Derek Cohen (in Perth, Australia)
Hi David

It is relevant to understand the context of my concern with a slight convex on the radius wheel. I wrote this up on my website in CBN article. In my case it comes down to the 180 grit wheel being used with the Tormek blade holder (the BGM -100). This runs past the wheel on rails, and needs the face to be aligned.

"The problem is that the Tormek has a friable wheel and, using the BGM-100 set up, the wheel can be trued to it. However the CBN wheels are not friable. Therefore there can be no adjustment. If the wheels are not square, then you are in trouble! On the other hand, if you are not using the BGM -100, then you have wider options".

My 80 grit wheel has a simple rest where blades are ground freehand. Nevertheless, a slight convex here means that only the centre of the face cannot be used by moving the blade across the wheel since there is a dip at that point.

Regards from Perth

Derek