VALVE GRIND TIP
If you use a Sioux valve grinder or any valve grinder that centers on the chamfer of the end of the stem of the valve, it is very important that the chamfer is concentric with the valve. When I use the V-block attachment, I use a piece of wood with a notch cut in it to hold the valve in the V-block. This works much better than trying to hold it down with your thumb. I have found the stem chamfer on some new valves are not concentric as I always reface new valves just to make sure they are true. I find about one or two out of a hundred to be out of shape.

Wes Schell
Schell Machine
Gregory, SD
July, 2018