Often used for crawlers (steering), helicopters (cyclic), and model airplanes (throttle, aileron, elevators, and flaps), this servo arm is CNC machined from a solid billet of 6061-T6 aircraft aluminum. Working to its strengths, it's slender vs. bulky to optimize strength at the expense of mass (less bulk means less force wasted accelerating dead weight). Have you ever heard how cars are designed with crumple zones to protect occupants? This ProModeler servo arm is similarly designed, e.g. the idea is to fail the M2 mounting bolt securing the control ball. Basically, it works like a mechanical-fuse to protect the servo itself.
Especially nice is the sacrificial part (the screw) is cheaper than destroying a servo due to a sharp impact (plus it's easy to replace and spares don't take up much room). Another nifty thing about this ProModeler servo arm is the torque factors laser etched at the mounting holes.
For this temp-one, the aluminum is tapped M2 at 10, 15, and 20mm and etched with 2.5X, 1.7X, and 1.3X, respectively. When installed on, for example a 630 oz-in servo, the math works out like this: 630oz-inx2.5-$2-$2=1575oz÷16oz/lbs=98.43lbs
- 10mm = ~100lbs (98.4lbs)
- 15mm = ~70lbs (67.9lbs)
- 20mm = ~50lbs (51.2lbs)
It fits any servo you wish to protect equipped with ProModeler-compatible 25T-splines.