Wheel driven stop mechanism design
 

Dear CD,

We've gone down the path of the Boom Done design with a wheel-driven, ball hoop shooter. I'm not sure how to tackle the stopping mechanism for the thrower. What methods have you used that you found successful?

Off hand I can think of a couple of designs

1) 1/8 inch wire cable attached to the frame and throwing arm to limit movement.

2) Some kind of mechanical linkage attached to the throwing arm sprocket.

3) ???

Regards,

Re: Wheel driven stop mechanism design
 

Some sort of strong cable should work. Or just a bar that the catapult itself hits, although that might be harder to make structurally sound because it is higher up. Also, using the cable has the added benefit of being able to adjust when the catapult hits the hard stop fairly easily.

I would also recommend using a potentiometer to stop the catapult in code. Not only will this reduce the wear on your robot, but you could actually use it to adjust the release angle of your shot. This should only supplement a hard stop, not replace it, because I can almost guarantee that something will go wrong with the code at some point.

Re: Wheel driven stop mechanism design
 

You could also find a way to attach a limit switch to the shooter arms.

Re: Wheel driven stop mechanism design
 

Agreeing with Pault, I'd recommend an actual structure in addition to a stop in the coding, like a bar or peg. Definitely make it durable, as it will take a lot of abuse from the force of the thrower.