Hi,
I need to setup a rig to test potentiometers. I need a servo that will travel from 0-300 degrees for over 100k cycles. Do you have a digital servo that will accommodate this travel or will I have to use a gearbox? Would a stepper motor be more appropriate?
Thanks,
Ray
100k cycles will likely be the issue for an RC servo, as well as for many hobby-grade parts. We do have a number of RC servos which have 300+ degrees of travel, though almost all have a duty cycle over around 25%, meaning they cannot be used continuously for stress tests. You might want a brushless DC motor (or AC though we do not carry any), and a 4-bar mechanism which gives you the appropriate angle of travel (custom built). The higher the efficiency of the motor, the less it will heat up and the longer it will last.
Thanks for your quick reply. I have looked at quite a few different options, now including the 4-bar mechanism. The issue that I have with some of these options is that they apply too much or too little torque, or forces that the test object might not otherwise see (such as a side load). Setup time and unknown torque values are why I think a direct coupled setup is best.
I’m not restricted for time for this test, so I can add a delay in my code to achieve a 25% duty cycle. Also, it wouldn’t be a big deal to replace a servo if it failed. I’m assuming I should be able to get at least 25k cycles out of a metal gear servo.
I found the Hitec HS-785HB on your website. Do you think this would be a good start or do you have something that might better suit my needs?
The 785HB also came to mind since it is quarter scale, can rotate the angle you want and is easy to control. Our hesitation is the number of cycles given that it’s “raison d’être” was for use in hobby RC sailboats as a winch servo. A stepper would likely be more appropriate - you can connect it to an Arduino-compatible stepper motor controller shield and an Arduino. You would program the Arduino to control the stepper motor as you wish (complete with delays) and can also add sensors to see if the motor is overheating, actually rotating etc. Stepper motors are inexpensive enough that if one breaks after n cycles, you can have some spares ready to go.
robotshop.com/en/arduino-mic … oller.html
robotshop.com/en/arduino-shields.html
robotshop.com/en/stepper-mot … llers.html
