What kind of shaft couplings are used in CNC?

 

Couplings are used to transmit torque even when the two shafts are misaligned. For CNC, it is used to connect the stepper motor shaft and lead screw / ball screw.

Rigid coupling:-

The default (and worst) coupling is a rigid coupling.

This coupling is good for transmitting torque between the two shafts, there is no backlash, but it does not allow for misalignment between the shafts and the shafts will soon wear out or damage.

 

Oldham Coupling :-

Oldham couplings have 3 discs (usually 2 metal discs and 1 plastic disc) and allow for parallel shaft misalignment (offset).

Oldham couplings may cut down on the game, but there are better options.

 

Jaw coupling:-

Known as Spider Coupling or Lovejoy Coupling:

The jaw coupling has two metal discs and an elastomer loading disc inside. Excellent for torque transmission and damping support, but with some clearance.

 

Helical coupling:-

What is known as a beam coupling is a hollow cylinder with a helical cut.

This coupling withstands some degree of misalignment and has low play.

 

Bellows coupling:-

Bellows coupling is a type of cylinder cut or electroplated to become a bellows.

This type of coupling allows for misalignment and the least play of "flexible couplings".