Servo not holding / moving on it's own

Just finished building the AL5D robotic arm with the rotating vacuum gripper attachment for a work projects. There seems to be a problem with the “ellbow” servo.

  • When left stationary for a few minutes, the arm tends to droop down own it’s own, even so the robot is still powered. This is with nothing loaded onto the robot and no major extension, just the arm at 90degrees.

  • Sometimes that servo moves (powered) on it’s own when other servos are moved.

Is this a bad servo?

Bonus question:

  • The “shoulder” servo (the one right on top of the rotating base) seems to buzz, even with no load. Anything we can do about that?

Btw. we don’t have the springs attached since we don’t plan on lifting anything heavy and the springs seemed way too taught and pull the robot back against the power of the servos.

Thanks for your help!

You can post some images so we can look for jumper, wiring, or assembly issues. The springs are used to counteract the weight of the arm, not necessarily just the payload although it does that too. So does the entire arm go limp, or just one servo? If it’s the entire arm then you probably have the jumper VS1=VL installed. Remove that jumper and install a fresh 9vdc battery. I would have to see the servo moving when it’s not supposed to to really know what is going on.

The servos are not silent when operating. There isn’t anything that can be done about that.

Thank you, that did indeed fix it.

We are using the arm including the rotating vacuum gripper for automated testing in our company and it’s working well so far. The rotating vacuum attachment is a very nice touch - well done.

Btw. there are no instructions for building it online (as far as i could tell). Just a heads-up.

After seeing the robot in action here at work, I might buy one for myself just for fun :smiley:

Thanks for the nice words. Sorry there is a guide but the link is on the product page. We will add it to the Assembly guides page Monday. For now here is the link.
lynxmotion.com/images/html/build176.htm

We’ll keep one on the shelf for ya. :slight_smile: