Ruler measured in 12ths of an inch, I saw a post about this in the metric vs imperial

[Roger Nair]

The twelth scales on the back side of the framing square enabled carpenters to cut rafters reliably using field measurements of overall rise and run. Lets say the run is 13'5" and rise is 8'7", without calculation or knowledge of rafter length, the carpenter could set gauges on the square to 13 5/12" and 8 7/12" and step off the rafter in twelve steps. Bingo, done!! All kinds of scaling problems of a foot to inch are handled by inch to twelth.

[lowell holmes]

Sometimes a carpenter's square is out of square a bit. You can open a square a bit by putting a center punch at the haunch inside, and vice versa by placing the pinch near the outside corner.
They really are neat tools. Of course, you strike the center punch with a hammer.

Another neat use is in locating a pipe's center line, put the crotch of the square on the o.d. of the pipe and the center of the pipe will be where the blade touches the pipe.

[steven c newman]

The ruler I picked up awhile back, a Starrett No.0601

Of the four scales on the 12" long, tempered steel ruler:
One is in 12, with a section in 24, and the final section in 48
One is in(on the same side)10, then a short section of 20, then 50, then 100
Flip the ruler over
One is in 14, then goes to 28 for the last "inch"
Finally, there is a scale in16ths, then a section in 32nds, then the final section in 64ths.

makes one pay attention to what scale they were using.
Might have been to make scale drawing??

As for a "book", somewhere in the house is a blue book by Swanson.....used it quite a bit when I was doing stick framing...

[John Gornall]

I had an old rule graduated 12 lines per inch and found out it was a printers rule for laying out text at 12 letters per inch.

[James Pallas]

I try to look at any graduated measuring device as a means of portability. If you use a ruler or tape or such it is a help to move a measurement from one place to another. If are are marking the length of table legs for instance, mark one leg with a tape then mark the rest fro the first. If you use a tape for all four you have three chances to make an error. No matter what you use to measure inches centimeters a stick it is just portability. The first chance you get to introduce a fixture of some source use it. Marking gauge, combo square, set up block, chisel width or such. Just my opinion of course. I think you will find lots of patterns hanging on the walls of old shops, less chance of errors.
jim

[Jim Koepke]

For some reason this morning the normal reply window isn't working. So instead of copy and quoting my reply is with quote and cut up.

If you use a ruler or tape or such it is a help to move a measurement from one place to another.

About 40 years ago I worked in a silkscreen printing shop. I noticed one of the shop made rulers didn't fully agree with another ruler. They laughed and told me about a slight problem they had many years earlier. Something didn't measure exactly to a customers specification. It really wasn't critical the person was just being difficult.

The owner and the manager took out their tape measures and put them against the standard rule I was using. At certain points they didn't agree. I think the technology of making tape measures and rulers has improved, but most of the time, being a 32nd of an inch off over 10 feet isn't going to be a deal killer.

I think you will find lots of patterns hanging on the walls of old shops, less chance of errors.
jim

Besides, why redraw something every time you want to make another?

I even make patterns for circles so I don't have to break out a compass every time. Besides, having a pattern makes it faster to put a radius on a corner than using a compass.

jtk