Zero backlash CV joint?

[beanbag]

Is there such a thing? I know that universal joints are not constant velocity. I need a small joint that can bend at least 30-40 degrees. I have some approx 1-2" diameter stock that I'd like to machine on the 4th axis CNC, but need the end mill to be angled relative to the rotation axis.

[saltmine]

Try an automotive swivel impact socket.

Not the chrome plated ones they sell at Sears, but a true, black oxide, impact socket. They use a ball & paddle joint similar to the old "knife & fork" joint VW used to use (on the Beetle)

A regular universal joint for 3/8" or 1/3" drive might work, except conventional style "U" joints don't like excessive angularity. It causes too much of a speed variation through it's rotation.

[The Artful Bodger]

You can make a form of CV joint that may be adequate for this task.

One shaft has a ball on the end and there is a pin through the ball at right angles to the shaft. The other shaft has a hollow barrel with an inner diameter to accommodate the ball and two slots to take the pins.

There is a similar type of joint, often with three pins, used on the inner end of the half shafts in many vehicles.

[topct]

Weed eater drive cable.

[small.planes]

How big? A lot of (modern) front wheel drive cars have fairly small CV joints, the (real) Mini has one thats about 2 1/2" in diameter IIRC, and is a 6 balls in a cage CV joint.

Dave

[pcarpenter]

If rotation can all be in one direction, I think I would approach the problem from the standpoint of pre-tensioning an available CV joint rather than from the perspective of trying to find one with zero backlash. I was astounded that I was able to buy the half-shafts, new, with both CV joints attached for my 4WD Silverado pickup for about $89. Because they were new, I didn't have to return my cores, so I kept one or both of them to use as "just in case" stuff someday....they would make a cheap PTO type shaft, or flexible drive from some small to medium engine etc. They are designed to turn quite fast (several times engine RPM) and are amazingly tough. In my case, it turned out that likely neither of the CV joints were bad. I had a bad wheel bearing and replacing the half shafts was a job more easily done while the hubs were apart.

In any case, a half shaft like this for some smallish front wheel drive car might suffice for your purposes.

Paul

[philbur]

Why does it need to be zero backlash.

What about a Bridgeport Quill Master type attachment.

Phil

Is there such a thing? I know that universal joints are not constant velocity. I need a small joint that can bend at least 30-40 degrees. I have some approx 1-2" diameter stock that I'd like to machine on the 4th axis CNC, but need the end mill to be angled relative to the rotation axis.

[Arcane]

These aren't CV joints, but they have quite a selection of very small sized universal joints if you end up going in that direction instead.

[DICKEYBIRD]

They are designed to turn quite fast (several times engine RPM)....

Don't half-shafts turn at wheel speed? Just sayin'...

[Richard-TX]

Don't half-shafts turn at wheel speed? Just sayin'...

yes, and if you connect 4 of them together it goes at 2 x speed.