Hi wise and powerful council of arduinonians.
I am working on a project that utilizes dozens of servos. Because i need so many, I use the cheap tower pro
Unfortunately the keep breaking. It seems that the gears are jammed. Does anyone know what causes them to jam and how to avoid this? If the only answer is you get what you paid for, do you know of any servos that are high quality and fairly cheap (under $10)?
Do you have enough torque ? So it is only the nylon gears that jam ?
Servos with metal gears are more expensive, and I don't know what kind of special things you do with them. Perhaps you can reduce the mechanical stress by programming a slow start of the rotation in your sketch.
Have a look at the website of www.sparkfun.com and www.adafruit.com
Search for 'servo'. Those shops have a selection of good products.
Or do as I do, buy many servo motors and let them run for days to see which one is okay.
I have used servos from here:
You have to consider what torque need of course.
The "economy" 9g servos have weak gears that will strip if pushed against the internal hard stops or rotated by hand. The HXT900 is reported to be more robust. You need to test each servo to find the rotation limits and then not exceed those limits.
I opened up my Hitec HS-85BB+ servo. It was the tenth one I'd broken.
There are three pins holding the gears onto the housing. The pins are seated in tiny plastic holes, which are part of the plastic housing shell of the servo. When there is resistance on the servo to a point beyond maximum hold torque, these holes holding the pins in place are the weakest link and are the first things to break.
Now one of the three columns of gears are at an angle to the others. This is usually the middle pin of the three gear columns, because one is going into a deep motor hole, and the other is firmly connected to the potentiometer. This leaves the middle one, now with a less than round tiny hole to try to keep a round pin secure in it. As the plastic is now warped, the pin will never be secure again.
If you want to fix it NOW, try to melt the plastic around the middle pin with a hot screwdriver while ensuring you don't create any lumps. This will make the plastic hole fit snug around the pin again. If you have time, buy servos that are rated to have higher holding torque, especially if you keep ripping the housing apart with too much force. I would like for the holes that hold the pins to be made a lot better, but I think nearly all hobby servos have fragile gears precariously balancing on tiny pins with nothing locking the pins in place whatsoever. Therefore, buy servos with more torque so that you can simply trust that the manufacturer already tested these new servos you're gonna buy to withhold more resistance than your broken ones.
with nothing locking the pins in place whatsoever.
I've taken a lot of servos apart and the gear pins I have seen have seating holes in both the servo body under the gears and in the top of the servo above the gears.