I too use a hole drilled in a wooden block at a 2 inch depth to make
sure that the end of the bowl gouge is extended to the same length
each time.

But also, on my Wolverine setup, I have a small hose clamp on the
slide that holds the cradle used for my Ellsworth jig. It is
tightened to the exact spot for grinding my bowl gouge. Most of the
other tools that I grind on that side of the grinder need more length
so I can pull the slide out to grind those tools. When I am done I
can push the slide back to the exact spot for grinding my bowl gouge
and it will stop where the hose clamp is attached.

Hope that makes sense. Its actually easier the use than it is to
explain in words.

Ted