Grind Direction

[Jan]

Mr. Mark, you are not missing anything. In my understanding the oval grindstone is today a curiosity. 

It is not so easy to imagine how it works, and so I have prepared a model. I have assumed that the oval is an ellipse with axes ratio 4:5. The blade is guided by a jig which fixes the blade protrusion from a pivot.

When the vertex of the oval stone meets the edge than it grinds the desired bevel angle.

   

When the stone rotates towards the co-vertex, than the contact point with the blade moves away from the edge.

When the co-vertex of the oval stone meets the blade than we have reached the most distant spot of the blade.

   

Jan

[Rupert Lucius]

Jan -

Thank you for the model.

Thank you Thomas for sharing the art with the Exchange - got me to thinking!

Thank you Mark.

Rupert

[Mark Reich]

Mr. Thomas, I thank you again for joining us, and writing your exceedingly interesting, in depth posts. You are a treasure to the Forum!

Mr. Jan, I am truly in awe of your ability to immediately design and construct working models of abstract conception. Having the knife fixed in position was exactly what I was missing. I assumed the goal was indeed a convex edge, but without mechanical fixation, I couldn't see how any sort of precision was possible.

Thank you Mr. Thomas and Mr. Jan! This was truly a wonderfully unique and interesting lesson, which I will undoubtedly retain and be able to apply to other cammed apparatus and operations.

Wonderful, Gentlemen!

[Edgepal]

This is a nice picture, I have tryed to find it dor a while...

Thomas