An Improved Servo Mounting Technique with the co-design of Craig Bisgeier of the Housatonic RR
Craig has been using the small blue servos to control his Fast Track solid-rail point turnounts using the direct-drive mounting method. While this has worked he didn't like the noise the servos were making. What was needed was a way to give the servo some mechanical advantage and to allow them to move to the endpoints and to "latch" at the endpoints so the servo wasn't continuously being forced out of position. After a few trial designs Craig and I came up with the mount in the picture. You can find more details of how Craig has been using this mount at the link above. Craig is having some plastic holders cast for him to convert his servos over. You can also easily fashion a mount of your own with blocks of wood or styrene. The key is to add a fulcrum plate at the bottom of the sub-roadbed to give the servo a longer lever arm to push against the stiffer solid points with. Also note how the servo horn is moving in the perpendicular plane which prevents the wire from moving in the up and down direction and poking up out of the hole in the throwbar.
Files for 3D-Printed Servo Mounts with this geometry are available in this zip file
TVD_TP3srvMnt_v3.stl. Micro Bracket. Made to minimum possible size for SG90 type servos. Because only one screw is used you should also glue the servo in place with thick CA.
With servo and .031" spring wire attached.
With snap switch (Digi-key EG4542-ND) CA'd in place and 2 5/16" screws (microfasteners.com LPP0205) to align
Other Servo Mounts
Top of Layout using an Upside-Down Servo in a SwitchWright Bracket Note the use of bends in the driving wire to allow some spring in the drive. Makes servicing and mounting simpler.
Especially nice for hidden trackage.
Side Mount using L-brackets
Again, bends in the wire give some spring. You can fine tune the position by re-positioning the servo arm on the servo drive gear. L-brackets are available on the Dual 3-Way page.
