Bed Level Calibration Issues - Different first layer heigths
 
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Simon
(@simon-16)
Estimable Member
Bed Level Calibration Issues - Different first layer heigths

Hello,

I've again some bed level issues.
Again, means, really never resolved, but with some new infos.
I've made different XYZ Calibrations and they went always well. Then, I've started noticing some strange behavious. Seems that the left side is different comparing to the right side in terms of Z heigth.

These are my support settings:


Y distance from min:
------------------------------
Left: 10.62mm
Right: 10.60mm

Measured skew: 0.03°
------------------------------
Slight skew: 0.12°
Severe skew: 0.25°

[0;0] pint offset
------------------------------
X -0.55mm
Y 0.12mm

BTW the following are two pictures made with a macro lens on a Print Skirt that was covering the whole distance left-right.

[attachment=0]IMG_5980[1].JPG[/attachment]

[attachment=1]IMG_5979[1].JPG[/attachment]

You can notice the first layer is squashed on the right side, and ok on the left side 🙁

What causes this to the print?
Well, if the Z height is correct on the right side, on the left side the objects are not attached well on the printing plane. It happens they detach and... you know what happens...
If the Z hieght is correct on the left side, on the right side the first layer is too much close on the printing plate and squashed, causing on the first layer full flat surfaces, some little blobs. Growing on the layer the XY movements sometimes causes skratches if Z hops are disabled.

I've made my last XYZ Calibration on a Prusa 3.1.2 firmware. Yesterday I've updated on firmware 3.2.1. No recalibration was asked.
Before I try (again) a new XYZ Calibration with the new firmware (even if it helps), what can I do?

Thanks a lot!

Simon

Posted : 28/05/2018 9:45 am
Gato
 Gato
(@gato)
Reputable Member
Re: Bed Level Calibration Issues - Different first layer heigths

To see how leveled your bed is you can use this great Octoprint plugin https://shop.prusa3d.com/forum/user-mods-octoprint-enclosures-nozzles--f65/-help-needed-octoprint-prushmeshmap-plugin-t15333.html . In that thread you will find how to make physical adjustments to the bed and visualize effect of changes. Once physical changes were done, and if you still need to improve bed leveling then you can use Calibration -> Bed Level correction from the LCD.

Posted : 28/05/2018 5:31 pm
Simon
(@simon-16)
Estimable Member
Topic starter answered:
Re: Bed Level Calibration Issues - Different first layer heigths


To see how leveled your bed is you can use this great Octoprint plugin https://shop.prusa3d.com/forum/user-mods-octoprint-enclosures-nozzles--f65/-help-needed-octoprint-prushmeshmap-plugin-t15333.html . In that thread you will find how to make physical adjustments to the bed and visualize effect of changes. Once physical changes were done, and if you still need to improve bed leveling then you can use Calibration -> Bed Level correction from the LCD.

Thank you!
I'll look into your suggestions and let you know!

Simon

Posted : 28/05/2018 5:37 pm
Simon
(@simon-16)
Estimable Member
Topic starter answered:
Re: Bed Level Calibration Issues - Different first layer heigths

Great link.
I'm working on it, not easly, but I'm getting some interesting results.
Thanks!

BTW, simple-stupid question. Does not the Initial calibration compensate/correct even these bed differences between side right/left?

Posted : 29/05/2018 2:55 pm
Gato
 Gato
(@gato)
Reputable Member
Re: Bed Level Calibration Issues - Different first layer heigths

Good question. As far as I know/understand, the initial calibrations do: align z as it goes all the way to the top, finds the circles in the bed to know where things are in x,y and uses Pinda sensor to know where is in z and not hit bed and have an accurate z location. It then does 9 point calibration before each print to confirm that bed remains the way it was within error. It also manages to calculate of axes are perpendicular.

Warping of bed, as I understand it, will have an impact in the shape of what gets printed. It’s physics. Software might compensate and be able to print straight lines but one side of the printed object will be taller than the other side if things are not leveled. Of course this is so small that you might not notice/care.

I’m relatively new to this so might be wrong.

Posted : 29/05/2018 4:53 pm
Simon
(@simon-16)
Estimable Member
Topic starter answered:
Re: Bed Level Calibration Issues - Different first layer heigths

Hello,

It makes sense. Thanks anyway for your answer. 🙂

Simon

Posted : 29/05/2018 4:57 pm
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