Sounds like we need a new theory. 
What Do you mean? What theory?
Has anyone found an improvement regarding this issue?
I tried everything that came to my mind, but I am out of ideas now.
The only thing that helped to improve accuracy a little was the “belt tightening” method.
Anyway an 100mm L-shaped object is still constant off -0,1mm on one axis and 0,2mm on the other.
This thread echoes other Bambu Lab specific forums, being reddit, FB etc. The general tone of responses seem to be an attack on an OP for asking a question or proposes anything but perfection from one of these machines. Followed by a slew of upvotes/likes for non-helpful comments. The OP is simply pointing out a performance issue with his machine. On a support forum. He’s not asking how you feel about his question. He appears to be looking for a solution.
This seems to be an unfortunate trend for Bambu. I’m not going to analyze why but I haven’t seen this in forums for machines that don’t market a plug-n-play solution.
Instead of trying to prove the OP wrong the right approach could be a non-emotional “That’s an interesting find. Thanks for sharing your findings. I don’t know why this is happening. Let’s look into this and figure it out.”
That being said I’ll be following this thread as I’d like to see a method to calibrate / control these tolerances in an measurable and repeatable way. I do understand Bambu’s hesitance to open up too much control as it complicates their ability provide support. And self-calibration is one of their selling points. Perhaps they can add this as a option which can be switched on and off for their troubleshooting purposes. I’ve always been anal and thorough, measuring steps-per-unit then adjusting these numbers when building a Marlin firmware. My Mono-price, Enders, Cr-10s have been accurate and repeatable.
TL;DR: It’s not up to us to decide if OP needs to calibrate to his acceptable tolerances.
8 Likes
I suppose you’re right: 95 posts, and nothing got solved, did it?
Hi together,
I just stumbled over this video here: (YouTube)
Within the video the creator explains how the belts are slightly missaligned and how on his printer also the squareness between the reference-points is off.
And how to fix it.
As CoreXY systems are pretty picky when it comes to belt tension and alignment I could imagine that this is a possible solution to get at least some of the issues sorted out. (Espacially my issue with different deviation in X and Y axis).
I will give this a shot in the next couple of days.
If someone finds the time to try it earlier: please share the results.
BR
/Kevin
All well put. I wish i could have said it this well.
@adminmat Also a perfect statement. This is why i barely ever post anymore.
2 Likes
The carbon rods are only specced to ±0.1mm for straightness and the bushings have almost half of that too in running clearance, you’re not going to get much closer than that without getting very lucky with the tolerance stack up on the carbon rod/bush motion system, unfortunately. It’s why you’re always going to have different deviation in the Y vs X axis.
1 Like
I tried this because I don’t like the ripples when printing petg. Diagonally, the printer had a difference of 2 mm. I compared everything using calibrated gauges. No result. Only now the waves are cleaner. It seems that some inaccuracy and curling is probably a standard feature.
1 Like
I’ve found that compensation for shrinkage by entering a calculated shrinkage factor into the material profile is pretty much the silver bullet for my accuracy problems. I believe only Orca supports this though.
I use a model and spreadsheet from Thingiverse to calculate it for each filament:
https://www.thingiverse.com/thing:1982686
And also make sure to zero out the values in X-Y hole compensation and X-Y contour compensation before running the print.
Here’s some of them:
Inland PLA-CF Black: 99.638%
Hello 3d Silk Gold PLA: 101.131%
eSun ABS+ Black: 99.118%
Inland ABS Black: 100.762%
3 Likes
The Ultimaker-cura slicer can figure the compensations automatically. It’s free and supports 3d printers from a lot of different manufacturers, but, unfortunately, bambu labs printers aren’t among them, at least not yet.
So, in an effort to find a solution, I reached out to support with all my measurements that I posted above along with the analysis of the situation. It took a really long time - 24 days - to get a reply, and here it is:
Hello,
Thank you for contacting Bambu Lab support. I am sorry to see that you are experiencing problems with your printer, but rest assured we will provide support to solve them as soon as possible. In this case, the problem seems to be related to the print quality.
To address this issue further, can you please start by performing a bed leveling and belt tensioning procedure? Then print some calibration cubes and compare the tolerances.
Additionally, once complete, leave the printer idle for 10 minutes or so before exporting the print logs for further review.
Belt tensioning: Belt tensioning guide Bed leveling: Bed leveling guide Log upload: Log upload instructions
Please let me know if you have any questions or concerns.
Best Regards, Miles Bambu Labs Support
In good faith, I’m going to do all the steps that they have asked, and then I will take my measurements again and respond. I’ll update this thread with both my results and their response once I receive it. I’m expecting them to take another three weeks once I’ve replied, but we’ll see.
2 Likes
@PEZ3D interesting issue.
I regard that the printer “setup” is focused on aesthetics, which, from what I read from experts, conflicts with tight accuracy or tolerances.
I value accuracy and tolerance more than good looks, as I use the printer primarily for functional prints.
I can say that with a 0.4mm nozzle, I never notice.
Yet, after the typical flow rate calibration procedure for each filament spool, I start a fine-tuning procedure using tolerance tests until I get a 0.05mm fitting.
Also, I set my outer wall print speed to 60 mm/s when tolerance is critical. With a 0.6mm, I had some difficulties getting accurate dimensions in the three axes; it seems to have improved in the last months, maybe by software and firmware updates.
Yet, after reading about others’ experiences, I need to recheck to be sure I am still achieving such an outcome.
I read about a similar issue months ago; in that case, the BL support team solved the issue by providing accurate instructions to fine adjust the belt tension. If I find it, I will share it.
@RPMiller, I look forward to knowing more about BL support solutions for your trouble ticket.
For fixing skew on printers like the X1, CNCKitchen gives a couple workaround options until there’s a more permanent solution:
TL;DR: octoprint or g-code post processing
I don’t see any instructions related to X1C. Just a quick mention of the Prusa. Did I miss it?
back it up a few seconds. He says if you can’t change your firmware like on the new bambu machines or the prusas…
Right, but now instructions of what to actually do.
Hello,
new here, running Mk3 for some time and recently X1C carbon. On X1C also having troubles with dimensional accuracy, tracked it down to skew:
- Califlower calibration test show => skew -0,19° (pretty bad for my needs)
Based on good discussion in this thread I see 3 possible skew remedies:
- manually distort print model (step) to compensate for printer skew prior slicing – not easy, not convenient, but seems feasible
- Boneyard labs video recommend to shim-out the x/y skew – based on my tests, this seems to work in short term. But I actually don’t fully understand the core XY kinematics & belt system and I am a bit concerned this may cause some undesired effect/belt tension/wear in long term?
- CNC kitchen Stefan’s video seems to indicate GoSkew G-code postprocessor - I don’t have any experience with such technique and was not able to find any reference/discussion anybody using it for Bambu or Orcaslicer
Does anybody here have relevant experience to share which of the solutions actually work and is most reliable/robust/convenient in long term please?
1 Like
Belt tension comes to mind as a 4th point. But you have probably already done that.
Goskew gives directions on what to do and how to do it: