Micrometer inconsistencies in z-offset probing causing waviness?
Hi.
I've been doing some experimentation on finding a suitable z-offset value in my slicer for my kit MK4 printer. I occasionally have some issues with wavy first layers due to the z-offset being too low, and I've landed on adding +0.025 mm to the z-offset to eliminate the waviness / waves. Surprisingly enough, just 0.005 or 0.010 mm difference in z-offset is enough to cause or eliminate waviness in the first layer.
When printing many +0.025 mm z-offset samples to ensure consistency, I encountered a problem. The same piece printed with the same +0.025 mm z-offset are on the same print bed different in waviness (see attached picture). I guess this is due to the automated z-offset probing itself has some inconsistencies. (To clarify, I have not seen a pattern in previous prints of the right object being more wavy than the left object.)
I could in theory remedy this and just add a much larger like +0.05 mm z-offset to all my prints, but I'm concerned adding too much of a positive z-offset will lead to a decreasing print quality in other ways.
Have you faced this issue before? Do you have any tips or advice?
RE: Micrometer inconsistencies in z-offset probing causing waviness?
Be aware of this: Bed probing is not based on an accurate measurement of the nozzle height above the bed, but on the basis of the force that the nozzle exerts on the bed. And the nozzle does not have to be the same clean for each print in the row, and thus the dependence of force on the distance from the pad changes. And the measurement is carried out in an analogue way, and even there may be some inaccuracies in the evaluation. Hence the differences. They are small, but in conjunction with other influences, they lead to such results. There is probably no good advice here, given the circumstances.
RE: Micrometer inconsistencies in z-offset probing causing waviness?
Hi, I recently solved a problem with curling and waviness on the bottom layer by changing my retraction settings. The solution was supposed to address "oozing and stringing" but also addressed curling and waviness (much to my relief).
Some options can be found on this page:
https://help.prusa3d.com/article/stringing-and-oozing_1805
Good luck!
Graeme
RE: Micrometer inconsistencies in z-offset probing causing waviness?
Hi, I recently solved a problem with curling and waviness on the bottom layer by changing my retraction settings. The solution was supposed to address "oozing and stringing" but also addressed curling and waviness (much to my relief).
Some options can be found on this page:
https://help.prusa3d.com/article/stringing-and-oozing_1805
Good luck!
Graeme
Hello! Could you give some more information on what you did? I have a hard time seeing how retraction settings can affect waviness, especially since the objects I'm printing are just a flat sheet, there is alsmostno retraction as almost the whole thing is printed in one pass.
RE: Micrometer inconsistencies in z-offset probing causing waviness?
Check out https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/4254
Plenty of unhappy people with the same problem. In my case, adding +0.04 helps with the wavy patterns I see with PLA.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE:
Check out https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/4254
Plenty of unhappy people with the same problem. In my case, adding +0.04 helps with the wavy patterns I see with PLA.
I've done a whole bunch of testing and the results are a bit counter-intuitive. Having a z-offset of anywhere between 0.000 -> 0.015 mm leads to waviness on a majority of objects. Having a z-offset at 0.020 mm leads to roughly 25% of the objects having waviness. The counter-intuitive part is that increasing the offset (I've tried up to 0.045 mm in 0.005 mm increments) doesn't lower the likelihood of objects having waviness, it seems to be consistently around 25%.
The page you linked to shows a lower speed significantly decreasing waviness or even eliminating it completely. That might be the best solution.
RE: Micrometer inconsistencies in z-offset probing causing waviness?
All of this counter-intuitive. On my XL, which has the same load cell as a Mk4S, I have never, not once, seen waviness. I don't see it with ASA. Sure, we can adjust live Z, decrease speed, heat up the nozzle to be even with the bed temp, but that's all just band-aids.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Micrometer inconsistencies in z-offset probing causing waviness?
Hi, I don't yet understand why the retraction settings are effective due to my lack of experience, but my tentative conclusion is that it ensures more precise layering and cooling/adherence consistency.
