X1C Z Axis Calibration

Hi. The dimensional accuracy of the printer seems great in the x and y directions, however the z seems off.

With a 120mm tall print, it is 2 mm short, measuring in at 118mm.

Am I able to correct this?

Thanks.

Welcome to the community.

To answer your question though. Simple answer: You can’t. There is no adjustment for this.

Hi, and thanks!

I am astounded. Everything I plan to print is large and requires dimensional accuracy. Did I buy the wrong printer? I wonder if Bambu has another printer with better tolerances, or is this within expectations? I feel I was able to adjust this on my Ender 5, but not sure.

Unfortunately you’re not the first to draw comparisons between the ender which had this capability. The only thing that I can think of is if you are looking for dimensional accuracy, achieve that through the CAD design. In my case, I use a variable when designing for both X, Y and Z and for each filament I design a text cube in CAD and then print the test model. From there I make dimensional changes. But just be cautioned that this is a crude approach because if the model has any holes or hollow structures, you’ll have to calibrate for each case.

A great example of this was the use of brass threaded inserts vs just plain plastic and self-tapping screws. With brass inserts you get the benefit of a strong metal and it is very friendly and precise for repeated assembly/disassembly. However, the brass insert itself has between a 50-100% space penalty which if the screws where at the edge of the model, there likely wasn’t sufficient material to allow for the heated insert without compromising the wall structure.

So enter the combined problem of both dimension accuracy AND screw hole variations and you can drive yourself crazy. So in the end, my solution was to go for X-Y accuracy in the slicer, Z-accuracy in the vertical and for screw holes, I simply added modifiers making more walls and then using a slightly smaller hole opening then drilling or tapping the hole to precise dimension. Crazy? Yes, but what alternative do we have?

I think there is a setting that helps with that but its more of a workaround if you ask me:

image

Maybe I’m wrong because I haven’ seen Olias be wrong, am I misunderstanding? Maybe you omit it because its worthless to slap on a few more layers to meet the proper z height if youre going for dimensional accuracy.

What are you talking about? I am frequently wrong. Fortunately there are a lot of folks here who are smarter than I am. :wink: But seriously, I usually put a disclaimer somewhere in my posts that nobody should take anyone’s word at face value without verifying it on their own rig, that especially includes my words. :persevere:

One of my favorites quotes by Ronald Reagan during missile reduction talks with the Soviets was “Trust, but verify,” which comes from the Russian proverb “Doveryai, no proveryai.” :+1:

There is no z-axis adjustment.

I’ve never needed one, but the models I’ve measured were only off by about 0.1-0.3 mm over 100mm, which is plenty accurate enough for my purposes.
2.0 mm over 120 mm seems extreme.

You may be able to compensate by scaling the z-axis in Studio by 101.7%.

Check your x and y measurements also, the filament you are using may be shrinking in more than one direction.

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This is something I actually hadn’t considered - a small scale factor, that might just work out fine - I’ll run a tower test and see, thanks for the tip.

Thanks everyone, I really appreciate the thoughtful responses.

I’m very surprised by the 2mm over 120mm. Are you sure that this is caused by the printer or slicer?
Typically X and Y come out more or less too small due to shrinking of the filament. In z that shouldn’t be a problem, because the shrinking doesn’t accumulate over the height. this is because the layer below has already cooled down mostly when the next one is layed down. So any shrinking in z will be compensated by the next layer.

Anyway, 2mm is too much for shrinking as a reason. Maybe you can share a 3mf file so some here will check for faulty settings?

I am having a similar problem with my oldest P1S as well (Have 3). Printed a 7" object and was out by 0.35" was running the same print on another machine and was only out by 0.02".

Printed out some test cubes on all 3 machines and busted out the starrett micrometer and found that machine was way out compared to the others. 0.005mm/layer. The new machine I got reccently was out by only 0.0025/layer. and my other was out by around 0.002mm/layer.

So possibly a wear issue on my machines as the one that is out is around 3500hrs now.

Kinda having the same issue right now.

X1C ~1400hrs. Generally exclusively printing PAHT-CF. So theres some accelerated wear…

Nozzle has also been a Diamond nozzle for awhile.

I was doing a batch print for a model I made several months ago from exhausting inventory on it. As it was printing I noticed some serious issues with it. All filament has been recently dried out in a blast oven for 24 hours at 80c. So I dont think its wet filament or anything.

But I’ve been getting some crappier prints as of lately from X1C as well for other prints but it didn’t require high tolerances so issue was ignored/passable.

My model was supposed to be 68mm Tall, but it measured 66.5mm So a pretty big difference in Z Axis accuracy. the XY seems normal and within expectations for PAHTCF.

Printing on a DarkMoon G10 plate, and also redid the bed tramming as thought maybe that’d help.

My first layer still looks pretty squished, so I have a feeling the Z Axis Bed leveling is also off, printing with a 0.4mm nozzle @ .16mm heights.

I’ve had to add some pretty serious Elephant foot compensation in the slicer and Z Shrinkage compensation into the Filament settings to compensate, but its not ideal. Cross referenced some older inventory I had printed from the same machine, and it does look off. Not 100% sure whats going on. But I’m also thinking the Z steps are ‘off’ or theres slack between the Print Head and guide rods, a drifting Force probe, as well as slop from the brass rings on the Lead screws all contributing to a pretty bad Z axis accuracy.

Any recommendations to bringing this back to original spec would be great.

Have you contacted BambuLab Support? There clearly is something wrong.
One idea: The 3 Z-spindles are connected by a belt. Maybe the pulleys are loose? If thats the case, a quick test could be to grab one spindle and turn one of the others by hand.

I recieved a solution from Bambu to adjust Z steps / Z compensation

In the start G-Code you have to add the following

M290.2 Z(Value) M500

with Value being expected height/actual height.

So mine was expected height 20mm / Actual Height 19.9009 so a value of 1.00497967etc

I tested it out and it did compensate and brought my Z height of the test cube up to 20.0152

It will also work for X and Y as well using the same line of code but swap the axis from Z to the one requiring compensation.

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