[Started to get some random, yet extreme, Z artifacts on one of my UM2's]

So if I understand this, you swapped the z motor and nut and all is well now?

I am still having the issue on mine, sadly the machine just sits these past months, printing only flat items, like tokens for makerfaire and such.

I'd try replacing bowden tube. I can now print at 15mm^3/s with this.

[US buyers I found a good & cheap bowden tube replacement]

I was getting massive underextrusions from a bowden tube purchased from gr5 store.

And I found this:

Fluorotherm F015092 - 5 Fractional PTFE Tubing, 1/8" ID x 1/4" OD, 5' Length, Semi-Transparent

It's long enough to make two and works like a charm. The OD fits the white clips perfectly, and I am able to use 3mm (as opposed to 2.85mm) filaments as well.

The only downside is that it's much less transparent, making light-colored filaments hard to see through.

[Started to get some random, yet extreme, Z artifacts on one of my UM2's]

@gr5

You were right on - everything is in perfect working order!

Thank you always gr5 for your quick responses.

[US buyers, try Atomic Filament]

I've been looking for cheaper filaments for my UM2. Being used to top-of-the-line stuff like Ultimaker, Faberdashery and Colorfabb, it was difficult to find any decent replacement. eSun was especially a huge nightmare, despite its low cost.

I tested out Atomic Filament recently, and it's been giving me decent prints.

It's $29.99 for 1KG spool with free shipping. Definitely worth a shot.

http://atomicfilament.com

[Started to get some random, yet extreme, Z artifacts on one of my UM2's]

@gr5

Just got an email from US Support-

They are sending me a new Z-motor and trap nut!

I will let you know how it goes

[Started to get some random, yet extreme, Z artifacts on one of my UM2's]

@cloakfiend

The extreme lighting and the glossy nature of that PLA is making it look melty. It's not melty at all actually. In fact, the strata is quite sharp. I am sure the temperature is not an issue. I am very familiar with the consistency vs temperature since I've been printing daily for about a year. The temps are correct for sure.

I do like your idea of swapping out PTFE and the Olsson block. I will give that a shot some time.

@gr5

I've been contacting the US support, but it has not been terribly productive so far. I have even taken the entire Z assembly (brass nut, screw and motor) out and meticulously cleaned it and regreased it with Magnalube. Nothing changes!

[Started to get some random, yet extreme, Z artifacts on one of my UM2's]

@gr5

@cloakfiend

I made a 3D model for the test. It's 10 x 10 x 10 mm box with 5mm tall extruded curve sitting gently on top.

* My nozzle is thoroughly cleaned out, and can achieve 10 mm^3/s

* All filaments I own gives same result.

Here are the parameters:

 

Material: Colorfabb PLA/PHA Gray

Shell: 0.8 mm

Bottom/Top: 0.8 mm

Fill: 30%

Speed: 50 mm/s

Infill speed: 80 mm/s

Top/bottom speed: 15 mm/s

Outer shell speed: 30 mm/s

Inner shell speed: 60 mm/s

 

 

Here are the results

 

 

Larger layer height seems to make problem worse:

Z current doesn't seem to have any effect: (It sounds a little quieter. I like that.)

Lowering temp down to 205 did not change anything:

[Started to get some random, yet extreme, Z artifacts on one of my UM2's]

Thank you guys for helping out!

- Here is my .ini file

- My layer height was 0.1mm for the "horizontal banding test towers" and 0.2mm for the rest.

- I've tested with temperatures ranging from 200 to 250, with Ultimaker PLA, Colorfabb PLA/PHA and Faberdashery PLA. All combination leads to the same result.

@neotko I even took out the brass nut and the threaded rod assembly and cleaned and re-greased it thoroughly. All three Z thumb screws are on tighter side to reduce vibration. I don't think it's bed leveling issue either.

@gr5 I am using the Olsson block that I got from gr5 store. I was printing fine with the Olsson block for the past month. I took apart and reassembled the head assembly just in case, but nothing changed.

I will try printing 10mm tall object and measure with my caliper. I will also try adjusting Z current.

@cloakfiend I cleaned out the nozzle thoroughly and I am easily getting 10 mm^3/s flow. I will check the nozzle for any slight blockage and try printing cooler.

Thank you all, and I will post some test results later.

[Started to get some random, yet extreme, Z artifacts on one of my UM2's]

I am having the exact same problem!

I can rule out temperature/speed, filament, slicing or firmware issue. I highly suspect that the problem resides within the Z axis (Z threaded rod, Z motor or Z driver).

- It happened randomly. I was printing fine, then my UM2 started to print like this.

- I removed the threaded rod from the machine, cleaned with WD-40 and re-greased with supplied grease. The two sliding pillars are oiled properly.

- There is no resistance or bump when I manually move the bed up and down.

- All belts are nicely tensioned.

- Printer works perfectly except for the Z banding issue.

Any updates?

[US Almost a week since payment. Shipment is "READY"]

UPS left notification and left (signature required) since no one was home. So I ran to the UPS truck from school and got my package straight from the truck.

 

Unpacked, loaded PLA, and and sent a 30 hour print.

 

 

[US Almost a week since payment. Shipment is "READY"]

Great! Tracking says the item is picked up (TN) and it will be here (NY) in 2 business days (UPS Ground).

 

[US Almost a week since payment. Shipment is "READY"]

I placed a US order for UM2 on Sep 26, but the order status is still "Ready". I paid in full at the time of purchase.

What's stopping from the US vender to ship the item quickly? Are they assembling as they go?