Monday, August 16, 2010

Automated K'nex Ball Lift

I've been trying to come up with a new design for a k'nex ball lift that HASN'T been done by shadowman already.... so here it is. By combining lego and k'nex pieces I have constructed a fully automated robotic ball lift. The machine uses the ultrasonic sensor to wait for a ball to reach the bottom, where it is then picked up by the robotic claw and brought up a ramp to the top. This is just a prototype of the machine now. I am expecting the final to have a 5-6 foot long lift hill, and I have no plans to integrate this into my current work in progress ball machine.

Saturday, August 14, 2010

K'nex "Leave Me Alone" Box

I actually finished this last week, I just now got around to making a video....

Thursday, August 5, 2010

K'nex "Leave Me Alone" machine - work in progress.

I have seen tons of videos of "leave me alone" boxes around, and I decided to make my own. I know basically nothing about electronics, so I am attempting to build a 100% mechanical one. This machine is powered by the DC motor, which constantly spins in one direction, even when the machine is not in use. the starting and stopping, and the switching directions is all done mechanically, and I did not "cheat" by making the arm on a reciprocating axle that automatically retracts it regardless of the position of the switch.

Anyway, I designed and built this fully working prototype in about 4 hours from about 300 pieces. I plan to encase it in a box in the next day or two, and I will post a video then. This machine is a close runner-up to my automatic transmission as the most complex mechanical device I have ever built with K'nex.

How it Works - WARNING: TL;DR

I will try to explain this as well as I can for the 2 or 3 people who actually care. The blue lever on the far left is the "switch" which turns the machine on or off. When the switch is pulled, a series of needlessly complex linkages cause 2 things to happen. One: the transmission in the center of the device (an extremely downsized, re-designed version of the one found in my automatic transmission) is switched in to the "forward" position. Two: the "clutch" is engaged, by pulling the red gear farthest to the right into position so it meshes with the gear coming off the motor, as well as the drive gear for the rest of the machine. 12 gears later, the large L-shaped arm in the center of the device swings forward and hits the switch. Due to the design of the linkages, this only switches the transmission, but does not disengage the clutch. The transmission reversed, the arm goes back into its resting state. At the end, it engages a rod which slides the clutch gear out of position, stopping the machine in its starting point. (hopefully this will be made clear by a video, maybe...)

Wednesday, August 4, 2010

K'nex Windmill

Still out of ideas for my ball machine, I constructed this K'nex windmill in about 2 hours yesterday. It stands 9 feet tall and uses about 700 pieces. The thing that separates this windmill from my previous attempts (which I did not post on the blog) and others that I have seen is that it uses no non-k'nex pieces. The blades are made from 20 k'nex panels, which seem to give me the best weight-to-wind-resistance ratio. Though they are full of small holes, the wind still catches the blades pretty well.

The windmill will turn steadily in winds as low as 3 miles per hour, and can easily reach 60 RPM on a normal day. The shaft of the windmill is connected to a small gearbox, which generates a surprisingly large amount of torque. I may even end up powering a small mechanical device with this if I feel up to it.

The blades of the windmill are about 1.25 feet long, and it sits atop an 8 foot tall tower which is stabilized at its base by 4 bricks.