Claw ideas (particularly materials and such)

[All Bones]

Alright, I've done most of the conceptual designs for the claw of our bot to grab the tubes this year and I've figured out a few things.

1. Optimal space in between the claw should be about 6.25 inches
2. The bottom part of the claw only has to be as long as the height of the tube(s)
3. Being able to hook under the tube then rotate the claw at the point where it meets the arm until it is above the tube and perpendicular to the tube will make it arguably easy(ier) to pick up tubes. Or you could just keep the claw pointed down as you drive but that would be boring.

And
4. Rubber bands and wood can easily grab the tubes by themselves if used with the 6.25" gap and step 2, so obviously not much power is needed

However we can't build a functional claw (well maybe functional but probably not practical) out of wood for the competition. What I was thinking was, where the two parts of the claw meet, it would be optimal to keep the bottom most part non-movable and put some kind of gear teeth on the inside edge of the top part, still where the claw meets the arm. Then just use a servo to spin a gear that will close the top part of the claw. We were also considering adding extra space to the top part in order to put in a kind of roller to manipulate the tubes vertically. Other then all that though, I'm not sure how to build it. Like what materials to use or how to attach it to the arm (which is not fully designed yet so please don't ask anything regarding that). Any suggestions would be appreciated.

[Bob Steele]

i might suggest that a fairly simple way to create a thicker jaw is to use two pieces of polycarbonate or aluminum or something fairly thin cut to the size you need. You can join them with spacers (or standoffs if you have them) this can make a nice thick creation out of a two dimensional piece.

it is kind of like extruding in inventor if you use that or any 3d program... the extrusion size is determined by the length of the spacers between... (held on by screws through the two "plates")

This method can really make something quickly and cheaply...and it is quite robust.

i wouldn't rule out a wooden jaw though... I don't see any reason that you couldn't make a jaw out of wood though... Remember that plywood is one of the first composites!!

I have seen many great designs done in wood... if you understand and use its properties and can deal with the weight to strength issues... it is a fine robot material...

We made a gripper in 2007 in the way I described above ... with the standoffs and polycarbonate... and used some simple aluminum bar stock for linkage and it worked great...

Good luck!!!

[All Bones]

Awesome, thanks. We managed to find the bottom part of our 2007 claw which was made pretty much the same way you just described, with two pieces seperated by . . . something, i wasn't on the team then, so I don't know. But it seems like this idea is going to come along nicely