Hi!
I require your help regarding a “challenge” I’m encountering.
Description: When configure to set in some position (Here in the video, 90°) ,the arm is bouncing. I can stop it by touching it, but I can also start it back bouncing. https://www.youtube.com/watch?v=HUyqkjhsG2g
Troubleshooting steps already taken: None 
Additional information: I’m wondering if it comes from this piece which is not installed correctly, and if so, is it possible to order it back?
Thank you so much in advance for your help!
@jmspaggi Ths behavior is not normal and as you indicated seems to come from the 805 servo in the shoulder. It seems that the issue can come from one of several places: bad signal; insufficient current; mechanical…
- Can you provide a clear photo of the SSC-32U and the connections to the board? Verify all connections between that servo and the board.
- Can you verify that the shoulder is free to rotate when it is not powered and the part you mentioned is not overtightened?
- Can you disconnect the last servo and see if the behavior continues (question of current).
- Disconnect all servos and reconnect only the 805BB to pin 0 on the SSC-32U and operate it using Lynxterm - does it produce the same issues?
Await your reply.
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Hi cbenson,
I think connection and signals are fine. I really suspect a mechanical challenge.
- Here is a picture of the board. I checked all connections. Because I can stop and start the bouncing with my hands makes me thing it’s not board related.
- The shoulder can move from 0° to about 135° with almost no resistance from the spring.
- I removed the “switch” on #15 and the wrist on #3 and got the same result. I can also reproduce that when then wrist is 0°
- Yes. In that configuration, obviously the elbow is moving based on the load, but I can still get the shoulder boucing.
I really suspect this part to be the issue => https://www.youtube.com/watch?v=nQgaSuIyE2M If you look closely, the top seems to be handling the move correctly, but the bottom seems to be a bit slack. Like if the screw was not installed correctly, or if I damaged it. Also, the nut there is a bit loos. Do you know if I can buy just this part with the 2 screws?
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Regarding (4), the role of those plastic parts is actually just spacers. The fact that the motion is not straight might mean that one of the main brackets connected to the 805 is not perfectly straight, or the horn on the 805 might not be straight. Can you check alignment around these areas? Try running the twisted RC cable below the servo as opposed to on the side? You are correct that the lower screw in that video doesn’t seem connected at all, though its purpose is largely served during assembly. Although we don’t sell just the spacers on their own, if that’s the cause of the issue, we’ll be happy to ship replacements out to you free of charge.
Does adding a bit of weight to the end of the arm (where the gripper would be) resolve the issue?
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