Here’s a little sketch of the original idea for the Mega Claw. Build a big frame, make a slide go back and forth left and right and drop a claw. Easy right?
We created a 3D concept and we figured 2×3 are only $2 each so it would be perfect. When we got to the hardware store we noticed that they were bulky and unfortunately a lot of them were twisted and warped. It would make it hard to design a modular system around those. Plus with the variation in material we needed to double everything up to make it strong enough. Eventually we gave in and decided to get a off the shelf canopy. It was faster to setup and only 1×1x4 when folded. Definitely made it easier to transport.
We need to have a total of 4 motors; x,y,z, and claw. We thought about buying large motors but then we would need adapters for the shaft and they were pretty expensive. We finally settled on using battery powered harbor freight drills, They were rated to go at 900 rpm on 18V so we figured on 6-12V they should be slow enough for the machine. If they weren’t we could possibly gear it down, or use smaller pulleys. The best part was the drills come with a chuck and a gear train so we get massive torque and a coupler for only $20-30 each.
A picture of how we attached the drill to the main shafts. The pulleys in this picture were made from a makerbot 3d printer. This component is the winch that raises and lowers the claw.
For the slides we had a pulley system similar to a clothesline. We had a sliding block that was pulled by two strings. Skate bearings on the block made it glide effortlessly.
In this concept we had the pulleys sideways, being off center the block would fall off the rail a lot. Also we only have it anchored to the top so the entire assembly would tip over when the slide wasn’t in the center.
We realized early on we would need something to detect when the machine reached the end. We created these bumpers at the end that would hit a button or a reed switch (a magnetic sensor). In the final design we used a reed switch.
For the claw concept we didn’t bother with a 3D model first. We took out the Lego bricks and assembled what you see in the .gif above. It worked so well we simply redrew it to scale, added a third arm and scaled it up.
More videos and design ahead–>
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