Urethane Tires and Sanding Discs

[SteveMaryland]

I don't even own the Shopsmith 555435 conical sanding disc, but anyway I did a "flat pattern" layout for a 12 inch OD, 4-degree conical sanding disc just to see how or if a standard flat abrasive pad could be cut to fit (to avoid buying the Shopsmith pads). On the website, Shopsmith does not say what the OD of the conical disc is.

Geometrically, not much difference between flat and 4 degrees. Doesn't look like it would be difficult to just use a flat piece of paper and cutout a 1.0 degree wedge to make it fit the 4 degree cone.

I see that the Shopsmith conical paper pads have a tangential rather than a radial cut (as shown below). That might be important to keep the seam from catching the workpiece but I don't know. Eventually I will get the disc, but I hate having to buy special ($) paper for it.

CONICAL SAND DISC DEVELOPMENT.JPG (52.6 KiB) Viewed 492 times

[jsburger]

I under stand not wanting to spend more money than you have to. But, the SS conical sanding disk is a special disk. Nobody but SS makes it (I think) so nobody but SS sells the sand paper. If you look at the SS catalog the conical sanding disk paper is slightly cheaper than the flat disk paper Of course you can get 12" flat disk paper cheaper elsewhere.

[DLB]

Scott Markwood did a video on cutting your own conical disc abrasive because he was advocating a finer grit than SS sells. IIRC the product he was primarily demonstrating was the SS sharpening jig for Jointer and Planer knives. I don't recall if he did it this way, but one can simply use an SS abrasive, or even a backing, for a pattern. The tangential cut makes sense to me, for the reason Steve gave. The SS discs are 11-1/2" OD, flat pattern, and the tangential cut is ~1/8" wide. The SS cut is straight, not a wedge, when the material is flat. It gap does take on a wedge shape when mounted.

Caution about using science, the discs are not particularly close to 4 degrees. It's been a while since I measured, but IIRC it was closer to 3 degrees than 4.

I haven't tried it, but a coarser than offered grit may also make sense for some users, as it may allow more material removal per pass when sanding to thickness or width.

- David

[chapmanruss]

I have to wonder if it is a good idea to spray new adhesive over old adhesive that no longer sticks. It may make an old PSA Sandpaper Disk stick to the metal Sanding Disk but will the old adhesive release from the paper backing and still come off the metal Sanding Disk leaving a bigger mess of adhesive.

As David mentioned I too remember the video Scott did on making your own Conical Sandpaper Disks for additional grits. Something I have considered doing the next time I need to sharpen Jointer or Planer Knives.

Below I have added a picture of a Conical Sandpaper Disk for reference. The center cutout is 2-3/4" in diameter.

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Conical Sandpaper Disk.jpg (322.8 KiB) Viewed 451 times