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First layer hight issue  

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Lups
 Lups
(@lups)
Eminent Member
First layer hight issue

Hi,

i just finished my upgrade to the mk3s. All good so far but when I do the first Layer high calibration the layer is different depending on the location of the printhead. I don't change the Z setting. When it's in the back the nosle is too high when it goes to the middle it's way to low and the line is very thick and thin. How can that be, the printer does the 9 point test before without error so it should be calibrated.

Thanks

Posted : 16/04/2019 3:33 pm
Endymion
(@endymion-2)
Active Member
Re: First layer hight issue

I have a similar issue. See the picture. The corners look good but bad in the center area. Suggestions appreciated!

Posted : 17/04/2019 4:10 am
Endymion
(@endymion-2)
Active Member
Re: First layer hight issue

Think I see what is going on with my situation. The bed is bowed significantly down in the center. See the attached pictures. I assume that the amount of bowing is larger than the 9 point calibration can correct for so get the result I showed earlier.

Posted : 17/04/2019 4:33 am
bobstro
(@bobstro)
Illustrious Member
Re: First layer hight issue


Think I see what is going on with my situation. The bed is bowed significantly down in the center. See the attached pictures. I assume that the amount of bowing is larger than the 9 point calibration can correct for so get the result I showed earlier.
Log into the online store and chat with Support. They're pretty good at shipping out replacements for defective parts.

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and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 17/04/2019 5:15 am
Neophyl
(@neophyl)
Illustrious Member
Re: First layer hight issue

One change I did when I built my mk3 was I put some stiff small o-rings between the bed carriage and the standoffs (away from the build plate so heat wouldn't be a problem). This has allowed we to adjust the bed level slightly by selectively tightening the screws as it compresses the o-ring under it. Not by a lot but enough. I've lost about 2mm of height from the Z axis but was worth it to me for the ability to tweak the bed.

Posted : 17/04/2019 12:11 pm
Lups
 Lups
(@lups)
Eminent Member
Topic starter answered:
Re: First layer hight issue

I checked this as well but I don't have those gaps. It's all flat.

Posted : 17/04/2019 1:36 pm
vintagepc
(@vintagepc)
Member
Re: First layer hight issue

Install the 3.7 firmware and change the mesh bed setting to 7x7. It should help significantly.

Posted : 17/04/2019 1:45 pm
Lups
 Lups
(@lups)
Eminent Member
Topic starter answered:
Re: First layer hight issue


Install the 3.7 firmware and change the mesh bed setting to 7x7. It should help significantly.

Ok will try it now.

Posted : 17/04/2019 4:05 pm
Mustrum Ridcully
(@mustrum-ridcully-2)
Honorable Member
Re: First layer hight issue

measure the height of the bed spacers one of mine was .5mm shorter than the longest one if you have a similar difference in your spacers and you put the short one in the middle your bed would look like that. I lapped the spacers to all be the same height by using 400 wet or dry paper on my flat stone countertop till they all were the same length as the shortest one. the 7 x 7 leveling in the newer firmware might deal with the variation in your photo but I like mechanical fixes before I resort to software or firmware fixes

Posted : 17/04/2019 10:22 pm
Endymion
(@endymion-2)
Active Member
Re: First layer hight issue

Support suggested upgrading to the latest FW which has a 7x7 bed leveling mode. The 7x7 mode helps but not perfectly. I think I will try the nylock nut leveling approach next. https://github.com/PrusaOwners/prusaowners/wiki/Bed_Leveling_without_Wave_Springs

Posted : 18/04/2019 7:46 am
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