To get the appropriate scale that I want I measure the 1:1 unit and then divide that number by 12 getting the measurement in inches. I then divide this measurement by 14. I then match my answer against the following chart, keeping the whole number and adding the following as appropriate, by rounding to the nearest number:
Inch: Fraction, Decimal Equivalent Chart
1/32 0.03125 2/32 : 1/16 0.0625
3/32 0.09375 4/32 : 1/8 0.125
5/32 0.15625 6/32 : 3/16 0.1875
7/32 0.21875 8/32 : ¼ 0.25
9/32 0.28125 10/32 : 5/16 0.3125
11/32 0.34375 12/32 : 3/8 0.375
13/32 0.40625 14/32 : 7/16 0.4375
15/32 0.46875 16/32 : ½ 0.5
17/32 0.53125 18/32 : 9/16 0.5625
19/32 0.59375 20/32 : 5/8 0.625
21/32 0.65625 22/32 : 11/16 0.6875
23/32 0.71875 24/32 : ¾ 0.75
25/32 0.78125 26/32 : 13/16 0.8125
27/32 0.84375 28/32 : 7/8 0.875
29/32 0.90625 30/32 : 15/16 0.9375
31/32 0.96875 32/32 : 1 1.0
I hope this helps you.

- RCT