conical disc sanding

[Nick]

"I'm still not totally sure what the conical sander will do that the flat sander won't, though. Can't I just angle my fence a little and do the same thing Nick was doing - taking off a precision amount from my workpiece, as the PTWFE suggests? How is the conical disk any better?"

Yes, you can use the flat disc to do the same thing as the conical sander -- for about 5 minutes. Maybe 10 or 15, if you're sanding softwood. After that, the grit at the edge of the flat disc is gone.

Because the conical sander is, first and foremost, a cone the wood will make contact all along a line from the center of the disc to the edge. If you wear out the grit in one spot, just raise or lower the table so the wood meets a new spot on the disc. This is impossible to do on a flat disc. Once the grit is gone from the edge, you're screwed.

Originally, the conical sander was conceived as a way for folks to sharpen jointer and planer knives on the Shopsmith. You cannot accurately sharpen these cutting edges on a flat sander. And in a lttle less than two weeks, I'm going to show you something else you can do with the conical sander that is impossible with a flat disc -- precision thickness sanding. Be sure to watch that segment on Sawdust Session #14.

With all good wishes,

[a1gutterman]

Looking forward to it Nick: I am all signed up. Did the monitoring of Session 13 help? Are we going to see improvement?

[rdewinter]

[quote="charlese"]... I mounted some 12" flat disc sand paper and installed the disc and tilted my table until I was square.

How did you use flat sand paper? Did you cut out a pie slice?
The only sandpaper I had was 12" flat for the flat disk. I admit it didn't seem to fit correctly, there was a bubble in it and it didn't lay flat and no hole in the center. It seemed to flap when turning. I knew it wasn't right. Need to order the right paper.

I used an engineers square to check square but my gauge only read 3+ degrees. Since I was square I didn't bother refining my table top. I set the table about 1/16" from the disc. Used a scrap 3" test piece and set my fence at 2 7/8".

I'd check your trunnion indicator plate.

Yes it may need a fine adjustment

It seemed like the leading edge of the disc is like the leading edge of a saw blade. Won't that produce excessive wear on the paper? How do you measure from the disc to set the fence as the disc has a 4 degree tilt? When I set the fence with a blade I measure from a static point, ie saw tooth tilting toward the fence. I produced a really square edge and face with my test piece but how do you achieve accuracy (for example, I want square stock at 2 1/2")?

I don't set my fence the way you did. I set it at the same thickness as the board before sanding, then use the spindle to make adjustments.

I didn't think you were suppose to use the spindle.

[jimthej]

Since we are talking about the conical sander, can I ask a question?
I did a little canvas stretcher frame the other day and got the stock 3 square using the jointer on 2 sides and ripping the 3rd to width. That was fine. Since I don't have a planer I did not try to square the 4th side. Would it have been possible to square the 4th side using the conical sander?
Not having that 4th side square caused some joint problems.

[charlese]

Jim - Sure you can! When building some cabinet doors, a while back, I used the conical disk sander in a similar way. Wanted to sand down the bottom of the stiles, which stood a little proud of the rail. Set up the conical disk and used my miter gauge with extension to push the door across the table. I went with light sanding removals and it worked perfectly! Results; a nice square, flat door bottom.

rdewinter - Incidently, used the Mark V quill extension to control the amount that was sanded off for each pass.