Horizontal lines (2 lines) almost at a specific height

[jeffsjunior 0]

I am having this weird problem that at almost all prints 2 horizontal lines appear.

I printed a tower with 0.2mm layer height and the lines did not show up, however, as you can see in the picture the other 3 prints had the same problem almost at the same height. I say "almost" because other prints have those lines a little bit above or below the ones you can see in the picture.

It seems that the Z stage cannot move one layer so it adds another layer at the same height and then it skips one layer, but it does not explain the double horizontal lines, so I am not sure if this is the problem.

I removed the Z axis and cleaned as much as I could, but it did not solve the problem. I still can see 2 horizontal lines.

Soooo, does anyone have a good idea how to fix that?

[gr5 2,167]

You are on the right track. These kinds of lines can be caused by many things (filament tangles, z stepper drive too hotO) but with this kind of consistency and on models of very different amounts of plastic per layer - the only explanation left is Z stage issues.

Fortunately you know how take everything apart. Start by sliding the bed up and down many times with power off and trying to feel these 2 spots. Your hands are amazingly sensitive and hopefully you can feel this. If you can feel it then you have a check that takes a few seconds to verify if it is fixed or not versus printing for an hour.

It could be bad screw, bad nut, bad z rods, bad bearings, or other interference (does spool holder or anything else touch the bed? Often the spool holder sticks through enough to hit the bed as it passes by).

Usually these things can be fixed without getting new parts but new parts can be amazingly cheap. If your printer is less than a year old you should be able to get the faulty part replaced through warranty but none of these parts costs very much.

Also try loosening the screws that hold the bearings a bit and see if it's now smoother and possibly you need to somehow make the 2 rods more parallel or maybe just loosen and retighten the bearings.

There should be no oil or grease on the vertical rods as that can get into the bearings (along with dirt/dust). The screw of course needs a little grease.

Is this a new printer? Or is this a recent problem on an older printer?

[jeffsjunior 0]

Thanks for the reply. I bought it last year, but it is still in the warranty.

Since this only happens at only 2 specific spots, I guess the problem is with the Z axis

This is kind of a new issue, I left it stopped for 3 moths, I guess, (covered) and this problem happened. I will try loosening the screws ( never tried this) and check if I can fix it by cleaning specific spots.

Thank you

[gr5 2,167]

I left it stopped for 3 moths, I guess, (covered) and this problem happened.

that's fantastic news. It's probably just dirt on the Z screw. Clean it completely with WD40, dry it and then put on some fresh grease (just a pea sized drop).

[jeffsjunior 0]

while I dont buy the WD40 to clean it properly, I decided to use a toothpick to reach the difficult corners of the Z-axis to remove some of the old and dirty grease that was attached there, and it solved the problem for one print, but it came back again a little bit better than begore. Theferore, it is dirty grease for sure .

Do you have and advice how to clean it properly? reaching all the hard spots to clean? I just used a soft cloth and it didn't help much.

Thank you

[ultiarjan 1,223]

talked to a guy from Ultimaker about this once... he just pushes a thin cloth in the grooves with a thumbnail, then uses the "move bed" function a few times to go over the whole z axis.

[neotko 1,417]

For fast cleans I use a toothbrush with bike black grease/oil and use it while homming to push any dust while greasing the screw.

[JohnFox 25]

Make sure the Z axis pillars are completely clean, ( no oil ).

[jeffsjunior 0]

For fast cleans I use a toothbrush with bike black grease/oil and use it while homming to push any dust while greasing the screw.

 

This is such an awesome tip, thanks

[jeffsjunior 0]

Maaan, so many variables to analyze.

I cleaned the Z axis with a toothbrush, i didnt remove it, just brushed it a little bit at the height that I am having the problem, and the print was awesome.

However, I also printed it over USB, and downgraded the firmware to CURA 15.04.03 because when I updated to the CURA 15.04.06 the "scar" got worse and became a fully missing layer.

When I stop to think, it just seems a coincidence, I don't think the firmware or the SD card has anything to do with the problem, but it costs nothing to ask, so I am asking.

Do you all think it might be the firmware or the sd card? or everything together?

[neotko 1,417]

Don't forget the heat variable that @gr5 pointed.

I had a lot of problems the past summer because of that. For this summer I did install heat sinks on all stepper chips.

Edited June 20, 2016 by Guest

[jeffsjunior 0]

It is not the heat for sure because here where I live, it is really hot ( brazil ), so I always use it with a fan blowing air underneath the printer (ahahahha).

Update: After removing the Z axis and cleaning it very carefully with a toothbrush and an old T-shirt, I tested the linear bearings without the Z axis and it seems that the problem is the linear bearings.

I can feel a spot where the bearings resist, just a little bit, to move near the height where I have the problem. I rotated the linear bearings, just to see if it would get better, cleaned the rods (again) and carefully tightened the screws one by one while I was moving the bed up and down (again).

Now it feels a little bit smoother, after greasing the Z axis again, I will try a few prints to check if the problem is gone "forever". If it is not gone, I think I will have to buy/ask ultimaker new linear berings or new rods, or both, I don't know ahahaha.

[neotko 1,417]

Check this just in case

https://ultimaker.com/en/community/11123-z-axis-layer-error?page=last#reply-130203

[JohnFox 25]

Keep the pillars really clean by wiping with a paper tissue from time to time.

 

It is not the heat for sure because here where I live, it is really hot ( brazil ), so I always use it with a fan blowing air underneath the printer (ahahahha).

Update: After removing the Z axis and cleaning it very carefully with a toothbrush and an old T-shirt, I tested the linear bearings without the Z axis and it seems that the problem is the linear bearings.

I can feel a spot where the bearings resist, just a little bit, to move near the height where I have the problem. I rotated the linear bearings, just to see if it would get better, cleaned the rods (again) and carefully tightened the screws one by one while I was moving the bed up and down (again).

Now it feels a little bit smoother, after greasing the Z axis again, I will try a few prints to check if the problem is gone "forever". If it is not gone, I think I will have to buy/ask ultimaker new linear berings  or new rods, or both, I don't know ahahaha.