Hi Charles,
I think you just want to convert from real life to HO scale. Just use the calculator on your
computer if you don't have one. Here's an example:
Say the door you want to re-create in HO is 3'-0" x 6'-8".
The height is 80 inches, so enter 80 on your calculator.
Divide by 87.1 and you will get 0.91848............etc.
If you have a 6" decimal ruler then your door will be 0.92 inches tall,
or as close as you can measure it!
If you have a fractional ruler then multiply the 0.91848.......etc. on your
calculator by 32 and you will get 29.39.....etc.
Throw out the decimals and call your door 29/32" tall.
Now the width of the door is 36", so enter 36 on your calculator.
Divide by 87.1 and you will get 0.41331...........etc. Multiply
by 32 and you get 13.22...etc. Throw out the decimals and call
your door 13/32" wide. Or on your decimal ruler just measure close
as you can to 0.41".
So the basic steps are:
1. Figure or measure the real world lenghth in inches that you want to scale down.
2. On the calculator, divide that number by 87.1
3. You now have the decimal inches for your model. If you want it in 32nds,
just multiply by 32! Or if you want it in 16ths, just multiply by 16 instead.
The calculator does all the arithmetic for you, you can follow the same steps
for any "real life-to-HO" conversion.