Split coupling 1

[eaglet]

I am designing a brass split coupling to be used in a four jaw chuck to prevent damage to a shaft from the jaws while the shaft is being turned. The OD of the shaft is 2.5590 +/- 0.0001. If I am going to make the split in the coupling 0.125, will it be okay if I make the ID of the coupling 2.565 or should I make it slightly larger?

 

[rhodie]

Considering the amount of clamping pressure that is going to have to be applied to the coupling to keep the shaft from moving during the machining operation, I would say that the maximum ID for the coupling should be 2.5589".

I am assuming that the split coupling you are talking about is two-piece. That, and I am assuming that you need a slight interference fit on the shaft as to eliminate any chatter or movement during the machining operaton.

Your tolerance = 2.5590 +/- .0001
Maximum Mat'l Condition of shaft = 2.5591
Minimum Mat'l Condition of shaft = 2.5589

You must accomodate the minimum mat'l condition in order for your coupling to be useful in all situations.

 

[EnglishMuffin]

I've done this a number of times - you don't have to make it two piece - just use one slit, its easier to handle. If it has a relatively thin wall, say 1/4", you can get away with two or three thousanths clearance - it will close up OK.

 

[desertfox]

Hi eaglet

When I had a situation such as yours where a part had to be
protected from damage, I used to remove the standard jaws
and replace them with soft mild steel blank ones,which after
centralising were bored out to the component size.


regards desertfox

 

[eaglet]

Thanks to everyone for their input. I am going to use a coupling with a single split on one side. I am also looking into purchasing some smooth, mild steel chuck jaws.