removing the disc from a 20" disc sander

[dustin wassner]

Brand name is Wilton, but it looks to be the same design as all the others: 3 bolts that thread into the back of the disc and hold it to a hub that attaches to the motor shaft. The center of the disc has a hole that looks to have a precision fit around a ~1" disc, I assume to attain perfect concentricity.

I took off the 3 bolts from the back of the disc, but the disc did not freely come off. Is there something press-fitted on? I only ask because I would rather avoid the attempt with a deadblow if there is something pressed on. I did not attempt to remove the small center disc.

FWIW, I am looking to shim the disc away from the hub roughly .001 in one spot.

thanks,

DW

[Geoff Crimmins]

It's possible that the joint between the disk and the hub is tapered, and the three screws pull the taper together. The spindle adapter on my wood-lathe chuck works like that. On my chuck there are two additional threaded holes on the adapter which you thread the screws into to press the adapter off of the chuck. Is there anything like that on your disk sander?

--Geoff

[Bill Dufour]

I suppose there may be a circlip under that 1" cover. I would try to push the disk on to see if it moves that direction.
Bill

[Bill Orbine]

If you know the model number of your sander, you may be able to Google up parts and see the exploded view of your machine. From there you may be able to determine if there are any other fasteners, retaining rings, etc.... . Websites like ereplacement often show exploded views of the machine in question.

Keep in mind your machine might be similar to the Jet brand.

[Cory Newman]

Research before prying it off. I broke my powermatic not knowing it was keyed to get tighter the more you pried.

[Bill Adamsen]

Dustin: Like most, I disassembled my machine (Rankin/Apex 16") when I got it many years ago and reassembled truing it up with a dial indicator and shims at that time (a time-consuming process). It has needed zero adjustment since then, and time clouds the details of how the platen keys onto the hub. Not sure if Wilton used the same design. The hub has three bolts and if I remember correctly, minimal keying into the platen. Unbolted, the platen basically dropped off the hub. Getting the hub off the arbor is another story altogether. My suspicion is that this will not help you much.

[dustin wassner]

I was able to get it off by just removing the center locating disc. I went through the shimming process and was able to get the outer edge of the face of the 20" disc to .005" tir (measuring like the image in Bill's post). Has anyone had luck getting less than this? I messed with it for quite a while and found that this was the least I could attain.

[Bill Dufour]

I would think the disk may not be that flat. I suppose you could have it ground flat but it might move as the stress gets relieved.
Bill

[Ronald Blue]

When you rolled it was the runout progressive? As in was the "0" 180 degrees or very close to it from the .005? One thing to consider is you are a long ways from the center line to the outside edge so it's going to be very sensitive to shimming. You can get shim stock down to .001 but that might be to much still. I think it's going to require a lot of trial and error to shim it closer. You could possibly use a sanding block and true it in place but you run the risk of making it convex but that might not be an issue depending on your planned usage.

[Bill Dufour]

You could rig something up using the mitre slot and a sanding block to true the face so it is parallel to the slot. You say it is off by a small amount. Is it off the other direction, either in or out, tapering around to 180 degrees across the disk? If not then the disk is not flat.
I think at this point you need to determine if the disk is flat or not.
Bill

[Bill Adamsen]

I went through the shimming process and was able to get the outer edge of the face of the 20" disc to .005" tir. Has anyone had luck getting less than this?

Your post prompted me to check mine. I have paper on the front so I checked the back of the disc and measured .006". That seems to work fine for me. I've been using it like that for years. The disc is hard to shim because the shim goes in about 2" from the disc center and the edge is 8" from the center. In theory, the impact of the shim thickness is multiplied by 4. But it is such a lot of work to get the disc off and back on again that you are tempted to stop when it is "good enough." And I feel mine qualifies for the degree of precision I need. Looks like 4" more diameter you did good!