I'm struggling to get the "tight grip" on the pillar rails that its tight enough to not have a wobble but loose enough for the gantry to move up and down freely when turning the lead screw by hand (stage 6, step 11). It would move up fine but moving it down, it would get stuck for half a turn before the coupler brings in down.
I've tried the following with no avails:
-lubricant
-checked that my lead screw is straight
-tried using the stepper motor to drive with but still can't get it to come down smoothly
Been adjusting it for 3 days now. I was also one of those with the extra eccentric guide instead of the fixed one, thought that might have been the issue and printed a fixed guide from an SLS printer but that still didn't solve the issue.
@andrew leroy @Michael G Thank you both for your help! I tried following your instruction but didn't manage to get take the lead screw out without completely removing the eccentric guides.
HOWEVER! I managed to get it working smoothly through the whole Z-Axis length! Could just be luck but I did following:
1) Slightly loosen the 3 screws holding the lead screw nut. Only by a tiny amount to allow for the smallest amount of wiggle
2) Reverted back to an three eccentric guides and one fixed guide on the gantry to allow for a better adjustment
3) Use a lot of lube on the rubber cap at the top of the lead screw
4) Lower the gantry down until the print head touches the bed (I had the hot end rubber sock on just it case)
5) Adjust the 3 eccentric guides until there's only a slight wobble, and the gantry will slightly gets stuck when lowering but easily falls down when wiggle the far end of the gantry.
6) Stop the lead screw from moving whilst push down lead screw top bracket in place. This should stop the stutter as suggested by @Makertech 's comment
7) Did further adjustments on the eccentric guides until I was happy with the lack wobble and smooth motion
I did notice that lowering the gantry down by hand could sometimes cause the top of the lead screw to slip from the top bracket but this didn't happen when I used the pronterface to move the gantry down. I might redesign the top bracket to add a lip to stop the lead screw from completely slipping out.