Posted January 29, 20205 yr Hi Everyone, I have made a video about creating a 7:1 gear ratio mechanism using just 2:1, 3:1 and 5:1 gears. No 28 teeth gears used. Youtube subscriptions appreciated! Kind Regards and keep building, Rob
January 31, 20205 yr Author Hi Just an update...someone on reddit posted that you can create an exact 7:1 using a differential with 1:5, and 1:9 input to create a 1:7.
January 31, 20205 yr Problem solving is a key part of technic.. quite often there are posts asking for help solving things before the poster has really got stuck into it. Not everyone is a problem solver, and people take different things from lego, but for me, sitting and trying, re-trying, iteration after iteration, sometimes for days, is what i love... its like playing chess with lego pieces!
January 31, 20205 yr 1 hour ago, TeamThrifty said: Problem solving is a key part of technic.. quite often there are posts asking for help solving things before the poster has really got stuck into it. Not everyone is a problem solver, and people take different things from lego, but for me, sitting and trying, re-trying, iteration after iteration, sometimes for days, is what i love... its like playing chess with lego pieces! Agree, thats why I enjoy GBC with its complex gearing and trying to come up with workable solutions. My current build has gone through several solutions - workable but too slow so still under developement. Having said that can't se the point of super cars having 4 & 8 speed gear boxes if model is only for dis[play !
January 31, 20205 yr 1 minute ago, Doug72 said: Having said that can't se the point of super cars having 4 & 8 speed gear boxes if model is only for dis[play Agree completely.. mind you the whole display thing is lost on me, technic has mechanics at its heart, its meant to be used, taken to bits and re-used..!
January 31, 20205 yr 2 hours ago, TechnicBrickPower said: Hi Just an update...someone on reddit posted that you can create an exact 7:1 using a differential with 1:5, and 1:9 input to create a 1:7. Here is the comment on reddit. The mechanism was used to built a very interesting Antikythera Mechanism to calculate eclipses of the sun and the moon. Check the corresponding website, it's worth it! Edit: of course there is a dedicated topic on EB. Edited January 31, 20205 yr by Wismill
January 31, 20205 yr Interesting. It's not exact 1/7, as you show, but it's surprisingly close. In fact it's 20/12 * 8/24 * 8/24 * 40/24 * 8/24 * 20/12 * 20/24. This comes down to 5/3 * 1/3 * 1/3 * 5/3 * 1/3 * 5/3 * 5/6 i.e. (5*5*5*5) / (3*3*3*3*3*3*6) i.e. 625/4374 If you compare this to 1/7 by dividing it: (625/4374) / (1/7), then you get (625/4374) * 7 = 4375/4374. Interesting how these two highly-factorable numbers are only 1 apart. (sorry. Once a mathematician, always a mathematician :D ) How did you find these two numbers? By chance, or did you run some numbers beforehand to get it? Also, playing with gears is fun :D Edited January 31, 20205 yr by Erik Leppen
January 31, 20205 yr On 1/29/2020 at 3:22 AM, TechnicBrickPower said: Hi Everyone, I have made a video about creating a 7:1 gear ratio mechanism using just 2:1, 3:1 and 5:1 gears. No 28 teeth gears used. Youtube subscriptions appreciated! Kind Regards and keep building, Rob Hi, Please be aware that Eurobricks is not a platform to promote your channel. Thanks.
January 31, 20205 yr 1 hour ago, Erik Leppen said: sorry. Once a mathematician, always a mathematician Don't be sorry! I have just enough maths to do my job, but love to see some proper analysis!! Brilliant post.
January 31, 20205 yr 7 hours ago, Doug72 said: Having said that can't se the point of super cars having 4 & 8 speed gear boxes if model is only for dis[play ! For me one of the most interesting parts of designing a supercar is developing the gearbox. Then comes the different challenge of designing the car that looks good around it.
January 31, 20205 yr I agree, gearboxes are a fascinating thing to design and build... its just sitting them on a shelf as display-only that confuses me. I want to see them, and use them. Lego is about interaction. Airfix is about display... at least to me
February 2, 20205 yr Author On 2/1/2020 at 4:33 AM, Erik Leppen said: Interesting. It's not exact 1/7, as you show, but it's surprisingly close. In fact it's 20/12 * 8/24 * 8/24 * 40/24 * 8/24 * 20/12 * 20/24. This comes down to 5/3 * 1/3 * 1/3 * 5/3 * 1/3 * 5/3 * 5/6 i.e. (5*5*5*5) / (3*3*3*3*3*3*6) i.e. 625/4374 If you compare this to 1/7 by dividing it: (625/4374) / (1/7), then you get (625/4374) * 7 = 4375/4374. Interesting how these two highly-factorable numbers are only 1 apart. (sorry. Once a mathematician, always a mathematician :D ) How did you find these two numbers? By chance, or did you run some numbers beforehand to get it? Also, playing with gears is fun :D Yes you're right it's out by 1/625 from 7, i.e. 6.9984 = 7 - 1/625. I found this by running a search algorithm and it can find ratios to a high precision, but these need 1000's of gears - so not practical! For example 5 ^ 571 / (3 ^ 571 x 2 ^ 418) = 6.99999683.
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