Prusa i3 Aluminium - Z Axis threaded rods

[swittmann]

I'll start by saying this is my first 3d printer, and this is the first time I'm posting here.
I have a Geeetech Prusa i3 Aluminium.

I'm getting quite decent print quality + some terrible z banding.

With Z Supports

IMG_4800.jpg (28.45 KiB) Viewed 20196 times

I pulled the z supports off and ran the head up and down.

Without Z Supports

IMG_4802.jpg (33.81 KiB) Viewed 20196 times

One of my threaded rods seems to move in large circles at the top where the other moves in a small circle.
The brass bush on the "wobbly" side is quite tight where the side that doesn't move around a lot can actually be wobbled in the bush itself.
I did a print of a calibration cube with no Z supports and it came out much better than with the Z supports on.

Has anyone created a part that does not hold the threaded bars in place for this printer?
Is there anything else that you would recommend to try and resolve this issue?

I found one on thingiverse for geeetech prusa i3 but it didn't fit this printer

[Mark]

check your rods are bended or not, and the couplings on the Z axis, are the two holes of it line up with each other? how's the coaxiality?

[archit3ct]

Print these 2 brackets and remove the brass nut.
http://www.thingiverse.com/thing:1431036
They do a fantastic job.. The wobble is not transferred to the print.

[mark2]

That looks like an excellent solution to the wobble problem!

How does the piece stay on the threaded rod? is it threaded itself? or does it have a captive nut?

I can't tell from the pictures

[archit3ct]

Check this item also. Same thing. More clear pictures and video
http://www.thingiverse.com/thing:1424358
I printed two myself and they are amazing.
X axis is free from the Z screws so its only moving on the rods

[swittmann]

Much appreciated!
I purchased some new threaded rod which made very little difference.
I've printed out a couple of these but have not installed them just yet.
I'll install them over the weekend and see how it goes.

[swittmann]

IMG_5106.jpg (37.58 KiB) Viewed 19888 times

Before and After

So much better. Thank you

[archit3ct]

Like a new printer.
Glad it helped you

[mark2]

Printed too myself, but not yet fitted.

My Z-wobble is less severe than yours swiftmann, because I have already done some mods - I printed some different couplers and suspended the threaded rods using race bearings at the top - but it is still there, and I still get squeaking, so will update the thread when I finally fit them

[solder_guy]

I'm in the process of build .. Would someone print these for me to save from building twice?

Thx

Rob