Name of this 'arm' on a stepper motor

Hi all.

Does anyone know what the name of this is?

The 'arm' that you attach to the shaft of a motor in order to turn things..?

i.e. this:

On a servo it’s called a horn. I don’t think I’ve ever seen one on a stepper.


Horn, crank.

On old disk drive head-drive steppers, the drive shaft stuck out both sides of the motor. On the inside was the split-band drive moving the head, and on the outside there used to be a crank (almost a paddle, really) like that, that went between a photo-interrupter to indicate track zero.

Very interesting, thanks guys. I think I will try to get some old floppy drives and pull them apart to see. Could be much cheaper than buying new.

You can also find stepper motors in old flat-bed scanners, to move the scan head along its track inside the scanner. Some kinds of inkjet printer also have stepper motors in them, for printhead and paper motion. As for disk drives, only very old (1980s) disk drives have useful steppers in them; modern drives have stepper motors that cannot be removed from the drive chassis as a separate item.

All the hard drives I've dismantled that were made in the last 10 years or so used voice-coil positioners. Which are useless for re-use, but contain very nice rare earth magnets.


We're thinking of floppy disk drives here. 5.25 inch ones, no less.

No, actually, I was thinking of some very old 5.25inch full-height Winchesters I had dismantled. A whole 20Mbyte capacity. :)

But yes, I haven't seen a HDD that didn't have voice coil actuators for quite some years now.