DraikNova

A question regarding universal joints

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I am trying to figure out whether there's an easy way for me transfer motion between these two axles (yellow) that are at 120 degrees to one another (anchored in place relative to each other by the pieces in red). I have both terrible intuition and limited understanding when it comes to stuff like universal joints; can anyone tell me whether this setup of universal joints (with a horizontal bar formed by two of the yokes of the universal joints in the middle in blue) would reasonably work to transfer rotation so that if one of the axles was spun clockwise, the other would spin counterclockwise?

lego ldd universal joint question.png

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not sure i understand your intent. Both will rotate the same way. If you want to change direction, you'll need something like a gear pair or a twisted rubber band between two pulleys.

 

Also the angle is a bit too much for a universal joint. That setup will probably work if you're careful and gentle with it, but if you're expecting to put load on it or run it at high speed it probably won't reward you.

If it's hard to get your head around the movements, imagine it straightened out...

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I meant clockwise and counterclockwise as seen from the top (the plane in which the rotation of the axles takes place); although, of course, if this whole assembly was straightened out, that would amount to it all rotating the same way.

At any rate, do you have any advice on either a sturdier mechanism to use or a way to make this setup sturdier?

Edited by DraikNova

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41 minutes ago, DraikNova said:

I meant clockwise and counterclockwise as seen from the top (the plane in which the rotation of the axles takes place); although, of course, if this whole assembly was straightened out, that would amount to it all rotating the same way.

At any rate, do you have any advice on either a sturdier mechanism to use or a way to make this setup sturdier?

It depends of how much force they must transmit, this setup should work good with low torque and moderate speed, but once you start to increase any of these factors the problems come up, with too much torque this setup will surely wind up and jam, with too much speed the center section (blue) will have a lot of vibration because of the nature of the u-joints themselves, i am not sure if these angles are too sharp for the u-joints, but you could do a small test and if without any load you can see the setup starts to "jump" or jam then the angle must be decreased or you will need another setup.

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Ah. Thanks for the help.

I managed to find a solution that let me simplify the section I would have attached this to to the point that I can work without the weird angles that prompted me to try to use universal joints in the first place.

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I do think that is too much of angle for U-joints, except for the most rudimentary of motions. I think gears would be a better option, more specifically knob gears would probably be your best.bet. Or you could use two more U-joints and half the angle in doing so. 

Edited by Johnny1360

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Anything over 45 degrees is too much for Lego's current universal joints.

Edited by Zerobricks

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