Regular surface distortion pattern towards end of larger first layers VC4

UPDATE 2024-10-15:

This post has become more like a working group channel, currently focussed on investigating gantry bowing induced by heat from the hotend and its fan.

A summary can be found here: Regular surface distortion pattern towards end of larger first layers VC4

Original Post:

This post follows on from https://discord.com/channels/582187371529764864/1223286652949106748/1293290320083292214 (the two images of a first layer with a circular hole in the middle) and subsequent conversation on #v-core-4. The first layer looks great to start with, then after a while a regular wave-like distortion pattern shows up. In the attached image from https://discord.com/channels/582187371529764864/1223286652949106748/1293296476180447324 showing a print in progress, the distortion started after about 20 minutes into the print. This issue is affecting several users, and occurs with fully up-to-date RatOS as of 8 Oct 2024.

chicken•10/8/24, 9:23 PM

party time

sardonumsei•10/8/24, 9:23 PM

Following as I have this same issue and have to babysit my first layer and bump z offset incrementally.

CrashTestCharlie / VC4 400h•10/8/24, 9:30 PM

Post for follow, this is the most annoying thing yet

Mmmm1223334444•10/8/24, 9:31 PM

I owned comcrow t500 before this and same problem

tg73OP•10/8/24, 9:31 PM

So, some things I'd like to double check myself (and others to check would be great):

Observe z stepper movement (eg, look at the leadscrew couplers) while the first layer is going well. Then continue to observe once the distortion pattern starts. Does the z stepper motion seem different, and does it seem to be in sync with the distortion pattern in some way?
Can the regular wave pattern we're seeing be recreated early on during the first layer (where it normally looks good) by intentionally by baby stepping z too low or over extruding?
Can the problem be reproduced using PLA on an unheated bed? This would help rule out some thermal issues.
How repeatable the issue is for a given model? Does the distortion start at the same place and have the same pattern each time? Does the position of the model on the bed have any effect?

CrashTestCharlie / VC4 400h•10/8/24, 9:33 PM

Does it happen after a beacon settings wipe?

chicken•10/8/24, 9:33 PM

work has been a zoo for the last few weeks so I have not been around discord as much. With these latest code changes is it still recommended to run the Zs with a microsteps of 16?

[stepper_z]
microsteps: 16
[stepper_z1]
microsteps: 16
[stepper_z2]
microsteps: 16

[stepper_z]
microsteps: 16
[stepper_z1]
microsteps: 16
[stepper_z2]
microsteps: 16

Cchicken work has been a zoo for the last few weeks so I have not been around discord as ...

tg73OP•10/8/24, 9:35 PM

This was related to gradual z drift that Mikkel was investigating. I don't know the current state of this issue - I looked throught #ratos-development to follow the conversation but found no conclusion. My machine is currently stock in this regard.

CCrashTestCharlie / VC4 400h 5. Does it happen after a beacon settings wipe?

tg73OP•10/8/24, 9:38 PM

As a point of interest, yesterday I updated ratos and redid beacon setup from scratch. I'm not using the contact-based correction mesh. I've seen this first layer issue since I got my machine printing weeks ago and I still see it now. What does seem to now be fixed with the recent ratos fixes is that the first layer is consistently good to start with - I don't need to babystep z at the start of every first layer.

chicken•10/8/24, 9:42 PM

can everyone that is adding information to this thread let us know what size bed you have just so we can see how much this varries between printer sizes. I know with VC3s, 300s were mostly immunie to this type of issue while 400s had it a little and 500s had to be preheated. On my unenclosed vc3.0 500 even printing PLA at a 60c bed required my to preheat for 20+ minutes to get anything decent on the first layer. That was with a SuperPINDA. VC4s are ~100mm larger x gantry for a given size. So a VC3 400 = VC4 300, etc. I am on a VC4 500 that I'll be testing with

tg73OP•10/8/24, 9:43 PM

I think one thing that's not been discussed as a potential cause (that I've seen) is irregular extrusion. I think we should be careful not to get overly focussed on any one possible cause and keep our minds open - notably, it's easy to get very focussed on beacon and meshing. Of great interest is @mmmmssss1993 comment Regular surface distortion pattern towards end of larger first layers VC4 that they've seen it on a comgrow T500 - a giant bedslinger with an inductive probe (as far as I can tell).

sardonumsei•10/8/24, 9:44 PM

I have a 400

tg73OP•10/8/24, 9:44 PM

I have a 500.

Mmmm1223334444•10/8/24, 9:45 PM

500

CrashTestCharlie / VC4 400h•10/8/24, 9:46 PM

400

Cchicken can everyone that is adding information to this thread let us know what size bed...

tg73OP•10/8/24, 9:46 PM

I can't get to my printer right now, but the first thing I want to try tomorrow is PLA with unheated bed. I reckon the outcome will bisect the problem space.

