Fix for inconsistent layer height?

[mechamecha 64]

Lately I've been having trouble with excessive horizontal banding on my prints. I don't often use transparent filaments, but today I did and discovered that I'm definitely getting inconsistent layer heights in my prints. I even watched and could clearly see a slightly larger distance between the print and nozzle on certain layers.

How do I go about fixing this? New Z bearings?

Edited January 26, 2017 by Guest

[neotko 1,417]

Try on this order (from cheaper to more expensive)

- Clean z screw with a toothbrush with lube on it.

- Apply a drop of oil on the z shafts (according to Sandervg it can be done) 'but not on the z screw'

- Buy good quality z bearings and replace the stock ones.

Or alternatively you can do this mod by @Gudo buying one z nut and a spring:

http://www.3dprintingforum.us/viewtopic.php?f=12&t=549#p8035

I will record a easy/fast tutorial of how to do it this weekend. Imo is the cheapest solution, but also really good quality z bearings will only help.

Edited January 26, 2017 by Guest

[mechamecha 64]

Thank you very much for your helpful reply, neotko! I'll give your suggestions a try. Are these the right z bearings for the Ultimaker 2?

The link you provided gives me this message: "The requested topic does not exist."

[neotko 1,417]

Fixed link

[neotko 1,417]

Indeed that's one of the best linear bearings you can get. Also misumi sells a C- (cost effective) version that works quite nicely too.

https://ultimaker.com/en/community/18394-sounds-like-theres-sand-on-the-z-screw?page=last#reply-135065

Fbr8 did sent that ones to an user that had problems with the z

If your printer is under warranty you could try that path too.

[mechamecha 64]

Nope, my printer is several years old.

Thanks again, neotko! I'm looking forward to your tutorial.

[mechamecha 64]

I'm posting a follow-up in case anyone else has been experiencing this crazy problem. So I ended up ordering some new z-bushings from Misumi and installing them on my Ultimaker 2, and guess what? The problem was still there!! Same inconsistent layer heights! At that point I was thinking, "What the heck! I guess I'm going to have to replace the entire z motor assembly?!"

After blowing off some steam, I decided to change the firmware on my printer, just for the heck of it. A month or so back I had Cura 2.3.1 install the latest "official" firmware on my machine because I was having some issues with the Tinker firmware like weird air printing in random places. So I reinstalled the latest Tinker firmware, and what do you know! Problem solved!

Then the Tinker firmware was giving me ERROR - STOPPED messages and ruining my prints, so I went back to the official firmware. At first I thought the problem hadn't returned because I was printing with .06 mm layers for a while, but when I started printing at .2 mm, I immediately noticed the inconsistent layers again. So now I'm back to Tinker firmware 16.03.1, which is the last problem-free version I remember using. Again, problem solved.

[mechamecha 64]

The only difference between the two prints below is the firmware. The print with the odd stripes was done with the official Ultimaker firmware, the other was printed after installing Tinker firmware 16.03.1. Obviously, there's some kind of bug in the official firmware.

[neotko 1,417]

That reminds me of this

https://ultimaker.com/en/community/17720-z-banding-when-ever-i-use-infill-whats-wrong

Maybe the issue comes with temperature fluctuations on the heater?

[mechamecha 64]

Thanks for replying, neotko.

As I mentioned before, the only difference between those two prints is the firmware. All print settings – speed, temp, layer height, etc. are exactly the same. I printed the striped one with the official Ultimaker firmware, then immediately installed the Tinker firmware and printed the other one, which looks fine. I encountered the exact same results the last time I switched between the two firmware versions.

Would each firmware install different PID settings?

Edited February 15, 2017 by Guest

[neotko 1,417]

The only difference I can think of is that maybe @tinkergnome knows, do tinkergnome firmware changes PID bed from bangbang to PID ? Because PID on Bed is much more reliable and stable.

Or maybe the default firmware is pushing too much power to the hotend making it harder for the PID to be accurate?

I would change to old firmware and check the temp on the hotend, I only can think of a 5C variation while printing to make a constant mark like that.

But also, hey if works...

[tinkergnome 926]

Would each firmware install different PID settings?

 

The standard firmware does not use PID at all for the heated bed. So there is a difference - yes.

There were longer discussions in the past (at the time the PID mode was changed for the standard firmware). If you're interested:

firmware surface kwality bug 14.07 vs 14.03

Horizontal banding on UM2

[mechamecha 64]

Thanks for replying, tinkergnome, and thanks for all the work you put into your firmware mods!

I guess that's what the problem is, then: PID mode vs. bang-bang mode for the heated bed, although it's strange that a setting for the heated bed would cause major fluctuations in the hot end temperature.