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Frank
(@frank-8)
Trusted Member
First layer calibration issue

I've been printing successfully with my MK3S for some time now, but I am having difficulty getting the first layer calibration dialed in properly after a calibration reset.  I went through the entire 'preflight' process again, and everything seems to be going well, except the first layer calibration.  It seems I can get the layer height adjusted properly for left-to-right or right-to-left, but not both simultaneously.  It looks for all the world like the nozzle is asymmetric, but I have no idea how that would happen, and AFAICT visually, it looks OK.  I have attached a photo or two to illustrate the problem.  

Any thoughts?

TIA,

Frank

 

Attachment removed
Posted : 05/02/2020 2:45 am
bobstro
(@bobstro)
Illustrious Member
RE: First layer calibration issue

The gouge down the center of the extrusion indicates your nozzle is way too low. Raise it up a bit (I'd go up 0.6mm) to make sure you're way on the high side, then work down.

If you have not already done so, try using Jeff Jordan's "Life Adjust" procedure for calibrating your Live-Z setting. It is much easier to use and understand than the on-board routine. It's much easier to make mid-print adjustments accurately with. In general, start high (less negative) and work lower (more negative) in large increments (e.g. 0.1mm) until the filament starts to stick on its own. When you've got your Live-Z setting adjusted properly, you should be able to gently rub the extruded lines on the PEI surface without dislodging them.  Then start lowering (more negative) the level until there are no gaps between layers. 
My notes and disclaimers on 3D printing

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 : 05/02/2020 5:03 am
Frank
(@frank-8)
Trusted Member
Topic starter answered:
RE: First layer calibration issue

Your post seemed to focus on the left-to-right appearance, while ignoring the right-to-left appearance.   

I've had my MK3S for several years now and am quite familiar with first layer calibration and using 'Live Z' to get the first layer correct. However, I've never run across the situation where the layer appearance in one direction is so markedly different than the layer appearance in the other.  If I adjust the Z-offset to get the left-to-right pass to look 'right', then the right-to-left pass doesn't attach to the print bed at all.  The picture I provided is the best compromise I could obtain using the 'live Z' feature.

Do you have a theory why they are so different?

Posted : 05/02/2020 1:45 pm
Jimbo70
(@jimbo70)
Estimable Member
RE: First layer calibration issue

I think your X-axis carriage or your nozzle is loose. Grab you cold nozzle and see if will wiggle, if it does you need to tighten some bolts.

Posted : 05/02/2020 2:19 pm
bobstro
(@bobstro)
Illustrious Member
RE: First layer calibration issue
Posted by: @frank-p8

Your post seemed to focus on the left-to-right appearance, while ignoring the right-to-left appearance.   

I see that, but I'm not sure it's significant. Getting a good 1st layer would help determine if that's an issue in practice, or only when the nozzle is too low. I'm operating under the assumption that if the nozzle is so low as to gouge the filament in any direction, it's too low. Fix that, then adjust for other issues.

My notes and disclaimers on 3D printing

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 : 05/02/2020 3:57 pm
Frank
(@frank-8)
Trusted Member
Topic starter answered:
RE: First layer calibration issue

@louis-j

Thanks for the idea.  I checked the nozzle, and it seems secure in the heat block, and the extruder assembly doesn't exhibit any obvious looseness.  Any other ideas?

 

Frank

 

Posted : 05/02/2020 9:18 pm
Jimbo70
(@jimbo70)
Estimable Member
RE: First layer calibration issue

@frank-p8

What I see looks like an pencil angled on a paper, in one direction the pencil is dragging and the opposite direction it is pushing and shuddering and in the 90 degree direction it makes no difference. The angle would not need to be great to cause this appearance.

Maybe you could try to loosen and retighten everything in the extruder assembly that is connected directly or indirectly to the X axis rods.

All if this is just part of the JOY of 3D printing - the challenges never end, and the JOY never ceases.

Posted : 06/02/2020 1:12 pm
Frank
(@frank-8)
Trusted Member
Topic starter answered:
RE: First layer calibration issue
Posted by: @frank-p8

@louis-j

Thanks for the idea.  I checked the nozzle, and it seems secure in the heat block, and the extruder assembly doesn't exhibit any obvious looseness.  Any other ideas?

 

Frank

 

It looks like the problem was due to a worn nozzle.  When examined under magnification, it appears that I must have run it into the print bed at one point or another, and it developed an angled face. In one direction, the face was slanted away from the filament bead flow and so allowed free and unfettered flow, but in the other direction it was slanted down toward the print bed and the filament had to squeeze under the gap, causing the 'shovel' effect.  A new nozzle seems to have eliminated the problem.

Frank

 

Posted : 09/02/2020 1:30 am
rmm200
(@rmm200)
Noble Member
RE: First layer calibration issue

Certainly one of the cheaper, easier solutions.

Just make sure you followed installation instruction. The hex part of the nozzle should not touch the hot end.

Posted : 09/02/2020 1:56 am
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