I have used something that was called a knife edge straightedge exactly as you described.
I think what I purchased was something else. It was dangerously sharp, it has 4ea holes for flat head bolts. Approximately 2.5*16*0.5". Also it was not particularly flat, off by about 0.01" if I remember correctly.
I have not tried to figure what kind of steel it is but may find a use for it some day.
I think what I purchased was something else. It was dangerously sharp, it has 4ea holes for flat head bolts. Approximately 2.5*16*0.5". Also it was not particularly flat, off by about 0.01" if I remember correctly.
I have not tried to figure what kind of steel it is but may find a use for it some day.