belt ripples artifact
Hi. I have belt ripples artifact (sometimes called salmon skin), in general - vertical pattern which exactly matches belt teeth distance. Printer - no mods, just vcore 3.1 300mm kit. I discovered that it is more strong during Y movement, but also very visible on X. What I found strange - it is stronger on movements from Ymax -> Ymin and Xmax -> Xmin, so on different sides of the model it has different visibility, like that:
113 Replies
So:
Xmin -> Xmax: this problem does not exist/invisible
Xmax -> Xmin: visable but not that bad
Ymin -> Ymax, visable, but less visable then Xmax -> Xmin
Ymax -> Ymin: very visible
Printing settings - just default one from Prusa slicer for RatRig VCore 300mm
1st photo: best looking side (Xmin-> Xmax), 2st photo: worst looking side (Ymax->Ymin)
my shaper graphs
I did follow guide to align gauntry, tried to print on concrete floor to exclude table from the equation, reassemble entire frame
Also I noticed that if I move Y by hand, print head viggles left and right a tiny bit (maybe by 1mm or so)
but otherwise movement seems to be nice and smooth
either belts too tight or bad bearings in one of your linear rail carriages
Hmm, bad linear rails is unexpected option, how would I test? By hand they seems to move nice and smooth(without gauntly attached)
belt tension can rack the carriages on the rails, causing them to 'stick' a little here and there. any uneven drag would cause print artifacts
Theory is cool, thought it does not explain how to fix… I guess I will start with lower belt tension
just went back and looked at your pics...since that surface ripple 'continues' the whole way along the side...that's a belt tension match issue compared to X axis. which is too loose or too tight.... can't guess.
you'll notice the spacing appears to match the cogging of the pulley belt teeth
hm, I tried to lower belt tension ,belt ripples are a lot less visible (I still can see it under harsh light), but Y shaper graph looks quite noisy, suggested accel is very low
I still have this issue but lowering the tension made it better I have the suggestion that you make sure that you have good squareness that I probability prob also my problem bc I have different tension so binding appears or so. Also my right motor mount makes weird noises
And maybe lube the rails
interesting that X accel suggestion is lower than Y...it's usually the other way around. Plus that Y graph doesn't look so hot. (second hump)
Yeah that’s it’s dragging a lot
Eh doesn’t seem like that with the recommended algorithm?
Ehh, I rebuilt frame twice... Did not help much. (I had ripples before and after)
Without the belt everything moves smooth right ?
Yep
Hmm
And I did follow guide to align gauntry (in which you realign rails)
And your rails are all lubed ?
Maybe we both got bad bearings
When moving the y axis does your toolhead like move abit?
yep
yes, it moves by ~0.5mm left and right, If I move it really slowly, but I guess that is normal?
So belt tension did not really "fix" it for you too, that is weird...
I ordered FMMM mod, motor decouple mod, toothed idlers for front of xy-joint and new belt and new pulleys will see if it would help. But delivery would take 1-2 months xD
Maybe everybody have it, and do not see a problem in it? I previously had totally different printer (HEVO), which was used to print parts of that printer, and I can see same wavy pattern, despite the fact that it used thinner belt, and rods instead of rails.
@Helge Keck did you ever have such artefacts?
try another speed
this look slike classic gt2 belt artefacts
try also too loosen your bekts a bit
retune input shaper
But why is it direction dependent?
Yep, did it, check last graphs
Then now I ask classical question, if 140mm/s creates so bad artifacts, why’s is it in default config😂
there are so many factors that play a role, no profile can catch all of them
every printer has a speed and acceleration goldilock zone
this depends also heavily on your choosed stepper driuver profile
you need to find the speed goldilock zone
Understandable, so - the fact that intensity of artifact changes with direction does not necessarily mean bad mechanics, it could be just bad speed?
you can use the tuning tower command from klipper to test this easily
Will try, thanks.
Do you have some paper in reach which describes it? Just curiosity, as I heard about it, but can’t google.
can you bing?
Got it, no more questions. Thanks for reply 8)
Did you read it? (Just found it, and that guide seems to be godsend, will follow it and update status on weekends) https://ellis3dp.com/Print-Tuning-Guide/articles/troubleshooting/vfas.html#vfas-with-2mm-spacing
this is a well known guide
Nope
Didn’t really searched for it
But I thing when moving the y the toolhead jitters and makes those waves
i now after folling the guide got those
i have this 125hz peak
That’s… interesting, maybe you just forgot to tight something?
Don’t think so
That’s how my prints look
One if them looks quite fine
adverse-sapphire•2y ago
I do believe my prints looks the same, so it seems quite common issue. I'm curious can it be from belts teeths against bearings pulleys on x gantry
Any ideas
Nope, my current plan is to stick with low belt tension(though it means very low accel) and wait for parts for FFFM mod, toothed idlers and motors decoupler mod, hope it would help😅
I tried speed calibration, but it does not got worse at higher speeds
Bottom is 100mm/s, middlet 150mm/s, top 200mm/s
doesn't look like the ripples are there at the bottom section (100mm/s?) ripples start around 1/4 of the way up from the bottom
There are a lot less visible, but unfortunately on the opposite side of the tower it looks opposite, more visible at 100mm/a and less visible at 150mm/s +
Not best photo, so just trust me😅
i highly suggest to use marcs linear movement analysis to find out your speed goldilock zones
GitHub
GitHub - worksasintended/klipper_linear_movement_analysis
Contribute to worksasintended/klipper_linear_movement_analysis development by creating an account on GitHub.
