pic: Donut Grabbing Idea

Tis was a grabbing mechanism I designed the Saturday of kickoff. Unfortunately we won’t be building it, so I don’t get to see it in action :frowning:

It’s two pneumatic 4" cylinders that provide wrist and grabbing movement. It would be attached to the end of an arm. In the case of the overall design in my head, a telescoping arm with a 180 degree pivot, similar to one of the 60s robots from 2005 (66, I’m pretty sure, never found a picture of that robot). I did the fingers as tubes with triangles cut out, bent into shape and then welded. More complicated (and probably weaker) than simple bending with a tube bender, but pretty flipping sweet looking, as it looks more like the joints of your finguers. The curved bars between the front two prongs would ideally keep the donut from rotating in your grip.

Oh, and I did this with Solidworks (I’m a college freshman mentor, former student, for/of FRC Team 1015, PiHiSamurai)

The design looks very nice, sorry it didn’t get picked. I like the way you combined the wrist and gripping mechanisms. Did your team end up going with something simpler or with a different approach altogether? Oh, and how long did it take to CAD?


Sorry to threadjack, but how do you present it nicely like that?

is that part of 3dsmax, or an inventor feature?



The screenshot was taken in Solidworks regular work environment – there was nothing special done to render this shot.

The team is actually going with something similar. Instead of pneumatics, we’re using a threaded rod and globe motor for the grabbing, and we have wrist-like movement with a short third segment of the arm.

Ultimately it will be much less elegant, but simpler to make and repair.

Doing this design took maybe eight hours of work tops? During said time, I was IMing another college freshman mentor and I also made changes in various dimensions. (Originally I tried to do a 6" cylinder, but that was larger than needed, etc.) It was the only thing I did saturday after going to kickoff, and I touched up a couple things on sunday.

My team mostly calls them donuts. No one ever remembers to call them ringers.

Thanks for the feedback.:smiley:

I like it, not sure on how reliable that this may be, or how accurate, but I really like the fact that you can control the inner tube with little surface area on the object. If thought out correctly, machined, and executed I think that this may very well have a good shot at being one of the better arms out there. Very simple, low complexity design. What else would a good engineer want? Hopefully programming will not become an issue with this arm, but I do think that you did a great job not only thinking it up, but also designing it as well… so overall… Nice Job! P.S. Looks like the crane game…

Looks pretty nice. I’m not a fan of pneumatics so I like the fact you’re going with motors in the end. Hoepfuly it works as well as it looks.


Looks quite similar our current design concept, ours is sort of halfway between this one and the simpler motor actuated design. We’re planning on using a small cylinder for “claw” actuation and a motor for rotation via the “wrist” method.