[SScnc]

My Z stepper has started missing steps when going up and then it actually hums and reverses !

It reverses in a "slow motion" manner while the motor hums. I put my arm on the head of the X2 while jogging up and it does it every time. I do have to put pressure on it though. I completely loosened the gibs and it made no difference.

I then switched cables with the Y and the Z behaved the exact same so it's not a particular driver. I'm using Keling 4030's and 36v PS.

I really need some help with this, I'm trying to mill the second half of a mold and have already ruined one block of aluminum because the Z didn't lift up.

Any ideas on what is causing this ?

Thanks,

Steve