Oh, there is such thing…
Is there guide how to read this graphs? README seems to tell only how to generate them, and only tiny bit about their meaning.
Okay, so, I run linear movement analysis, how to read it? X:
Y:
A:
B:
sensitive-blue•2y ago
first one should look like the one posted on github, forth one is telling you at which speed you have the lowest vibration. ( in your case, 140-160 it is the best speed)
Try this
clean and lube the linear rails
set stealthchop_threshold to 999999 or 0 (run graphs after each setting and see which one works better)
Set x and y motor current to 1.4 or 1.8 and run graphs
https://discord.com/channels/582187371529764864/1112836488061788300
Thanks for suggestions
sensitive-blue•2y ago
motors to that v only if you have cooled steppers, if not do 1/1.4
And did you guys got it fixed ?
Ok it seems to be alinging pretty whell with the belt
Okay so I had a different problem and I managed to fix these along the way.
My issue was that the belt was touching the top side of the pulley, this happened because at some point the pulley came loose from the motor and probably moved there.
I received parts for FMMM and motor decoupler, need some time to install that, probably in weekend
nice tell me how you get along
any news?
WIP, need some time, have only toothed idlers installed and motor decoupler assembly done, need to finish installing of FMMM mode and route belt
Update, mods are installed.
graceful-beige•2y ago
how about the mod?
Struggling to make my right belt (lower one) stop moving up and down on motor pulley… when gantry is moved forward it goes down, when front - up.
Moving left and right has the same effect, I already reassembled right motor cage twice, and visually checked for all shims be in place
Looking forward to see your results. Facing the exact same issues. Higher print speeds on the external perimeters reduced the issues, but not solved them. Even though I'm using input shape I'm facing some more pronounced artifacts which seems like ghosting, but align with the belt pattern
so i will try reaplcing the belt aswell as the bearings
Ok how did it behave any fix?
Nah, mods did not help at all, belt replacements- did not test yet (I have done mods and belt replacement separately)
Ugh i might rebuild it but now square
I don't think the frame has anything to do with the issue
The belt might nut nur perfectly in the middle maybe hits a side of the motor mount
I thought that too, that's why I tried to listen at the motor mounts during movements. In my case there was no noise which could indicate that the belt is rubbing
stormy-gold•2y ago
did u checked the belt tensions? if it is to tight it can cause a sort of ripple too. Saw that on a Voron from a friend of mine.
Are there any reference values regarding the frequency or so?
sensitive-blue•2y ago
Sort out the "B" graph, that is the problem
switch motor pulleys and see if B looks good and A bad
stormy-gold•2y ago
U can calculate it with math
Maybe this is making the issue it’s like moving up and down
stormy-gold•2y ago
That moving is not intended. U should check where it. Ones from. Maybe a crooked idler bolt.
that top belt is toast! it's all ripped up along the top edge. It's been riding on the edge of the idler or scraping your corner printed parts. The only thing that makes a belt move up/down is miss alignment of two pulleys along the belt path...either not aligned on the same plane, or one idler/pulley is not on the exact same axis as the adjacent one.
the damage to the belt alone could cause the 'rise fall' as you note, as one edge is longer than the other now (belt is no longer straight. If laid out on a table, you'd see a 'dip' in the line as the belt has been stretched along one edge only
Yeah I will change it but it can’t make those sinusoidal motions
Okay, update after vocation - swapping the belt and doing fmmm and decoupler mode gave some results, not this is how four sides looks like
I would say, some new artifact appeared - unaligned horizontal waves, but aligned one became less prominent
Oh yea - swapping out the belt seems to had most noticeable effect (old one - original from ratrig, does not have noticeable problems, new one - ordered from triangle labs, they state - it is original gates 2gt belt)
I am happy with results, I would say
I did change the belt from ratrig to gates belts made only an minor change but I can see these marks any idea what I could be
Se the line on the belt maybe I will change the bearing
are ALL the bearings in that stack rotating freely? those lines line up perfectly with the three bearings stack. The bottom of that middle bearing looks shinier than the rest which is a bit odd. you'd think they'd all be the same
When I change the belt it pressed against then with a screw inside and they where freely to rotate
Those lines are simply where the belt is not in pressure contact with a bearing surface right at the bearing separation points. It is not common, but should not be an issue. Do/can you wipe the lines away (lightly clean the belt with a link free cloth NOT any chemicals)
exotic-emerald•16mo ago
Hello. I tried to install it but it stayed like this for 1 hour. I am using raspberry pi3b+. I don't use ratos.
sunny-green•16mo ago
I had this problem on a printer once too. i used aftermarket gates belts on which were not what came with the printer originally - only after also switching out the pulleys and idelers to original gates ones the problem was fixed. They have a slightly different tooth shape and i blame the combo of the gates belt with a non gates toothed gear.
