Thanks for the extra details of this one Bill.
I made mine with a threaded insert screwed into the body. I couldn't 
find any thumbscrews anywhere so went with a plain bolt which is not 
satisfactory. Also mine is more prone to chatter than my regular scratch 
stock because of the longer unsupported blade area so I think these need 
a thicker blade than the usual ones.
regards, Peter

Bill Taggart wrote:

> small block of rosewood with a saw kerf in it, to hold the small scrap of
> saw blade (which is what he uses - old trashed hand saws), with a hole
> drilled and tapped to take the brass thumbscrew you see.

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