Graduation exhibition HKU fine art 2013

Attempt #2

Attempt #2

Attempt #2

Attempt #2

Attempt #2

Attempt #2

Attempt #2

Attempt #2

Attempt #2

Attempt #2

Attempt #2

After coming really close to a working machine on attempt#1 I took a gamble and made a entire new work for my graduation exhibition. The mayor problem in attempt#1 was the friction in the wood on wood sliding mechanism. For the small version it wasn’t a big issue but any more weight and it would stop working. So I went back to the drawing table and took 1 week to redesign my machine. I ended up with using lead screws and electric motors for the drive mechanism and linear guides for support.

The construction is made of meranti wood,welded steel and teflon bushings. In total there are 64 connection pieces, 64 bolts, 400 washers, 8 1×1 meter frames, 8 DC gearhead motors, 16 ball bearings and 8 14×4 leadscrews and nuts.

Being quite a novice in woodworking I thought my main challenge would lie in the contruction itself but in the end the electronics gave me the most problems. I made a custom circuitboard with L293D motor drivers and a teensy microcontroller. The motors were rated for 250mA, well within the margins of the L293D. But with all the added weight the startupcurrent would peak at 2A, making my entire custom circuit release the “magic smoke” and it was back to the drawing board. I ended up recycling the sinewave generator from attempt#1 and added a row of DPDT switches to make the entire control part elektromechanical. A much better option than the fragile electronics so in the end it turned out pretty nice. Unfortunately the graduation exhibition is a pretty harsch deadline and the total buildtime of 3 weeks just wasn’t enough to get it working. Currently the main problems are the battery and motors, check back in for attempt#3 wich is hopefully succesfull.