I solved my issues with the attached retraction settings on a satin sheet, PLA filament, 65 bed temp and 215 nozzle temp, with brimming and organic supports.
RE: Micrometer inconsistencies in z-offset probing causing waviness?
I have experimented with print speed and printed a few pieces with 20 mm / s and 30 mm / s print speed on the first layer (the default value is 40 mm / s). Printed with no change to the z-offset.
My findings are that the waviness does not disappear with a lower speed but it makes them less visible. At 20mm/s speeds they are only realistically visible if printing an extremely thin / transparent object or if you're looking for them). At 30mm/s speeds, they are still quite visible but less so. My guess is that since the nozzle is moving so slowly, it has time to squish out all the waves that are appearing but it doesn't actually prevent them from occurring.
Printing at such a low speed however leads to the filament creeping up / blobbing on the nozzle, eventually causing a blop to fall off or perhaps stringing (although I didn't personally see any of that). That might be an extra problem in my case since my enclosure temperatures are so high (30 C).
It could very well be that the best solution is just to print on a textured sheet, since no waviness are visible then. I'm not the biggest fan of the texture that the textured sheet gives though. (I have done almost all my testing on the satin sheet.)
After printing around 50x test sheets I'm done testing. Printing at 20 mm / s makes waves less visible, but raises the risk of filament blobbing on the nozzle which is in my opinion even worse. The only solution I've found that consistently works and doesn't come with a drawback is printing on a textured sheet (although that's not actually solving the problem, just hiding it).
RE: Micrometer inconsistencies in z-offset probing causing waviness?
Hi, I don't yet understand why the retraction settings are effective due to my lack of experience, but my tentative conclusion is that it ensures more precise layering and cooling/adherence consistency.
I solved my issues with the attached retraction settings on a satin sheet, PLA filament, 65 bed temp and 215 nozzle temp, with brimming and organic supports.
I tried these retraction settings and they didn't eliminate the waviness for me. I have no idea why they worked for you, but congratulations on finding a solution I suppose! 😄
RE:
Fact is that ‘always perfect first layer’ as Prusa advertises the MK4/XL series is wishful thinking (or over optimistic marketing hype ), if we demand a really flawless ultra smooth fist layer.
In real world, the printing bed is never flat enough to allow mesh leveling correct perfectly those small bumps and hollows. Besides, as the bed warms up, thermal expansion modifies slightly the shape of the bed, and the mesh leveling performed before the print starts is no longer accurate. This is specially noticeable on prints with a large contact area with the bed, where the first layer takes a lot of time to complete. Apart from that, of course, there’re the logical tolerances between loadcell calibration on different printers.
RE: Micrometer inconsistencies in z-offset probing causing waviness?
Very interesting! With so many variables it's difficult to conduct any kind of controlled study. As Edison said... he didn't fail miserably at creating a light bulb, but succeeded at finding so many ways NOT to create a light bulb. 🙂
By the way, I read on one of these forums that keeping the enclosure doors open is recommended to keep the temperature down. I don't know if this is important, but I've started following the suggestion.
Good luck!
RE: Micrometer inconsistencies in z-offset probing causing waviness?
It sounds like you’re encountering some subtle inconsistencies with your z-offset probing, which can definitely affect the first layer quality. It’s normal for small differences in z-offset to cause noticeable waviness, as you've observed. Automated z-probing can sometimes introduce slight inconsistencies due to factors like bed leveling, sensor calibration, or even slight temperature variations.
One thing you could try is manual mesh bed leveling if your printer supports it, as it can help account for variations in the bed and improve consistency. Additionally, make sure your probe is clean and properly calibrated, as dirt or wear can lead to inaccurate measurements.
If you’re using a mesh bed leveling system, increasing the number of points probed may help to get a more accurate result across the entire bed. You’re right to be cautious about adding too much z-offset, as it can impact overall print quality. Instead, try adjusting the bed leveling or experimenting with smaller, more incremental z-offset changes to find a sweet spot that works across your prints.
Alice Carry