I'm thankful I did not start with the 12 ruler. Both are Starrett, the 12 inch is off on every scale. It's a progressive error, it gains .0208 every inch. Off an 1/8 every 6 inches. Had this for years, Never caught the error until today. Starrett says there warrantee is one year.
Look very closely at the markings on the scale. It may be a shrinkage scale, used in the castings industry to measure patterns. It compensates for shrinkage in different cast materials after they cool.
Could it be a Pattern makers rule?
They are out to allow for shrinkage when casting, hence patterns are made larger.
I learned something today! I didn't know that such a thing as a pattern maker's rule existed.
Thanks Guys, that is what it is. It is marked - shrink 3-16 to the foot. If anyone needs it I'd love for it to go to a good home to be used. Thanks again, Bob @ 903 824 1949.
Bob I sent you a PM.
It has been years since I heard of one of those! Interesting thread.
Wow! The things you learn on this forum! I have never heard of those either. Dave
Yeah, handy rule to have.
I constructed my first pattern using a standard rule and a calculator working out every dimension.
What a job, but worth the result.
Pic attached, hot rodded timing cover for a flat head Cadillac V8 1937 thru to 1948 I believe.
Had a surveyors tape measure once, didn't have inches on it, it was divided into 10ths of a foot.
That's referred to as an "Engineers" rule - we use them in road building.