Guys, i see some artifacts on my prints that are related to my z axis threaded rod being crap. I have some ss m5 rods and some bronze nuts, im thinking on installing them and see if it’s better. Any suggestions?, being ss vs bronze, i guess i should maintain the nuts well oiled (that sounded a bit weird).
What is currently installed?
Make sure the rods are not constrained on the free end. I understand a piece vinyl tubing secured with zip ties makes a good coupling for M5 rod to the Ø5 shaft on the stepper.
Right now its regular threaded rod with regular nuts, the kind you can get cheap at any hardware store.
The ends are free (its a prusa i3) and im using alu couplers.
thanks!
Are you getting wobble (helically misaligned layers) or banding (some layers wider than others)?
banding
That suggests to me that your layer heights may not be matched to full step positions on your Z axis motors. Here’s a handy calculator: http://calculator.josefprusa.cz/
Done that, im using the correct steps and correct layer height.
OK, had to put it out there. I’m not confident that changing threaded rods and nuts is going to have an impact. I think I would next look at temperature stability of the hot end and maybe the heated bed. PID calibration, thermal mass, length of melt zone, etc.
I compared a standard threaded rod from Ace to a similar ACME leadscrew from McMaster, The difference is night and day. Just saying from practical experience 
When I checked the regular threaded rod for every rotation the actual change in height was measurably different from thread to thread. On the ACME leadscrew each rotation produced exactly the same movement of the nut.
I think that leadscrews are the way to go