Hello,
I'm building the robot arm with gripper featured on the How To Mechatronics site. I ordered the servo motors recommended on the site and have discovered the ones on Amazon are continuous vs. 180° rotation. The issue is with the MG996R servos. I ordered them from Amazon using the link from the site. I only realized it when the arms tried to move way beyond 180°. Just to confirm, the if the MG996R is the 180° is should have a physical stop. The ones I received do not have a stop.
Kyle
Please post links to the project you're building and the servo you bought.
But I'm confused. How did you discover that the arms moved "way beyond 180°" without physically testing them? If you have an Arduino and a 10K pot you can just run the Knob example program and it will be immediately evident which version you have.
Steve
Hi Steve,
Here is a link to the project:
Here is a link to the servos:
Attaching the arms first was my mistake. I had assembled the arms on the servo horns to test the mechanical fitup and then started testing them one at a time. As you mentioned, I have set up the control using 10K pots and have not yet started on the Bluetooth aspect of it. Also, when mapping out the pots to control the servos, I limited the angle of rotation of the servos. That's when I found they would travel outside what I had mapped and became concerned they were continuous rotation servos.
Kyle
Those are not genuine TowerPro MG996R servos they are clones. So they could be anything from excellent copies to cheap rubbish.
But if your test program moves them to positions where they stop then they're not continuous servos. A continuous/360 servo will just rotate continually and changes to the write() value changes direction and/or speed but not the position they stop at.
Steve
Hi Steve,
I think I'll pull the servos off and test them in an isolated condition on another breadboard. I have another arduino and can try that. My understanding was that a 180° servo will have a physical stop. I have a couple of micro servos - an SG90 and a KY66. One has a physical stop and one does not. I'll try them as well.
You're right about ordering parts from Amazon. You don't really know what you'll get sometimes.
Kyle
Well those pictures show the TowerPro name missing from the label that otherwise looks very similar to a real one. That's a bit of a give away.
Steve
There are a lot of no-name servos out there. I ordered a servo tester to check them out. I could run them with the arduino but the tester will be handy for other quick checks.
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