Testing servo torque

[Smokin Joe]

I have a box of unused Futaba and other servos. I also just picked up a digital pull meter that measures in oz, kg and lb.

With the knowledge of the members on this forum, I'm looking for input on what pull amount is good using a 1/2" horn to know if I can use these in my builds. Thanks, Joe

[fhhhstix]

Make it easy on your self and look them up on the web then you can make a list and rank them in order of the amount of power they have. Then you will have an idea of what they would be suitable for. You can also put up a list here of what you have and members can give feedback on any they have used.

Travis

[Espeefan]

If you've got some older servos, you might not find the specs online. In that case, you might have no choice but to test the torque yourself. I think the standard for measureing the torque is to use an arm that hooks to your strain gauge exactly 1" away from the center of the output shaft.

What's a good torque strength? That depends on what you want to use the servo for. For shifting a transmission, you don't need much. Just about any standard servo will handle that job. Even the cheapest ones can do it without a struggle. For steering, you'll need a little more torque.

[Izzy]

Oz-in is torque - measured as a force at a distance (perpendicular distance of force to the point of pivot)

So if you have a rating as 100 oz-in and your testing with a servo horn pivot point 1/2" from center then your scale should hit around 200 oz. Conversely if you horn was 2" then your reading would be 50 on the device.

Something else to remember is the idea of safety factor. Even though it may put out 200 they may only rate it at 150 so it will perform well for a longer time. Whereas a lesser company might rate it at 185 thinking that you won't try to go too far. There are very few instances of design safety factors for products. Those that do exist are primarily things like military related and measuring devices.

[Smokin Joe]

Originally Posted by Espeefan

If you've got some older servos, you might not find the specs online. In that case, you might have no choice but to test the torque yourself. I think the standard for measureing the torque is to use an arm that hooks to your strain gauge exactly 1" away from the center of the output shaft.

What's a good torque strength? That depends on what you want to use the servo for. For shifting a transmission, you don't need much. Just about any standard servo will handle that job. Even the cheapest ones can do it without a struggle. For steering, you'll need a little more torque.

Thank you for your help. Joe

[Smokin Joe]

Originally Posted by Izzy

Oz-in is torque - measured as a force at a distance (perpendicular distance of force to the point of pivot)

So if you have a rating as 100 oz-in and your testing with a servo horn pivot point 1/2" from center then your scale should hit around 200 oz. Conversely if you horn was 2" then your reading would be 50 on the device.

Something else to remember is the idea of safety factor. Even though it may put out 200 they may only rate it at 150 so it will perform well for a longer time. Whereas a lesser company might rate it at 185 thinking that you won't try to go too far. There are very few instances of design safety factors for products. Those that do exist are primarily things like military related and measuring devices.

Thanks for the tech. info. Everything I have is military calibrated thanks to my 22 yrs in the Navy. Contacts do help! Joe