Phoxtane Posted September 21, 2011 Share Posted September 21, 2011 I\'m working on a project in Lego, but I need a 13:1 gear ratio to do so. That is, turn the output shaft once every time I turn the input shaft 13 times.Whoever can help me will get a mention in some video credits, if I make a video. I may end up not making one right away, or at all.Off-Topic: Never use the official Lego message boards for specific help like this. Evidently, nobody knows what I\'m talking about, because I have zero replies as opposed to some other threads up for less time than mine with poorly-worded questions.If you want to help me in the Lego message boards, my profile name is Starfox5678, and the thread should be in the Technic section near the top of the first page. Link to comment Share on other sites More sharing options...
HarvesteR Posted September 21, 2011 Share Posted September 21, 2011 Well, this is kinda hard without knowing the sizes of the gears in relation to one another... If I recall correctly, the big gear (about 1 inch in diameter) had a ratio of about 3:1 to the small gear (the ~1cm diameter one)... but I can\'t say that\'s accurate...I would suggest you take a marker, and put a small dot on two gears of different sizes. Place them against each other so that both dots are aligned, and turn one of them fully around the other, counting how many times the dot on the gear that\'s going around passes nearest the other gear. When you return to where you started (the dot on the other gear), you\'ll know more or less the ratio of their circumferences.Or, if you can measure the gears accurately enough, circumference = 2 * PI * radius. Another idea would be to count the number of teeth in the gears... assuming they\'re equally spaced so they mesh, you could get a rough estimate from the ratio of teeth between 2 gears.From there you\'ll have to do some math and/or trials... If the ratio of a big gear to a small one is, say, 3:1, you can connect a third, small gear to the same axle as the large gear, and mesh that with a big gear on yet another axle. That already puts you at 9:1... to get to 13:1 you\'ll probably need a large-ish combination of upshifts and downshifts, but that will depend very much on the ratio of the gears themselves, so I don\'t think I can be any more specific.best of luck with your project! (I really miss having my LEGOs around)Cheers Link to comment Share on other sites More sharing options...
ronnyfire Posted September 21, 2011 Share Posted September 21, 2011 http://myweb.cwpost.liu.edu/magot/classes/csc/RobotFundamentals/downloads/gears_drivetrain.htmThat has a few images showing the gear ratios, ill see if i can find a combo for 13:1How close to 13:1 does it have to be? xD Link to comment Share on other sites More sharing options...
Sordid Posted September 21, 2011 Share Posted September 21, 2011 http://myweb.cwpost.liu.edu/magot/classes/csc/RobotFundamentals/downloads/gears_drivetrain.htmThat has a few images showing the gear ratiosBetter: http://gears.sariel.pl/On a tangentially related note: http://www.ted.com/talks/arthur_ganson_makes_moving_sculpture.html (skip to 8:20 if you\'re not interested in various non-gear-related contraptions) Link to comment Share on other sites More sharing options...
Guest LoSboccacc Posted September 21, 2011 Share Posted September 21, 2011 using the calculator ( http://gears.sariel.pl/ )and an idea I\'ve read from the internet (it was used for replicating a clock of sort):create a combo giving a 6:1 ratio.create a combo giving a 20:1 ratio.(I did it but I cannot link them, I\'ll attach some screenshot)pick a differential: one axle input of the differential should be driven the 20:1 combo; the other axle should be driven from the 6:1 combo. both of those should start from the same axle.given all the constraint, the differential could only spin at an average of the given axle inputs, that is, 13:1I repeat so to make it clear: I was not the originator of this idea, I deserve no credits. place your credits where it\'s due (a mix of google and the internets, probably) Link to comment Share on other sites More sharing options...
Phoxtane Posted September 21, 2011 Author Share Posted September 21, 2011 Great work!Yeah, I found the calculator online, but it doesn\'t tell you how to get to a 13:1, it just tells you what the current ratio in your train is. I\'ve also contacted Sariel himself on this matter also.The differential idea seems the most likely solution. I\'ll give it a try after school today.UPDATE: How it\'s going to work, hopefully...The 6:1 ratio and the 20:1 ratio will use the same input shaft, and will use a differential to average out the rotations to get 13:1.I need another 20:1 ratio for the other part of the Tzolkin, so I\'ll just reuse the 20:1 ratio, and perhaps even use the same shafts. Link to comment Share on other sites More sharing options...
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