Z Banding wont vanish

[Schoffra 1]

Hi folks. I am despretly looking for a solution with my S5. I always had Z-banding and thought it has something to do with under extrusion as underextrusion was a problem with other parts too. So I installed 2 bondtech extruders. So far they work very well and it seams that the material flow is much mor constant than before. But now the Z-banding got much clearer then before. It seams that the problem occures very regularly as the bands have more or less the same distance to each other. Any suggestions are welcome. 

 

Things I did so far: 

- Belts tightned

- Z-Rod cleaned

- new extruders

 

The Model was printed with:

- Polymaker Terra PLA at 210°

- 75 mm/s 

- 0.2 mm Layer hight

- The walls are very thin (3mm) so there is no infill. -> Can this be the problem? 3 mm / .4 mm = 7.5? As the walls are not a multitude of 0.4 mm there is to much material within 1 layer?

[Slashee_the_Cow 271]

46 minutes ago, Schoffra said:

Can this be the problem? 3 mm / .4 mm = 7.5? As the walls are not a multitude of 0.4 mm there is to much material within 1 layer?

No. Where there's a discrepancy like that Cura will round it to (IIRC) the nearest multiple of either Quality > Wall Line Width or Quality > Wall Line Width ± Walls > Minimum Wall Line Width, depending on which is closer... or something like that. Either way, the important part is that it rounds it to something it can do.

 

If you could share a Cura project file like your example there (.3mf, in Cura get it ready to print then go to File > Save Project) that would help because then we could see all your settings.

 

Off the top of my head, about all I can think of right now is make sure you have Cooling > Fan Speed set to 100%, but given PLA is fairly temperature stable, I don't think that would be a fix.

[gr5 2,176]

Whenever I see that pattern it's almost always related to the zscrew.

 

Did it do this from the beginning?  Or did this gradually happen over many months/years?

 

I know you said you cleaned the z screw but sometimes you need to take it out. I believe it's attached to the stepper so it all comes out (not as hard to do as you might think but you have to get to the 4 screws that hold the stepper), put it on newspaper, spray with wd-40, clean with toothbrush, dry it off, put a pea sized drop of grease on it and then put it back together.

 

When you cleaned the z screw did you use a toothpick or something that gets into the cracks?  Did you realize it's a triple helix and you have to get all 3 threads?

 

If you measure the distance of 3 threads on the z screw (one rotation) is that similar to the height that the pattern sort-of repeats?  If so then on thread is dirtier than the other two.  Maybe.

 

The issue can be with the nut as well but in my experience, cleaning the z-screw very well is usually enough.

 

As a test you can just clean the 4cm of z-screw near the top that is used for prints shorter than 4cm in situ (without removing). You can use a paper towel and a very small screwdriver and a friend to spin the z screw. Or put rags around/under the area and use a toothbrush and wd-40 (and paper towels or rags to dry).

[Schoffra 1]

Thank you 2 for your replies. 

1. I will post the project file as soon as I am at home 

 

2. - I bought the printer in a used state and i think it did it from the start. I own it for like 3 weeks now. 

- I did not remove the screw to clean it. I used a tooth brush and isopropanol until there was more or less no more residue visible. maybe there are some junks in the threads left. I will dismount the whole thing and clean it with wd 40 as you suggested. 

- The distance between the line on the surface of the print is about 4.5 mm sometimes its a bit more but overall its like that. 

- Can I dismount the nut and check for that on the S5? 

 

I will report back as soon as I checked all of the points. 

 

Thank you 2 a lot

[gr5 2,176]

I've never removed the nut on the S5 but I know it comes off pretty easily on older models and in general, Ultimaker printers are pretty easy to take apart and put back together.

 

The threads appear to be about 2mm so with triple helix, one rotation would be 6mm.

 

If you remove the Z screw then you can slide the bed up and down to see if there is some strange friction related to the two vertical rods and their bearings.  Maybe those bearings need to be cleaned?  They are linear bearings with balls inside.  You shouldn't need any lubrication but some people do lubricate which can attract dust and the dust can get in the bearings.

 

Another interesting test is to put a brick or similar weight at the back of the printer (after it starts printing).  If this improves things then there is some kind of dirt/friction causing problems in the z screw or z rods.

[Schoffra 1]

Hello guys. I just cleaned the rod and the nut. The rod was already very clean as I cleaned it before. Bot now it is shiny as new. In the nut there were some plastic junks and very thik greas. I cleaned the nut with WD40 and a small round brush. Now also the nut is shiny. A testprint is on the way. 

the project file is attached.

 

UMS5_Gehäuse mk2.3mf

[Schoffra 1]

hello guys. I wanted to give you an update on my case. sadly the z lines are still there.

- I tried different PLA, on yellow it seems to be better but that could only be due to the color and the contrast. 

- i used simplify 3d to eliminate a slicer issue. still there on the same hights. 

 

I think that there is a little problem with the Z-bearing. I dont feel any segnificant resistance but maybe on the mm scale there is. So I ordered two new bearings (wtf how much they cost xD) 

 

I will keep you up to date as soon as I swapped them. 

 

 

[gr5 2,176]

How much did they cost?  I seem to remember someone bought the "more expensive" version and it was $3?

 

[Schoffra 1]

a bit more. I found 2 on amazon for 90 CHF. 

https://www.igo3d.com/ultimaker-s5-linearbearing-bed/

[Schoffra 1]

hello guys. I wanted to give you an update on my testing. After intense cleaning the lines were getting worse (model on the left 1st picture). because of the pattern the lines had, I sugested some issues mwith the bearings or the nut. So I wanted to eliminate the nut as potential problem and removed it for cleaning. it was pretty clean from the last cleaning. but I realized, that the cover at the back of the bed was giving some friction to the guidingbars. So I removed the cover. then my printer came up with something new. as you can see in the right picture, the line problem is much less. but in the first cm there is a new linepattern which vanished after short. IT seams as if it disapeared as soon an the gap started in the model. any suggestions what that could be? this thing drives me crazy!

 

Edited April 18 by Schoffra

[Schoffra 1]

does anyone of you know what pitch the z screw on an s5 has? 

[Schoffra 1]

Here are the latest updates on this case. yesterday I replaced the Z-Nut and did a testprint. Sadly this did not solve the problem. Strange thing is, the lines are getting clearer and clearer after each attempt of making the Z-Movement smoother. they are now +- 4.3 mm appart from each other. 

The new linear Z bearings arrived also yesterday. So this will be the next step. Is there a guide on how to replace them? As it looks, the bearings are pressed into the bed so the risk on damaging something is high on my oppinion. Any guidance is appriciated. 

Edited April 25 by Schoffra

[gr5 2,176]

I've only done bearings on UMO and possibly UM2, sorry.  But for those it was 4 screws holding the bearings.  Try google?

 

The thing is, if you remove the z screw, then you can test the bearings by just sliding the bed up and down.  It should be obvious.

 

Also look if the Z screw is crooked - shaped like a curve.

 

The z screw is triple helix so just measure with a ruler 3 threads.  Or measure 9 threads and divide by 3.