This question is NOT about the rafter table found on modern framing squares. I understand most of how that works, and the rows are generally labeled as well. Curious dopers who have no idea what I am on about can refer to this Wikipedia article which explains the rafter table on a modern framing square.
Instead, I’m holding a PEXTO B-14 framing square, inherited from my da. No date, or patent numbers, but it is made in USA, if that gives a clue. Like modern squares, this one has a table inscribed on the blade. The table is 7 rows deep, and columns align with the inch markings (2 -24) similar to modern practice. There is no text explaining the significance of the table. Googling, and searching the dope, yields only explanations of modern squares.
UNLIKE modern squares, this table does not seem, in general, to contain hypotenuse lengths for various rafter pitches and configurations. (straight, hip, valley, etc. Also, instead of the usual 4 or 5 rows, this table is 7 rows deep. A couple of the entries DO correlate with rafter lengths, the 7th entry in the 16 column is 20 for example, but these seem to be the exception.
Also, most of the values only include one “decimal” place, though a few contain two…most being X.10, and a few cases of X.11 I thus suspect that these are not decimal values, but rather feet and inch notations. Also, I have used decimal points here, but on the table, there is only a (obvious) space.
I’ll post the whole freaking table if no doper can help, just that it is 22 x 7 so 154 values, and some of them are difficult to make out.
As a start, I note that the “12” column is unique in only containing integer values, those being 8, 9, 10, 11, 13, 14 & 15.
Also, none of the columns below 10 contain any values greater than 12, so this can’t be any sort of normal rafter table.
