Christopher Tidy writes:

I can't quite get my head around what you're doing here. How can you
have the screwdriver tip tangential to the grinding wheel, and the
shank resting on the toolrest? Surely the two positions are 90 degrees
apart?

The toolrests on my grinder are adjustable. I'm not sure I've ever
seen one that wasn't. Even if yours isn't, for an application like
this you could be resting it on the far edge of the rest.