@maba_kalox ever fix this?
Had the same issue and it may seem I have fixed it: throw the shitty bearings and belts out. Ratrig uses so bad quality parts in this case
@gizzle13 the linear rail carriages also or just the idlers?
Rail and Idler bearings for fushi bearings
Thanks. Will try it.
Hello
Did you solve this problem?
I have same on my virin trident https://reprap.org/forum/read.php?397,894253,894538#msg-894538 Other people can't solve it on other printers
What is the cause of magical random ripples on the Core XY printer?
Hello Help me please. I have voron trident like printer. My 1st custom assembly. CONFIGURATION • 4040 (v-slot) and 2040 (t-slot) frame with corners and corner outer plates; • RDBB 500mm rails (12mm on X axis); • powge pulleys and idlers, 6mm gates belts (tensioned at about115-120 Hz), fushi bearing
Hello
Any success?
Im currently changing bearings
Until now not really
Yes, much better. However there were multiple things i tried to get there. Changing my XY idlers to aluminum, replacing the bearings, and loosening the belts.
How loose and how did you measure it?
Very loose and tightened only a bit till graph somewhat resembled the example. Then didn’t try too hard to make it better since it printed better than when my graphs looked good but belts too tight.
Hello
What bearings did you buy?
Fushi Abec 7
I found a way to reduce the artifacts for me. The solution was more speed. Normal print speeds are too slow for the vcore
Nope, some minor changes. But overall same - bigger ripples when moving from Xend to X0 then from x0 to Xend and same for Y axis
I second this. Tried 90, 120, 150mm. Belt artifacts there. Did 200mm, gone, nada, not here, whoosh. You could try and run resonance testing during moving. There was such an option and find the speeds where it resonates less from the motors
90 was second best. Maybe if I went something in the 50 for the outer wall, that could also do the trick, but 100-200 is a nono zone it seems. Also it bring other artifacts, that are negated during higher speeds. Less temperature helps with filament being more matte, thus hiding everything
Well I tuned my vcore quite good at 220mms outer perimeter speed :kekw:
Perfect! My only issue are sharp corners. No matter what, they bulge a tiny bit
Pressure advance
No way! You sure?!? I cant believe it. It seems the last sevceral towers, lines and patterns were just child play. No matter what would assume i have taken the steps
Tbh, the pattern etc are ass. I am mostly set a value by printing some real parts with the speeds I'm using.
Yeah, true, but I also used the tower which accurately represents real printing and that did not have a good value
I need to play with smooth time tho
@Maba_Kalox What you saw is a result of the belts.
Now, that can be transmitted from belt to print through several different pathways - but to go looking, you need to consider what mechanical interfaces there are between the belt and the rest of the machine.
First up, you need to consider the interface between the belt and the pulleys.
The profile of the belt teeth and the pulley teeth MUST match precisely, or you will see that problem.
If your pulleys were manufactured on a failing production tool, you might observe that the profile of the pulley teeth is different from clockwise to anti-clockwise. That would explain your issues being more pronounced one way than the other.
Belt tracking is adjusted by setting the relative angles of the pulleys the belt runs on. If you want a real-world upscaled example, go look at a linisher belt and see how the tracking mechanisms work. They literally adjust the angle of the front pulley to make the belt 'walk' from one side of the pulley to the other and correct any drift.
Another issue is that the pulleys for a toothed belt MUST be arranged such that the pulleys and belt are all in the one plane. Otherwise you WILL have the belt 'walking' and rubbing on the sides of the pulleys and wearing.
Once you've sorted out those design interface problems, you can progress to the mounting of your pulleys.
Pulleys should run straight and 'true' - especially for positional control systems. Otherwise you will see artifacts like you have described.
Now, here's the thing - it's one thing for a pulley to run 'true' when it's got no load on it. It's another to make sure it's true with a belt on it.
This is why you need to have a solid mounting point for your pulleys - at the very least, you need to use a bolt with a shank. Best would be a turned or ground rod, secured at both ends with a press-fit tolerance.
After you've sorted all that out, then you can think about belt tension, elasticity, and tooth deformation due to tension and loading.
Now, there is a different pathway - it could be the stepper motors.
However, while the profile of the visual artifacts matches the spacing of the belt teeth exactly, I am disinclined to believe it would be the stepper motors.
Some random thoughts....
Belts moving up and down the pulley can be an indication that your motor shaft is not running true.
To loose or too tight belts can increase racking issues. Racking can cause repetitive bind and release of your Y rails, which will show up as repetitive artifacts on faces parallel to the X rail
Tighter belts are more likely, I think, to expose issues with pulley bearings. Bearing stacks work better than the original pulleys and last longer.
I also wonder if your X carriage might have some free play? Can you rock your print head forward and back with light pressure?