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Make Your Own Servo Linkages
They will be stronger and look better ---- and the cost is the best news
GENERAL - In larger aircraft it is common to buy links pre-made, and they can be very pricy. The requirements are really not complicated.
Must be strong in push and pull directions - just can not ever fail
Can not flex at any time for any reason
Must mate up to available ball links and other hardware
DESCRIPTION - My links are made from 4-40 threaded rod and they have a carbon fiber tube over the rod. This satisfies all three requirements. With a little practice and some of the right materials, you can have links that look great and perform better than any commercial rods.
STEPS TO MAKE THE LINKS
FIRST -- mount the servo and the control horn. Take care that the servo arm and the linkage are not forming a 90 degree angle when the servo is centered. This creates the chance for the arm to bind up at one extreme of the throw.
SECOND -- power up the servo.. Set the transmitter for centered trim, 140 end point adjustment, and no sub trim. ( zero all controls)
THIRD -- set the surface in a centered position and clamp it in place.
FOURTH -- attach the ball joint to the servo arm and the connector to whatever kind of control horn you are using.
FIFTH -- measure the length from the end of the threaded area of the ball joint to the beginning of the threads to the control horn end. Cut the 4-40 threaded rod to that length.
SIXTH -- cut the carbon fiber tube to about 3/8” shorter than the rod.
SEVENTH -- assemble the rod to the two ends with the tube over the rod and adjust the length to center the surface. (The tube is now loose over the rod)
EIGHTH -- center the tube and put a single drop of fast CA on each end and shoot it with accelerator to be sure the CA will not flow into any of the fittings. This will hold the tube in the center of the rod and prevent any bending or flexing in the rod.
You now have links that really fit and will never let you down. The cost is a laugher compared to the purchased ones.
The titanium rods are expensive and they are great equipment. They are turnbuckles and allow for adjustment of the length of the rod by turning the center. This is handy except that I do not adjust the length after the setup of the plane. Do you?
The commercial c/f rods are expensive and some are junk. The lower quality ones do not have a continuous rod in the center, but have the c/f tube glued on to metal ends. These will fail with time and should be avoided at all cost (even though they have high cost.) (Ironic isn’t it?)
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