So I designed the real claw in Google Sketchup, a 3d design tool. I decided to make it out of 1/4in plywood and to add a skate bearing at every joint to reduce any friction or strain on the motor. In hindsight this cost a lot more and probably wasn’t necessary.
We printed out all the patterns and cut them all out using a band saw.
With the right motivation and sanding it all fit like a dream.
I found a site called www.gifninja.com and got a little obsessed with making animated gifs.
Oh well it was time to disassemble the claw and peel off all the paper to paint it. Look at all those skate bearings. By the way those aren’t bolts, those are all rods we cut and sanded to the right length.
3 Coats later
I cheated and used a drill to power the claw in that video, but explaining how it works is a lot easier after you’ve seen the video.
The claw has a little winch inside. There are three Kevlar ropes inside that lift the three claw teeth and make the claw close. The two chords on the outside are used to make the claw open. The outside and inside are wound in opposite directions so one pulls and the other releases. A pulley connects to the motor.
This is a shot of the three chords that pull the claw closed. Using three helps the claw’s finger close at the same time. Some springs were added so the pieces wouldn’t slam so hard together.
Threaded rod was machined flat on a grind wheel and drilled so the ropes would not chafe
Pulleys made from plywood
We always wanted to use a pneumatic piston, but the cost of the air cylinder, 20 feet of tubing and everything else made it too expensive. Maybe next year.
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