First, adjust your tension mechanism so that it is about 1/3 of the way from the closed position. Then measure the diameter of your wheels where the blade rides. Take each wheels diameter multiply that by Pi (3.1416) and divide it by the number of wheels.
Then add these numbers together. Example:
14” wheel 1
12” wheel2
14 (3.1416) /2 =21.992
12 (3.1416)/2 =18.84
21.98 + 18.84 = 40.82
Now measure between the axles on which your wheels turn. If you have 2 wheel use this number twice. If you have more than two wheel measure from axle to axle until you return to original axle. Example 36” axle to axle so 36 x 2 = 72
Then you add your axle dimension to your wheel dimension 72 + 40.82 = 112.82”
So your blade length would be 112.82” or 9’ 4 13/16”
By: Dennis Zimmerman