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.
@Pete Chiewhawan Remove the lead screw then adjust the gantry guides. It's futile trying to feel for the alignment when the only way to move it is by turning the lead screw.
You can easily remove the lead screw by first removing the motor coupling and support bracket. Be sure to support the gantry as you do this. With the coupling and bracket out of the way, gently let the gantry wind all the way down. Then you'll be able to lift the lead screw straight up until it is blocked by the upright bracket. Gently move the gantry up as high it will go and the lead screw will slip right out.
As you adjust the gantry guides, make it slide best in the lower third. For me, that meant leaving an uncomfortable amount of wobble in the upper half. But, at least I was able to print Benchy ... and some other short parts. It might get you printing. But, I can't say whether it's a solution since I don't know how it will affect printing in the upper z bounds.
edit: Oh, and you can reinstall the lead screw by simply following the above steps in reverse order.
edit: Btw, this is exactly what I was talking about my thread: https://www.forum.makertech3d.com/forum/assembly-1/wobbly-platform-and-sticky-z-motion ... as I see more people having the same issue the more I think there may be something to the angle of the metal folds ("rails") that the gantry, print head, and platform slide on.
The gantry getting slightly stuck on the way down is normal and then solved by the bracket at the top of the lead screw. It should push down on the lead screw in order to prevent the coupling from stretching.
Make sure however that the top of the silicone cap is lubricated and not sticking on the bracket.
Hey @Pete Chiewhawan , you should check out this: https://www.forum.makertech3d.com/forum/3d-printing/improving-print-quality