Grading the grader

[jsbowman]

My Stone Grader has become concave in the middle.  Not from the long edge to the long edge, from the short edge to the short edge.  In other words, if I put it to the wheel It will make the wheel have a hump in the middle.  This plays havoc with plane blades and leaves them concave in the middle if I'm not careful.  I understand that it should have the wheel shape running long ways.  And I have that, it's also got a depression running the other ways.  Can I rub it on concrete or a sanding belt to bring the ends down, or is it just trash?
Thanks in advance
Josh

[Jeff Farris]

The grindstone will cut it in only a few uses, so I wouldn't worry about flattening it.  Shorten your side to side stroke when you use it.  I don't move more then about an eighth of an inch side to side when grading to fine. If you don't "scrub" side to side, you'll notice less crowning and your grader will soon have a straight line across.

Also, regarding cutting a concavity in your plane irons, Make sure you take the left edge of the iron all the way to the right edge of the grindstone and the right edge of the iron all the way to the left edge of the grindstone.  If you use a short stroke where the edges leave the grindstone, but the middle of the blade never does, it doesn't matter how flat your grindstone is, you'll cut a concavity in your iron. Use all the grindstone on all the blade.

[jsbowman]

thanks for the reply.  my grader was so severe, I decided it was trash, so I took it outside and rubbed the heck out of it on a flat piece of rough concrete.  After about 5 to 10 minutes of very hard rubbing, the grader is again flat and it did not reduce the thickness much.  Good words on the method to use it.  Now I have a fresh start and can do it right.
Thanks again
Josh