I have been thinking about making functional mini-models with technic, but even 3L u-joints are too long for very small models, so I wanted one in 2L. This is my crude prototype for a 2L universal joint:

To attach normally through technic liftarms and bricks, it would also need axles in 2.5L, 3.5L, etc., and a 1L axle for attaching them back to back.

It would not be for heavy-duty models because of its weaker 1/2 stud connection, but I think it might be a good idea for low-torque applications.

Please feel free to add your opinions and criticism!

Welcome to Eurobricks!

I like your ideal, there are many applications that require short u joints, could you give us some test results?

The connection of 0.5L would just not be strong enough imo

I say cut of the rest of the axle holes and instead attach 3 long axles to each end of the joint. This way the twisting part would be 1 long and much easier to use.

(might be tricky to shape by yourself)

@skppo What do you mean cut the rest of the axle holes? I'm not sure I get what you're saying.

Welcome to Eurobricks!

I like your ideal, there are many applications that require short u joints, could you give us some test results?

How would I go about testing it?

Edit: Never mind I get what you're saying skppo but it would also need to come with 2L for maximum compatibility because when it goes through a technic brick or liftarm, with the 2L there would be a 1-stud connection and with 3L there would be a 2-stud connection, and past that you could just use axle joiners. Good idea though!

The connection of 0.5L would just not be strong enough imo

Yeah I get it but I said for small models that are around this size: http://laix-engineer...nimog-u400.html

Edit: Sorry, I just meant to say stuff with manual functions.

Edited May 4, 201311 yr by TwentyLeggedHen

I like the idea but id make a uv joint with a 4L axle on one side and a 1L axle on the other

This way you can un clip the sides and have two 4L or two 1L or have one side with a regular uv joint from the 3 or 4 lengh versions.

So with the 1 and 4 L axles you can have them closer to the wheel and parralel with where the pivot for the hub and wishbones are.

The uv joint has these axles as part of the brick)

Lego make a part that is kind of compatible with the UV joint inner core, you just need two of them, however they unclip easily since there slightly wider than the pins on the core of the uv joint.

It is the green bit of this assembly

http://www.bricklink.com/catalogItem.asp?P=30488c01

Edited May 4, 201311 yr by SNIPE

How would I go about testing it?

Making small cars and running them under different weights.

I like the idea but id make a uv joint with a 4L axle on one side and a 1L axle on the other

This way you can un clip the sides and have two 4L or two 1L or have one side with a regular uv joint from the 3 or 4 lengh versions.

So with the 1 and 4 L axles you can have them closer to the wheel and parralel with where the pivot for the hub and wishbones are.

The uv joint has these axles as part of the brick)

Lego make a part that is kind of compatible with the UV joint inner core, you just need two of them, however they unclip easily since there slightly wider than the pins on the core of the uv joint.

It is the green bit of this assembly

http://www.bricklink....asp?P=30488c01

I was thinking the same kind of thing, but kind of like a u-joint axle. It would be like this part: http://www.bricklink...tem.asp?P=87083, with something like this on it: http://www.bricklink...tem.asp?P=2609b that would fit this: http://www.bricklink...tem.asp?P=62519.

Also, those soccer pieces are so incredbly cheap! You can get 4 of them for absolutely free here: http://www.bricklink...itemID=29690861

Edit: The u-joint axles would need a part similar to the universal joint centre, but smaller.

Edited May 5, 201311 yr by TwentyLeggedHen

Oh and also, for 'u-joint axles', there would have to be a double centre piece like in this to save even more space: http://commons.wikim..._(animated).gif

Then again, when I think about it, there would also have to be different length centers...

Edited May 4, 201311 yr by TwentyLeggedHen

If you just cut off the part where an axle goes in, and put axles of some sort coming out that are permanently attached, then the joit itself would only take up one stud of space.

If you just cut off the part where an axle goes in, and put axles of some sort coming out that are permanently attached, then the joit itself would only take up one stud of space.

Geez thanks, that's what I just said.

The connection of 0.5L would just not be strong enough imo

That is true for the connection but as long as the axle does not slip out of the U-joint it could work. I'm am forced to use 1/2 stud axle connection on some of my vacuum engine because of the fake engine crank parts. I've had the crank split apart in the middle of a run because of a loose (none tight) axle connections with in the crank piece.

If you just cut off the part where an axle goes in, and put axles of some sort coming out that are permanently attached, then the joit itself would only take up one stud of space.

Sounds like some Jb weld is needed here.

That is true for the connection but as long as the axle does not slip out of the U-joint it could work. I'm am forced to use 1/2 stud axle connection on some of my vacuum engine because of the fake engine crank parts. I've had the crank split apart in the middle of a run because of a loose (none tight) axle connections with in the crank piece.

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Sounds like some Jb weld is needed here.

Where do you get Jb weld?

I think some kind of glue might work anyway.

Edited May 5, 201311 yr by TwentyLeggedHen

@ TwentyLeggedHen: JB Weld epoxy is found at Lowe's, Home Depot, and many other hardware stores in the USA:

Making small cars and running them under different weights.

I'm not sure what kind of car I should test it with. Could you tell me or show me a picture?

I was thinking of even making a small car out of sheepo's modular platform thing. http://www.eurobricks.com/forum/index.php?showtopic=66152 ( I just wouldn't add the out side body. ) Then you could put different weights on them. (0.5 lb, 1lb, etc..) After that you could see when they break and that could be around the torque limit.

I was thinking of even making a small car out of sheepo's modular platform thing. http://www.eurobrick...showtopic=66152 ( I just wouldn't add the out side body. ) Then you could put different weights on them. (0.5 lb, 1lb, etc..) After that you could see when they break and that could be around the torque limit.

OK I will do that sometime but I'm waiting for my BL order for the 6.5L steering links and the cv joint hubs(with 4 ball joints), and I will also have to sort my liftarms because I don't really have any at my disposal right now.

Edit: Should I just put the 2l u-joints where the 3L ones should go? Also I'm not sure if they will fall off and/or break before the cv joints do.

Edited May 5, 201311 yr by TwentyLeggedHen

I can't wait for the results then Hopefully you don't break too many u joint. You could also change different motors in your test too, to see what motors you should use and not use.

@ TwentyLeggedHen: JB Weld epoxy is found at Lowe's, Home Depot, and many other hardware stores in the USA:

Thanks DLuders! I am going to get some today, sounds pretty useful.

But you also have to be careful with the JB wield, make sure you don't mix it with magnets!

I can't wait for the results then Hopefully you don't break too many u joint. You could also change different motors in your test too, to see what motors you should use and not use.

Ok but it might be awhile, I will get to sorting and building right now, but MPS is pretty big, and I don't have LDD, so I will get that too.

But you also have to be careful with the JB wield, make sure you don't mix it with magnets!

What happens to JB weld when you get it close to magnets?

Whoa... I did not see that coming. I guess I better be careful, I have these magnets called buckyballs and they are just kind of lying around, so I better watch out.

Where do you get Jb weld?

I think some kind of glue might work anyway.

Lego is made from ABS; wouldn't ABS plumbing glue work? Just a thought...

Lego is made from ABS; wouldn't ABS plumbing glue work? Just a thought...

Yes, solid as a rock with only a very small application and dried clear. Note plumbing glue has extremely strong vapor trails. Don't glue indoors near furnace.... just a thought.