Okay, don’t laugh at me guys okay? But I have an HO ruler like I’m sure most of you do and I think it’s pretty darned nifty. However, since there are no instructions with this General brand ruler I have a question about it.
On the left end, in HO scale, it doesn’t start with 0, it starts with a 9 and a 3. Can anyone please tell me what the 9 & the 3 mean?
Thanks for answering something which will probably seem obvious after it is explained to me.
Paul the newbie (hey, ya gotta start somewhere right?)
Those small tick marks to the left of the zero are one foot of HO scale inches.The 3 and the 9 are labeled. The “6” in between them is not.
In measuring something, you line up the nearest foot mark on the right and then read the remaining inches on the left. Similar to an Architect’s scale rule.
The increments to the left of the 0 with 9 3 are measurements in inches(1 foot) - count them---- if there was room it would read 12 9 6 3 0 . - - - see the scale below S gauge and it’s the same only the 12 is missing. You are not the first person on earth to query those numbers.
The design if the scale is based on an engineer’s drafting scale from back in the days when engineering drawings were done on paper and digital did not exist.
Refering to the picture above, the divisions on the right of the 0 are in feet and 1/4 feet (3 scale inches), the divisions to the left of 0 are scale inches. The idea is that, if you want very precise measurments to the inch, place the scale rule so one mark is on an even foot and other mark is somewhere in the inches section. This will give you a measurement to the nearest inch - like 34’-7". This applies to the other scales on the ruler as well.
In practical usage, the HO scale inches are so small, I just use the quarter foot marks, but some people doing very close work (rivet counters[swg]) would use scale inches.
