Guzunty Pi robot neck / head assembly notes

Now I am assembling the robot neck which consists of 2 servos, one to turn the head left / right, the other servo up / down.

One thing I am not sure is how to fix the 3mm bearing.  The fixing now seems too have too high fiction and I worry that I would burn the expensive (RMB50~70) TowerPro MG996 servo if it got stuck.

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