Sawppy Servo Experiment: Standard Servo with Metal Horn

From birth my Sawppy has been running around with LX-16A servos made by LewanSoul (also seen sold under the Hiwonder brand *) but that is not an explicit requirement. From the onset I designed Sawppy to accommodate multiple different servo types, primarily the three I investigated. In theory any servo would work, as long as they physically fit within the available space and someone puts in the effort to design a servo-specific mounting bracket and output adapter.

In an exploration to lower cost of rover building, today’s experiment is to validate my design goal of flexibility, putting theory into practice by adapting standard RC servos. This servo was also interesting because it has a metal horn, which would replace the common plastic servo horns that have been a common point of failure. This particular pairing of servo and horn came from now-defunct Roboterra (as of writing, the link shows up as a Squarespace site whose subscription has expired.) But the same concepts should apply to other servos and their horns.

Roboterra servo with metal horn

An adapter bracket was quickly whipped up to bolt to Sawppy. The bracket surrounds the entire perimeter of the servo including the four empty mounting points. The servo is not mounted as RC servos usually are, because Sawppy was designed so the servo only needs to provide twisting force. They are free to slide along axis of rotation, letting 608 bearings built elsewhere into Sawppy take care of handling the forces of a rover on the move.

Roboterra servo bracket and coupler

The metal horn on this servo is much larger in diameter than LX-16A servos, allowing a larger 3D-printed coupler. The metal horn was tapped to accept screws with M3 thread. The larger coupler held with M3 machine screws is far more sturdy than the LX-16A solution of coarse threads cut by self-tapping screws.

This is a promising first step into using commodity RC servos on a rover build. A large selection of RC servos are out there for every budget and power, making them a tempting option for some rover builders. But there’s still work ahead as the wiring will get more complicated as well as requiring a revamp of the electronics control system.

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