Shape of stone for sharpening blades.

[Mark Webb]

I have been using the 3/8 ruby stone from Suffolk. What I would like some help on is how to shape it to do the best job.

[Kansas]

Is it a sharpener from Cooks? That I have some experience with. Put the stone on, take a diamond dresser, and start dressing the incoming side. You might dress the very corner of the outgoing side, but lightly. That always gets wore down first, and requires reshaping the whole stone. After you get the stone dressed somewhat, put it on a blade, and lightly kiss the blade with the stone. Grind and correct the needed areas as needed. If you need a diamond dresser, Suffolk sells them pretty cheap. As the blade goes around, you can correct the stone. I start with getting the down side against the face of the tooth first. Adjust that so it lightly grinds that. Then the upside of the gullet is a lot easier to  do.

If its not a Cooks, I don't know. Make sure you have the correct cam on.  (Don't ask me how I know.)

[Tom]

Shaping a stone for a cam grinder isn't too difficult when you realize what the cam is doing.

The trailing edge of the stone, the one that grinds the face of the tooth, is not affected by the cam, other than having the depth controlled. 

The sharpener needs to be set such that the rake (hook) of the tooth is proper, as the cam drops it into the transition area.  The shape on that side of the stone has to match the transition area at the base of the face of the tooth.  The reason is that the stone doesn't travel forward until the transition area is cut.  Once the transition area is cut, the cam takes the stone for its ride into the gullet where the flat base of the stone does its job. Then the cam begins to lift the stone on the back of the tooth and, the better that the angle of the stone matches the slope of the back of the tooth, the more stone contacts the metal, and the more efficient the grind.   

You can make some adjustments to get a taller tooth by manipulating the angle of the back of the tooth, but not much.  Lowering the slope of the stone contacts the back of the tooth earlier and ends up shortening the tooth.  Making the slope steeper will make the tooth taller. (I think I have that right)

This is fine for finessing a tooth, but isn't a replacement for a proper cam.

The things that are important about shape is that the transition area is rounded and smooth so that the sawdust flows into the gullet and doesn't jam at the base of the face; the gullet is deep enough to carry the sawdust and the tooth is at least 3/8 inches tall. (measured from the base of the face)  correct that to 3/16.

Neither the color of the stone, the grit of the stone, the composition of the stone, nor the speed of the stone has anything to do with the shape.

[LeeB]

3/8 seems a little tall to me, unless you are talking from the bottom of the gullet. About 3/16 - 1/4" sounds more reasonable to me.

[Tom]

You're right LeeB. That's the second time I made that mistake in just a few weeks. I'm becoming addle brained.   If I keep this up, I'll have to leave this stuff with you fellows. 

[LeeB]

That's ok Tom. I learned the hight from you any way so all is good.

[bandmiller2]

As you use the wheel keep dressing it back, keeping its form, outherwise you will keep getting less and less hook as the wheel face that contacts the front of the tooth wears.I have had the best luck with the blue ceramic wheels from Cooks.Frank C.

[Mark Webb]

Thank you all for the advice