Scribing For Equality

My idea is for laying out three, equally spaced locations on a turned diameter. Establishing such locations is often a requirement for installing setscrews or bolts to secure a mating piece. Rather than set up an indexing device when this type of job isn't too critical, I chuck up the intended part in any three-jaw lathe chuck and scribe lines on the part using the chuck jaws as guides. Then, it's just a matter of eyeballing the scribed lines in a knee mill and drilling the holes.Mike Giaraffa, Maryland heights, Md.