Using The control Rod Rigger to set up a control rod to  an exact length requires a caliper or some other measuring device which can measure the length required.

    1.    Measure the  diameter of the stud on the Control Rod Rigger.
    2.    Add that dimension to the center to center  distance required. (assuming both rod ends are the same size) (See below for different size ends)
    3.    Using the caliper (for example) set the outside measure of caliper to the dimension found above in No. 2  and lock the caliper.
    4.    Adjust the thumb screws of the Control Rod Rigger so that the proper dimension of the two studs fit inside the caliper. 

You now have the exact (within tolerance) center to center dimension you want.  Note that there is at least 3x the normal measurement tolerance involved here
because there are 3 measurements required.  Take extreme care in measurement as the errors will compound. 


If the control rod has different size rod ends or perhaps a clevis of a different size on one end use the procedure below.

    1.     Measure the diameters of the studs for each size.
    2.    Add 1/2 the dimension of each diameter to the center to center distance required. 
    3.    Using the caliper (for example) set the outside measure of caliper to the dimension found above in No. 2  and lock the caliper.
    4.    Adjust the thumb screws of the Control Rod Rigger so that the proper dimension of the two studs fit inside the caliper. 


You now have the exact center to center  (within tolerance) dimension you want. Note that there is at least 4x the normal measurement tolerance involved here
because there are 4 measurements required.  Take extreme care in measurement as the errors will compound.