Monday, April 22, 2013

Some success

This weekend I took a loooong drive in search of snow. I had busted my ass every night this past week to get my V2 prototype built so I could test it Saturday. I worked out as many bugs in the system as I could prior to driving up to the snow. I also brought all of my tools with me. I got there, and had to do some work to strengthen one of the paddles which was too fragile. The fix worked great. Upon the first test, I found that under resistance the paddles pushed closer to the board by a half inch, and the paddle's teeth actually became snagged on the rear end of the board preventing them from spinning. The intense torque caused the weakest link in the system to fail... The gear box. One of the gears pretty much shredded. I adjusted the device position so it couldn't snag the rear of the board but the damage had been done. However there was some success. Even with the shredded gear tips, it was able to get traction, and move a rider on the board. The biggest unknown in the design was whether I could keep traction. The rest can now be engineered to perfection. I have determined that I need a better way to test the device. If each iteration takes 12 hours to test, I will never finish this thing. I am looking into buying/renting a wood chipper. I figure I can put many bags of ice through the wood chipper to create a snow like consistency in my back yard. This should allow me to rapidly iterate at home where I can print new parts, test them, and work out the bugs quickly.
Some other lessons were learned. A spring (not pictured) works great to keep the device retracted. The board is easy to carry around like a normal snowboard. The device does not get in the way in any way, shape, or form. Once deployed it stays deployed. If traction is a problem, the pull strap works great to dig the teeth deeper into the snow. The strap is not a good way of deploying the paddles into the snow. Manually pushing them down works much better. Perhaps with a better design the strap could be more effective. The weakest link is in fact the gearbox. My plan is to make a mold, and cast gears twice as thick (1" thick) in a mixture of the hardest resin I can buy, mixed with small fibers. I think it would also be wise to bring a spare of each part. Another lesson learned is that the mounting system where you remove the binding, and slide the plate under the binding, and strap it down (as pictured) is not a good system. The firmer you keep everything mounted to the board the better. Any give in the system has negative results. I ended up just epoxying the device to the board, and was very happy with the results. Although it will not be easily removed. Perhaps I can epoxy some sort of mount, which the device latches onto instead. V3 will be very similar to V2 with a few tweaks to make everything more practical. I also think some work is needed to achieve my stretch goal of being able to drive this thing up a 20 degree slope.

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