Where to buy a 'Robot sized' CV Joint

[steadfasttuna]

I have been looking for a CV joint to use on our robot. I cant seem to find one online that is small enough to use on our robot.


Thanks,
Hamzah

[MrForbes]

There is a simple type used on some radio control cars, that is sort of like a "dog bone".



The end fits into a socket that just has a hole drilled in it, and a slot cut across it.

You might be able to make this if you have a lathe and drill press.

[Justin Stiltner]

Not CV joints, but this may work for ya
http://www.sdp-si.com/web/html/univjoints.htm

[ggoldman]

You do not need to use an expensive CV joint.

You can just use two simple Universal Joints in Series (each bent at the same angle) to create a CV joint.

This is called a DOUBLE CARDIAN joint.

If you do not use two, it will not be a constant output velocity.

Hope this helps!

[SWIM]

Another related issue...

Where can you buy a robot sized differential? Preferably limited slip or locking...

[Dick Linn]

Hey, Gabe, how you doing?

Funny thing about some of those joints, about the velocity and so forth. Tricky stuff it can be - not always apparent.

You doing OK? Congrats on the climbing "noodle" 'bot there.

[Devo1098]

CVD's and differentials?

sounds like a 4wd Ackerman steering bot to me....

with the low traction you really don't need either. just let one slip, i even like how a solid axle handles (rc car racer)

instead of cvd's i thought of using a flex shaft, honestly, with the almost no traction your not gonna be able to put down any power, so in this situation, you could get away with it.

you can call me a idiot for cheating the differentials and constant velocity shafts, but your not trying to make it last thousands of miles before a tire change, and the low friction even helps this fact.

[ggoldman]

Originally Posted by Dick Linn

Hey, Gabe, how you doing?

Funny thing about some of those joints, about the velocity and so forth. Tricky stuff it can be - not always apparent.

You doing OK? Congrats on the climbing "noodle" 'bot there.

My research focuses a lot on the properties of universal joints, so I know all about how they work (even the non-apparent properties)



I am doing fairly well, and the press on my robot has been crazy...have an interview with Popular Mechanics today, we will be in Pop. Sci and Inc magazine soon. Been keeping my hands full working with team 401.

How have you been doing? (Might be best to send me a PM back)

Best,

-Gabe

[IKE]

Originally Posted by steadfasttuna

I have been looking for a CV joint to use on our robot. I cant seem to find one online that is small enough to use on our robot.


Thanks,
Hamzah

Can you describe the application a bit more? Something as simple as a bellows joint or spider coupling may be sufficient. Torque? Application?

[steadfasttuna]

We are trying to steer powered wheels and we need the shaft to be able to have a bend in it and still transfer power. I first was looking for a U joint but one of our mentors said that it would not give us a constant power, in other words it would be 'jerky'.

[IKE]

Originally Posted by steadfasttuna

We are trying to steer powered wheels and we need the shaft to be able to have a bend in it and still transfer power. I first was looking for a U joint but one of our mentors said that it would not give us a constant power, in other words it would be 'jerky'.

For this year, you could probably get by with RC Monster Truck 4x4 front end units. Any good RC place should have the right stuff.

Typically for FRC robots teams build steerable pods (see swerve drive, or crab drive threads).

Teams with (in my opinion) excellent crab drive modules to benchmark would be 111, 496, 71... And many others. With the low torque and low skid traction this year, it might be a good year to try making a Crab drive module as typical failure modes should be less due to the lower loads.