I've bought a floppy fish toy (crab version) for my kid. The toy looks like:

enter image description here

Unfortunately, the toy mechanism inside jams when grabbed and the battery lasts for a short time:


I tried to do my own mechanism, printing own case and using Arduino with servo PowerHD R12 but the servo was heating up :( Is there any possibility to make similar mechanism for toy with not oversizing it? What kind of motor/mechanism would be good for that kind of sweeping toy so it doesn't get hot?

EDIT: what type of motor/servo would fit for this kind of mechanism? I tried few servos and notices that desired speed would be minimaly 0,06 [s/60sec] and momentum 8 [kg*cm].

  • 1
    $\begingroup$ funny looking kid $\endgroup$
    – jsotola
    Commented Oct 20, 2022 at 15:25
  • $\begingroup$ but it was heating up ... what is heating up $\endgroup$
    – jsotola
    Commented Oct 20, 2022 at 15:28
  • $\begingroup$ Welcome to Robotics Kuba, but I'm afraid that Unbounded Design Questions are off-topic because there are many ways to solve any given design problem. We prefer practical, answerable questions based on actual problems that you face, so questions which ask for a list of approaches or a subjective recommendation on a method (for how to build something, how to accomplish something, what something is capable of, etc.) are off-topic. Please take a look at How to Ask & tour for more information on how stack exchange works. $\endgroup$
    – Chuck
    Commented Oct 20, 2022 at 16:47
  • $\begingroup$ You could look at compliant actuators, which for a toy would probably just reduce to adding a spring between the tail post and the servo, but you need to keep in mind that applying resistance to the tail is going to increase the load on the servo, which is going to cause it to heat up. Maybe you could mount the tail on a shaft and create a magnetic clutch? Lots of possibilities here, but I think you're going to find it very difficult to fit everything in such a small footprint. $\endgroup$
    – Chuck
    Commented Oct 20, 2022 at 16:50
  • $\begingroup$ Hi, i added more specific information in my post so I hope this will meet the requirements. Im just looking for a good approach because my was not working best. I would like to get a better result. For problem with heating of servo - I coded it so it should slow down after 3 minutes and it helped lighty. Im not familiar with compilant motors, the idea looks fitting my problem - maybe it would be better. Is there any plug and play option for this motors or should I do it by myself? Scaling is the big challenge here. $\endgroup$
    – SKJQ
    Commented Oct 21, 2022 at 16:46


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