Ttg73 I think one thing that's not been discussed as a potential cause (that I've seen...

Mmmm1223334444•10/8/24, 9:48 PM

My first printer was elegoo neptune 3max and its first layer was always perfect with bed size of 420x420. Its also 300€ printer no klipper. I have no clue what these klipper printers (t500 and rr) do wrong.

Mmmm1223334444•10/8/24, 9:50 PM

Wild guess is it possible that when printing toolheads heat rises to bowden tube and presoftens filament causing overextrusion?

Mmmm1223334444•10/8/24, 9:52 PM

No that cant be the case

CrashTestCharlie / VC4 400h•10/8/24, 9:53 PM

Also what's the filament that you're running when you noticed this?

CrashTestCharlie / VC4 400h•10/8/24, 9:54 PM

For me it's petg, I don't remember pla being this bad

sardonumsei•10/8/24, 9:54 PM

ASA, ABS, PETG. I have not done really large PLA prints.

tg73OP•10/8/24, 10:04 PM

It was petg recently, but before that I've been using PLA almost exclusively.

CrashTestCharlie / VC4 400h•10/8/24, 10:32 PM

Alright. I deleted the beacon stuff from printer.cfg, and reset the vars in ratos-variables.cfg. Saved and restarted, check updates, there are none. Going to unload filament, then do a full beacon config. The defaults for ratos-variables.cfg are these, if anyone is playing along at home

nozzle_expansion_applied_offset = 0
nozzle_expansion_coefficient_multiplier = 1.0
nozzle_expansion_coefficient_t0 = 0.06
nozzle_expansion_coefficient_t1 = 0.06

nozzle_expansion_applied_offset = 0
nozzle_expansion_coefficient_multiplier = 1.0
nozzle_expansion_coefficient_t0 = 0.06
nozzle_expansion_coefficient_t1 = 0.06

CrashTestCharlie / VC4 400h•10/8/24, 10:37 PM

oh, and a cold pull

DapperDangus•10/9/24, 2:20 AM

Wanted to jump here and be apart of this discussion. Hopefully I can help or shed some light on what I’ve tried to do. In my experience, I have tried to do a full first layer quite a few times. I have tried TPU with 35C bed, PLA at 60C, ASA at 110C. Each time I soaked for at least an hour and a half. I even tried PID tuning the bed and extruder after the heat soaks to see if that helped. Didn’t matter what I did, I had to adjust z offset through the whole layer but usually gave up about 1/3 to 1/2 the way.

That led to me getting a toro tube because I figured maybe the gantry was flexing differently as it moved from the front to back. I did these tests both before and after hot tightening my rail. Unfortunate to see tg73 having the same issue, thought you had a toro.

CrashTestCharlie / VC4 400h•10/9/24, 2:25 AM

ok, did the beacon reset, started running a single layer test, with holes in it. And my flow rate was really off, I was at 0.975 from the orca chits, it became nice at 0.825. So that stopped the mess after a void.
Elegoo rapid petg, white, if it helps anyone

CrashTestCharlie / VC4 400h•10/9/24, 2:27 AM

I also haven't set any Z changes or baby steps. The default after the reset:

RatOS | BEACON: Nozzle expansion offset of 0.064687mm applied to T

RatOS | BEACON: Nozzle expansion offset of 0.064687mm applied to T

And I've left it. So far nice squish and the first layer is measuring correctly to the silicer height

DDapperDangus Wanted to jump here and be apart of this discussion. Hopefully I can help or she...

tg73OP•10/9/24, 4:55 AM

I possess a ti tube but it's not fitted because it was too twisted. I have since hopefully detwisted it and will try it when I receive my second VC4.

Are you saying that you are now able to print perfect unattended full first layers?

CCrashTestCharlie / VC4 400h ok, did the beacon reset, started running a single layer test, with holes in it....

tg73OP•10/9/24, 8:11 AM

Yeah, I also got my PETG extrusion multiplier dialled in to about 0.88. These sub-0.9 values are apparently normal (I asked).

CrashTestCharlie / VC4 400h•10/9/24, 8:15 AM

Yeah, it's crazy, but the uhf melt zone makes a lot of goo and it just runs out

azoroes•10/9/24, 8:28 AM

I got this problems for over a year now, using a Vcore 3.1 500 enclosed, support from rat was really bad so far so I'm hoping this thread will help. I measured the Z-Shift some time ago and its crazy! I attatched some pictures of my measures, hoping this will help

Ttg73 I possess a ti tube but it's not fitted because it was too twisted. I have since...

