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Prusa i3 Aluminium - Z Axis threaded rods

Posted: Sun Feb 28, 2016 5:29 pm
by 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.
IMG_4800.jpg
With Z Supports
IMG_4800.jpg (28.45 KiB) Viewed 8383 times
I pulled the z supports off and ran the head up and down.
IMG_4802.jpg
Without Z Supports
IMG_4802.jpg (33.81 KiB) Viewed 8383 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 :(

Re: Prusa i3 Aluminium - Z Axis threaded rods

Posted: Mon Feb 29, 2016 11:09 pm
by 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?

Re: Prusa i3 Aluminium - Z Axis threaded rods

Posted: Mon Apr 25, 2016 6:17 pm
by 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.

Re: Prusa i3 Aluminium - Z Axis threaded rods

Posted: Wed Apr 27, 2016 4:00 am
by 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

Re: Prusa i3 Aluminium - Z Axis threaded rods

Posted: Wed Apr 27, 2016 4:23 pm
by 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

Re: Prusa i3 Aluminium - Z Axis threaded rods

Posted: Thu Apr 28, 2016 6:42 pm
by 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.

Re: Prusa i3 Aluminium - Z Axis threaded rods

Posted: Sat Apr 30, 2016 11:33 pm
by swittmann
IMG_5106.jpg
IMG_5106.jpg (37.58 KiB) Viewed 8075 times
Before and After

So much better. Thank you :)

Re: Prusa i3 Aluminium - Z Axis threaded rods

Posted: Fri May 13, 2016 3:42 pm
by archit3ct
Like a new printer.
Glad it helped you

Re: Prusa i3 Aluminium - Z Axis threaded rods

Posted: Sun May 15, 2016 9:30 pm
by 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

Re: Prusa i3 Aluminium - Z Axis threaded rods

Posted: Wed Oct 05, 2016 1:12 pm
by solder_guy
I'm in the process of build .. Would someone print these for me to save from building twice?

Thx

Rob