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AgentNoise
(@agentnoise)
Eminent Member
Nozzle too high when printing

The nozzle is too high when printing but is fine when running the first layer calibration.  The z offset is set to 0.850 and prints great on the first layer calibration.  It's barely connecting to the bed when I run a print job. Using OctoPrint and sending the gcode straight from PrusaSlicer.  I have confirmed the z offset is stored by checking it from the LCD. Any ideas?

Posted : 11/07/2019 4:41 pm
AgentNoise
(@agentnoise)
Eminent Member
Topic starter answered:
RE: Nozzle too high when printing

I've tried increasing the mesh bed level to 7x7 but it did not help

Posted : 11/07/2019 11:47 pm
Peter M
(@peter-m)
Noble Member
RE: Nozzle too high when printing

Print from sd card to test if it is octoprint.

 

move z axis to top, left and wright should hit at the same time.

Oil all rods. Maintenance, tighten all bolts on the printer.

do z calibration,

then do first layer calibration.

Test again

Posted : 12/07/2019 9:47 am
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(@)
Illustrious Member
RE: Nozzle too high when printing

You might want to check your print profiles. Ensure in Print Settings layer one is set to 0.20, and not something odd; also, check the Printer Settings Z-offset value is also 0.

Posted : 12/07/2019 10:25 am
AgentNoise
(@agentnoise)
Eminent Member
Topic starter answered:
RE: Nozzle too high when printing

I don't think it's a layer setting.  After more testing it's doing it on first layer calibration too.  So if I get it set and prints ok then immediately run another first layer calibration it's too high again. I ran a Z calibration again, still doing it. When I am off work I'll test lowering the Pinda probe and see if that helps

Posted : 12/07/2019 1:20 pm
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(@)
Illustrious Member
RE: Nozzle too high when printing

Have you done the initial first layer calibration from the menus?  The one that makes the zig zag on the bed?  There's a rumor the firmware ignores your attempts to use Live-Z if you haven't first ran the internal cal.

Do that, let it complete (make a few changes as it goes to let it think you are setting a value); then do a real Live-Z adjust using a fair sized part so you have time to adjust.

Once those two steps are done, the nozzle should be pretty close on subsequent runs; though there is temp sensitivity in the PINDA that will cause a run to run difference, but generally the first layers are still usable.

If you are seeing layer 2 being too high, that's a totally different issue and one that doesn't have any sensible easy fix.  If the LCD shows the layer height of L1 at 0.2 mm and then layer 2 at 0.35 yet the nozzle is really 2mm higher and printing in air... that's a broken something. 

 

This post was modified 3 years ago 2 times by --
Posted : 12/07/2019 9:32 pm
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(@)
Illustrious Member
RE: Nozzle too high when printing

I also just went through a weird experience: gcode that doesn't have the G80 mesh level does some pretty weird stuff. First pass I added -0.600 mm (-0.675 to -1.275), almost looked like it'd work. Second pass added another -0.500 mm and still hadn't touched down (-1.775), so I gave up.

It really should work, but something is definitely broken in 3.7.1 firmware.  Also found the bed level correction is essentially not working, too.  Seems the FW is using an absolute value rather than indicated sign.

Go back and ensure your printer profile has the G80 mesh level command.

Posted : 13/07/2019 6:55 am
AgentNoise
(@agentnoise)
Eminent Member
Topic starter answered:
RE: Nozzle too high when printing

So, I am using the default prusaslicer profile.  The GCode does have G80 at the begging.  The firmware is 3.7.2.  The live z adjust I am doing is always through the first layer calibration.

It's doing it any time you run a print. SO if I run a first layer calibration from the lcd, get it correct and then immediately run it again, it's too high.

This post was modified 3 years ago by AgentNoise
Posted : 14/07/2019 2:32 am
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(@)
Illustrious Member
RE: Nozzle too high when printing

The MK3 is prone to losing it's brain at times.  If you print a test print (e.g., a 100 mm cal circle) and during that print adjust Live-Z and exit back to the top menu; and then run that same print again, and Live-Z is the same value yet the printer is printing higher; AND the PINDA screw is tight; I'd vote that the printer isn't working properly and there is a chance the EEPROM data is corrupt.

Performing a Factory Reset with full data clear is the next thing to try.  You'll be dropped at the kit build Power Up Wizard and will have to run all of the initial setups: self test, Z cal, XYZ cal, etc.  And then drop in PID cal and Temp cal, and any linearity corrections you've applied.

 

But --- have you tried printing one of the sample gcodes from an SD card, just as a sanity check?

This post was modified 3 years ago by --
Posted : 14/07/2019 2:49 am
AgentNoise
(@agentnoise)
Eminent Member
Topic starter answered:
RE: Nozzle too high when printing

I think I figured it out.  For some reason the Flow under Tune was set to 90%.  Even after I did a factory reset and then calibrated again it was still too high. What looked like lines that were from a nozzle too high were actually under extruded.  I'm used to under extrusion being inconsistent, not perfectly uniform, that's what threw me through a loop. 

Getting through a print now.  I'll mark this as answered if it all works out

Posted : 14/07/2019 3:40 pm
AgentNoise
(@agentnoise)
Eminent Member
Topic starter answered:
RE: Nozzle too high when printing

Well I printed the Prusa tag from the SD card and it's better but still not right. I used to get perfect first layers that had a smooth, glass like finish now I can feel the individual lines on the first layer.  Without glue PLA wont even stick to the bed

Posted : 14/07/2019 4:04 pm
Peter M
(@peter-m)
Noble Member
RE: Nozzle too high when printing

If not sticking, clean the bed with dish soap, and try again.

See also the forum a lot of users have this problem, not good cleaning.

Posted : 14/07/2019 5:27 pm
Dave Avery
(@dave-avery)
Honorable Member
RE: Nozzle too high when printing

sounds like live Z is too high.   use the life-adjust-z-my-way procedure to set your live Z

Posted : 14/07/2019 5:30 pm
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(@)
Illustrious Member
RE: Nozzle too high when printing

Without glue PLA wont even stick to the bed

If glustik is helping, your bed is definitely dirty.  Soap and water wash, use clean paper towels only to wash then dry the sheet.  Handle only by the edges, and never touch the sheet surface with bare fingers.   Don't use alcohol as a primary bed clean, it generally leaves a microscopic film of whatever you are cleaning off - if oil, it's great for printing PETG and keeping it from sticking too hard, but lousy for PLA.

A dirty bed will also manifest as under-extrusion and excess nozzle height since the PLA tends to bead like water on wax. 

Flow under Tune was set to 90%

If you completed a factory reset with a data clear, the flow rate is reset to the factory 100%.  If it was still 90% after the reset, then good chance you did not do the data clear part of the exercise (requires a different menu selection).   That, or your gcode has a command to set flow to 90%.

Posted : 14/07/2019 6:37 pm
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