DapperDangus•10/9/24, 8:41 AM

Ah, that’s unfortunate… No go on a perfect full layer though. I could probably get sorta close to one if I babysat it but I would want a nozzle camera at that point.

I’ve taken a break from it for a bit but I think I had to gradually raise my z offset as the print moved from (500,0) to (0,500). Don’t think I had to drop it unless I went too high. It was also gradually giving me the finger through frosting look towards the edges hence why I figured the gantry began to droop more towards the center.

Since the beacon scans much faster than printing speed, I don’t know if it would pick up that sort of variation.

Ttg73 Yeah, I also got my PETG extrusion multiplier dialled in to about 0.88. These su...

DapperDangus•10/9/24, 8:42 AM

That’s good to hear cause I thought my values must have been wrong there as well.

DapperDangus•10/9/24, 8:42 AM

I think my PLA was at 0.86 or something.

CrashTestCharlie / VC4 400h•10/9/24, 8:44 AM

I'm starting to the best strategy for beacon is to not save the z offset and put an adjustment in your filament setting to get the right squish.

Aazoroes I got this problems for over a year now, using a Vcore 3.1 500 enclosed, support...

DapperDangus•10/9/24, 8:47 AM

Yeah my mesh adds another ~0.5mm from cold (starts at ~0.5mm) to 110C so over 1mm total difference between my max and min at that temperature. Hot tightening at 120C put me at ~0.2mm max/min difference at both 80C and 90C. I should have tested at 85C as that would theoretically give me as close to 0mm as possible.

DapperDangus•10/9/24, 8:49 AM

And yes I know 0.5mm is a bad start but I got my mesh below 0.2 while cold and that all went out the window after my first long (19hr) ASA print.

Aazoroes I got this problems for over a year now, using a Vcore 3.1 500 enclosed, support...

tg73OP•10/9/24, 9:13 AM

We for sure expect plenty of thermal movement during the initial heat soak - so of course all testing reported in this thread needs to declare what heat soak took place. At this point I'm quite confident that people are still seeing this particular first layer issue even after very very long heat soaking. @azoroes can you confirm that you're seeing the specific issue described in this post, and what probe you have seen it with on your VC3.1? Please be careful with your answer, as if you are seeing this specific issue with a non-beacon probe, that will be useful evidence to consider (and we don't want to be confused).

azoroes•10/9/24, 9:38 AM

Hi, so I'm trying to get this as good as possible, please apologize any grammatical errors as i'm not a native speaker. I am using a beacon Rev H, RatOS 2.1 (yes, the exactly same thing happened with V2.0) heat soaked the bed about half an hour and started printing a 450x450 square. I'll put pictures of it in the description, at the +0,2mm marks I manually changed the Z offset as it basically stopped printing at that point.

Aazoroes Hi, so I'm trying to get this as good as possible, please apologize any grammati...

DapperDangus•10/9/24, 10:45 AM

Man, I could have taken a picture of mine and it would look spot on like yours.

DapperDangus•10/9/24, 10:46 AM

Was not patient enough to do the whole thing tho lol

Aazoroes Hi, so I'm trying to get this as good as possible, please apologize any grammati...

tg73OP•10/9/24, 11:30 AM

Can you confirm what versions of RatOS and RatOS-configurator you are using?

azoroes•10/9/24, 12:21 PM

Not a 100% sure what I used back then as I'm always trying to keep it as up to date as possible but I think it was ratos 2.1 rc1
Maybe I got time to try it later again

Aazoroes Not a 100% sure what I used back then as I'm always trying to keep it as up to d...

tg73OP•10/9/24, 12:27 PM

Ah - so it's not recent. It would be great if you could try that with the current RC3. Ideally also run through beacon calibration from scratch after updating. I used to have to baby step every first layer and got results like your example. Now it seems good to start with on all prints, then goes weird after eg 20 mins on a large 1st layer. The recent changes leading to RC3 include a bunch of fixes related to beacon config getting reset or screwed up whenever a print started (check recent pinned in #ratos-development for details).

tg73OP•10/9/24, 12:28 PM

Up to date docs for beacon calibration: https://github.com/HelgeKeck/RatOS/blob/documentation_v2.1/site/docs/configuration/beacon_contact.md

GitHub

RatOS/site/docs/configuration/beacon_contact.md at documentation_v2...

The preconfigured Raspberry Pi image that makes it easy to run Klipper + Moonraker + Mainsail on your printer. - HelgeKeck/RatOS

tg73OP•10/9/24, 2:32 PM

Just tested: it happens with PLA on an unheated bed. I'll post more detail later.

sardonumsei•10/9/24, 3:16 PM

Fantastic. I hadn't tried PLA. We need to get some developers on this thread.

Mmmm1223334444•10/9/24, 3:57 PM

Has anyone tried to calibrate extruder rotation distance?