Thread: Hafco HM-46 z leadscrew problem

Hi all.

I've just bought a second hand HM-46 which has a fault with the z axis lead screw. The spur gear at the base of the column has popped out the alignment key and is dropping below the crank handle's spur gear.

Is anyone able to tell me the procedure for pulling the z lead screw? I want to confirm the keyway isn't damaged before attempting keyhole surgery and using the crank handle recess to replace the key.

I've attached a photo looking in through the crank handle recess. You can just make out the keyway above the spur gear.
Leadscrew.jpg

In case someone else has a similar problem, the issue was the tab washer at the bottom of the leadscrew. The inner locking tab had snapped off, allowing the 16mm nut to loosen and drop off.

Half hour of filing a replacement tab washer and it's working fine.