalShaper of the Month Nov. 2009
 
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Default A demo

IMG_1400.jpg A piece of scrap .063 thick 3003 aluminum pulled from the bin.

IMG_1403.jpg A straight edge shows the crown

IMG_1401.jpg Here is a before photo of the surface

IMG_1404.jpgI 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.

IMG_1406.jpgI 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.


IMG_1409.jpgSince 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 .

IMG_1411.jpgHere is the same surface after the shrinking disc.No damage after shrinking all the crown out.
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Old 05-30-2019, 08:02 PM
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Kerry Pinkerton Kerry Pinkerton is offline
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EXCEPTIONALLY good tip Robert. I'll be making one for sure!
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Old 05-30-2019, 08:30 PM
cliffrod cliffrod is offline
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Default

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?
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Old 05-30-2019, 09:17 PM
BTromblay BTromblay is offline
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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
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Old 05-30-2019, 09:47 PM
rkolenda rkolenda is offline
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"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.
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Last edited by rkolenda; 05-30-2019 at 09:51 PM.
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Old 05-31-2019, 12:24 AM
Jaroslav Jaroslav is offline
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Robert. Good idea, I'll must remember. But I'll use a lathe.
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Old 05-31-2019, 05:27 AM
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Gojeep Gojeep is offline
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Thanks for showing this.
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Old 05-31-2019, 06:05 AM
RockHillWill RockHillWill is offline
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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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