Motor turns tables are limited to the lengths and cross sections listed. Those of us who cut and strip rubber to other than standard size need something more general.
I use a formula.
Caution; the breaking turns are affected by many things. Every batch of rubber has different properties, warmer temperature stresses the rubber, lubrication, stretching, rate of winding, cooling, previous stretching, braiding, contamination and other things affect how many turns a motor will take. Winding heats the rubber, it heats faster as torque increases and every turn puts in more work. Slow your winding as you get close to full to let it dissipate the heat.
Formulas can be a useful guide to winding under standardized conditions.
My formula is:
T = 10.64/Sqrt(S)
T is breaking turns per inch. Multiply that by the length of your motor to get breaking turns for that motor.
S is motor cross section in square inches. Multiply strip thickness (0.042″) by motor width times number of strands.
Sqrt( ) is square root. Look on your pocket calculator. Most computers have a calculator window.
10.64 is an empirical coefficient. It is the result of testing some pretty good Tan II. Lou got exactly the same for some Tan SS. Purely coincidence.
You can establish your own formula by winding a short test motor under standard conditions and using the formula to calculate a new coefficient. “Good” rubber will run from 9 to 13.
Here is an example of a turns table I made up for a motor.
Denny Dart II, 7″ NP Prop, 17″ loop of 0.083″, 127.4 tpi
% Breaking Turns Number
If you are using a 15:1 winder, divide those turn numbers by 15 to get the number of cranks on the winder.