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How can I make to arms move towards each other with high precision and a single motor?

What I would like to do is have two "arms" side by side both starting at 90 degrees (Figure A), and then have them pivot inward until they touch at the tip (Figure B), but I need to be able to precisely control their angles, use a single motor, and the base of the "arms" cannot move. Does anyone know of a way this can be done?

Picture of How can I make to arms move towards each other with high precision and a single motor?
mpilchfamily8 months ago
Use a stepper motor and there are many many ways to use a single motor to control 2 arms like you want. Play around with some straws and see what you can come up with.
Something for you to play with. Extend the end of your arms with an 'L' shape past the pivot point. Leave the joint in the L on a hinge. The motor will need a disk attach to the shaft for the ends of the 'L' to attach to. When the disk rotates 90 degrees the arms will open and close. Attached are a couple of very basic images to give you an idea of how it will work. The pivot point will be somewhere along the long part of the arm.
arms1.jpgarm2.jpg
geekman2 (author)  mpilchfamily8 months ago
Yeah, that's what I was thinking of doing.
steveastrouk8 months ago
Just put a couple of meshed gears at the ends.
iceng8 months ago
Twin worm gears are a marvelous solution for a single motor.
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