MK2S started to show Ringing/Ghosting

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hendrik
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Joined: Fri Jun 16, 2017 8:04 am

Re: MK2S started to show Ringing/Ghosting

Post by hendrik » Sat Jun 17, 2017 11:23 am

The printer is still on the same concrete slab on the same table. So no change there. I tried to keep everything else as it was.

I did yesterday and today adjustments on the bearings of the Y axis: More tension on the bolts, Less tension on bolts and I swapped them. It's now a bit worse then before as I wrote above.

I started to use another test object, because the benchy takes too long to print.

This are the results (top left was yesterday before the mods, i.e. similar setup as the right hand benchy in my first post, then after each modification I printed one after new XYZ calibration):

Along X:
along X.JPG
along X.JPG (268.54 KiB) Viewed 1803 times
Along Y:
along Y.JPG
along Y.JPG (302.22 KiB) Viewed 1803 times
It still is worse than before :(

So, my first conclusion is that I might not the mount of the Y axis bearings that do the ghosting, it just amplifies it.

I see 2 possible next steps:

A. Lower Y belt tension (I did not change that for a long while). Why changing it now? I think the Y carriage runs now smoother than before and maybe the high tensions of the belt cause the ghosting.
B. I change something on the extruder/X-Axis. But then I do not where to start. I rechecked everything I can not identify anything there that is "wrong" and where to start.

I think I will go with A in the afternoon. Any suggestions are highly welcome! :)

hendrik
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Joined: Fri Jun 16, 2017 8:04 am

Re: MK2S started to show Ringing/Ghosting

Post by hendrik » Sat Jun 17, 2017 2:40 pm

Loosing the belt by 3 teeth (6mm) did just increased it a bit more.

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brotherchris
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Re: MK2S started to show Ringing/Ghosting

Post by brotherchris » Sat Jun 17, 2017 4:21 pm

Have you messed with re-setting the belt pulleys? I have noticed sometimes the grub screw is not exactly square with the flat spot on the motor shaft.

hendrik
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Re: MK2S started to show Ringing/Ghosting

Post by hendrik » Sat Jun 17, 2017 6:21 pm

Looked right, however I loosened the pulley and and carefully put it back - same result :(

ronka
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Re: MK2S started to show Ringing/Ghosting

Post by ronka » Sat Jun 17, 2017 8:27 pm

hi, did you try printing at a slower speed and/or adjusted the acceleration and jerk settings?
also constuctionwise; the more rigid the printer is build, the higher the risk of artifacting..

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brotherchris
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Re: MK2S started to show Ringing/Ghosting

Post by brotherchris » Sat Jun 17, 2017 9:16 pm

Just out of curiosity, If you print a model from Prusa that came on the SD card, do you see the same issue. What Slicer are you using?

hendrik
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Re: MK2S started to show Ringing/Ghosting

Post by hendrik » Sat Jun 17, 2017 9:36 pm

Hi, thanks for your input!
ronka wrote:
Sat Jun 17, 2017 8:27 pm
hi, did you try printing at a slower speed and/or adjusted the acceleration and jerk settings?
Yes, if print slower the ripples are much less pronounced.

I printed these test cubes above with 0,35 layer height and vase mode with 20, 30 and 40mm/s. The ripples are much softer (you actually have to look for them) and invisible on 20 mm/s.

However the point is that I have a benchy I printed weeks ago and now the exact same gcode and the same filament shows a lot more ripples (see 1st post). So I did messed something up and have no clue what. I did not tweak the firmware, and I didn't alter any settings on the printer related to acceleration, jerk, steps etc. The only thing that came to my mind that might be software related is, that I'm not sure if the old benchy was printed with 3.0.10 - I'm using 3.0.11 since it was released.

EDIT: When answering the post to brotherchris, I saw the date when I sliced the benchy. So it was most likely 3.0.10. 3.0.11 was released on 19th.
ronka wrote:
Sat Jun 17, 2017 8:27 pm
also constuctionwise; the more rigid the printer is build, the higher the risk of artifacting..
Can you elaborate this more? Do you suggest that I loose something?
Last edited by hendrik on Sat Jun 17, 2017 9:42 pm, edited 1 time in total.

hendrik
Posts: 22
Joined: Fri Jun 16, 2017 8:04 am

Re: MK2S started to show Ringing/Ghosting

Post by hendrik » Sat Jun 17, 2017 9:40 pm

brotherchris wrote:
Sat Jun 17, 2017 9:16 pm
Just out of curiosity, If you print a model from Prusa that came on the SD card, do you see the same issue. What Slicer are you using?
Do you have any model from the SD card in mind that would be a good subject for ripples (and does not take ages to print)?

The benchy was sliced with:

Code: Select all

; generated by Slic3r 1.34.1-prusa3d on 2017-05-13 at 07:32:18

ronka
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Location: Holland

Re: MK2S started to show Ringing/Ghosting

Post by ronka » Sun Jun 18, 2017 1:18 am

ronka wrote:
Sat Jun 17, 2017 8:27 pm
also constuctionwise; the more rigid the printer is build, the higher the risk of artifacting..

Can you elaborate this more? Do you suggest that I loose something?
okay here it comes: :ugeek:
most ideally your printer doesn't make any vibrations when printing but thats out of the question because mass is jerked around and thats te ringing jou see in your print. if the marks where constant troughout the print it would most likely be microstepping or belt issues.

almost any vibration is transferred via the frame into the nozzle or the bed and so into the print you make.
not a problem for the internal stucture of the print, but more so in the outer shell.
if this vibration is dampend before it reaches the plastic it cannot influence the quality anymore, as you already tried loosening the belt could be such an action.(not too loose i hope :roll: )
back to rigidity; for instance: the whole printer can be so stiff that its being supported on 3 corners in stead of all 4 making vibrations possible in the corner thats not being supported..
if the frame would flex a bit the 4 points will be supported eliminating that source..
the printer could stand on a wobbly table, the printbed supported by loose springs(ban the springs!!, i did..), a very heavy x carrage, slipping pully on the stepper, worn out bearing, misallined rods, contamination of sliding components(clean and lubricate!!)... the list goes on..

even the use of different building materials has effect on the flexability of the frame. (aluminium with plastic parts dampens more than all aluminium, all plastic flexes too much) --->keep in mind flexing.. not loosening. ;)

all this aside; before wrecking the hardware... try printing outside shell at 20mm/s and try lowering xyjerk in marlin to 2.0.

hendrik
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Joined: Fri Jun 16, 2017 8:04 am

Re: MK2S started to show Ringing/Ghosting

Post by hendrik » Mon Jun 19, 2017 2:49 pm

Hi ronka,

thank you for the explanation.

Before I start to modify my settings I want my printer to be as good as it already has been before with the same settings. ... Yes, I'm stubborn :mrgreen:

So I will go on checking everything again more systematically. The problem is that I had to disassemble a lot to check the bearings as PR asked me to do. So there are many steps involved. This means weeks of testing :)

I was just hopping that somebody could point me to the main missteps that will cause/increase ghosting when assembling an MK2(S).

BTW: Loosening the belt didn't help, it increased the ghosting slightly.

I noticed that Y idler holder wasn't tight anymore. However tightening it according to the assembly instruction didn't change quality at all (at leat at the test print cubes).

The LM8UU PR uses are of poor quality. I got 4 spares from them: One is quite tight on the rod, 2 medium and one very loose. I'm wondering how we get such good prints out of the MK2 at all. :)

I guess tighter should be better in the is case?

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