Yet more first layer fails  

RE: Yet more first layer fails

Z height too close to bed?

RE: Yet more first layer fails

Back-left is too far off and front-right is overly squished. So it seems like you've got quite a skew going.

First thing I'd try is putting Z to zero then manually raising it until you hit both stops - leveling both sides. LCD to lower the bed a little then running Z-calibration.

Also double/triple check that you didn't install the leadscrew motors in opposite/wrong sides and that all the bed screws are good to go.

You could also look into making sure the z-stops/leadscrew cap things are correct. I think there's been at least one other post of having outdated z-caps and they printed/installed new ones from Prusa's updated XL CAD files which fixed things for them, but I dont remember what their issue was.

Maybe even recheck how square your printer frame is? Maybe the preassembled top frame is slightly off of the rest of the back-left frame?

Mine for comparison. Defaults of 0.2 SPEED print settings on default 5T IS 0.6 nozzle printer.

RE:

One thing i noticed on my machine:

With the standard preset, the printer heats the nozzle to 170 deg C before printing. This leads to oozing out filament while probing. I get a lot of little marks on the print bed. I saw a little spot on one of the non printed squares on your image aswell. So if you also have this problem, this might be the root cause:

If there is filament leaking while probin the bed, the z offset is just off by some small amount.

I lowered the preheat temperature in my start gcode from 170 to 140. Now geeting really nice first layers without any filament oozing while probing
 

(i'm of course using a frech role of prusament pla)

In your printer settings, got to custom G-Code and search for the line:

`(first_layer_temperature[initial_tool] - 25) : (filament_type[initial_tool] == "FLEX") ? 210 : (filament_type[initial_tool]=~/.*PET.*/) ? 175 : 170)} ; wait for temp`

change the 170 to 140

`(first_layer_temperature[initial_tool] - 25) : (filament_type[initial_tool] == "FLEX") ? 210 : (filament_type[initial_tool]=~/.*PET.*/) ? 175 : 140)} ; wait for temp`

and try again

(preheat temp is shown on printers display while probing, make sure changes actually take effect)

(also, @prusa, why is this not the default? are you actually using your machines yourself? i can't imagine this happend not to you.. other users on the internet reporting same behaviour)

RE: Yet more first layer fails

Posted by: @baconfase

Back-left is too far off and front-right is overly squished. So it seems like you've got quite a skew going.

First thing I'd try is putting Z to zero then manually raising it until you hit both stops - leveling both sides. LCD to lower the bed a little then running Z-calibration.

Also double/triple check that you didn't install the leadscrew motors in opposite/wrong sides and that all the bed screws are good to go.

You could also look into making sure the z-stops/leadscrew cap things are correct. I think there's been at least one other post of having outdated z-caps and they printed/installed new ones from Prusa's updated XL CAD files which fixed things for them, but I dont remember what their issue was.

 

Maybe even recheck how square your printer frame is? Maybe the preassembled top frame is slightly off of the rest of the back-left frame?

  

Appreciate the feedback.  Mine was "fully assembled" so all I really did was to install the docks.  Even this was not problem free however, as the alignment for dock #5 feels off.  The tool makes a much louder noise when docking/undocking.  Swapping docks from another spot to 5 does not move the problem, so it is something specific to that dock postion.  That makes me wonder about frame squareness.  I'll get out my machinists' square and check it today.

As to z leveling, I'll try what you said.  I have done several z calibrations, but that apparently didn't do the trick.  It does raise the bed high enough to create a buzzing sound, which I am assuming is the bed hitting the stops.

Regarding bed screws, is it just a matter of checking that they are all tight? Is there a specific torque I should tighten them to?

Many thanks for the help so far!

RE: Yet more first layer fails

Thanks for your feedback.  I did mod my printer to have the small brass Dremel brushes in front of the dock to wipe the nozzles, but you are right there is still some oozing happening.  Lowering the temp is a great idea.  I'll try that right now.

Posted by: @torbenberger

One thing i noticed on my machine:

With the standard preset, the printer heats the nozzle to 170 deg C before printing. This leads to oozing out filament while probing. I get a lot of little marks on the print bed. I saw a little spot on one of the non printed squares on your image aswell. So if you also have this problem, this might be the root cause:

If there is filament leaking while probin the bed, the z offset is just off by some small amount.

I lowered the preheat temperature in my start gcode from 170 to 140. Now geeting really nice first layers without any filament oozing while probing
 

(i'm of course using a frech role of prusament pla)

In your printer settings, got to custom G-Code and search for the line:

`(first_layer_temperature[initial_tool] - 25) : (filament_type[initial_tool] == "FLEX") ? 210 : (filament_type[initial_tool]=~/.*PET.*/) ? 175 : 170)} ; wait for temp`

change the 170 to 140

`(first_layer_temperature[initial_tool] - 25) : (filament_type[initial_tool] == "FLEX") ? 210 : (filament_type[initial_tool]=~/.*PET.*/) ? 175 : 140)} ; wait for temp`

and try again

(preheat temp is shown on printers display while probing, make sure changes actually take effect)

(also, @prusa, why is this not the default? are you actually using your machines yourself? i can't imagine this happend not to you.. other users on the internet reporting same behaviour)

RE:

Posted by: @torbenberger

One thing i noticed on my machine:

With the standard preset, the printer heats the nozzle to 170 deg C before printing. This leads to oozing out filament while probing. I get a lot of little marks on the print bed. I saw a little spot on one of the non printed squares on your image aswell. So if you also have this problem, this might be the root cause:

(also, @prusa, why is this not the default? are you actually using your machines yourself? i can't imagine this happend not to you.. other users on the internet reporting same behaviour)

Let me just say, sir, that you are a gosh darn genius!!!!  That one change made a massive improvement in quality.  It's still not 100% level, but it seems that if I do your trick combined with the 10 minute heat soak at 80℃, that gets me a 95% perfect layer.  It also keeps from getting blobs of goo at every probing point.  I am shocked that the default Prusa printer profile has the nozzle heat up so hot.  This is my first 3d Printer, so I didn't think that was abnormal but after your comments, I do have to wonder how much they really used/tested this printer.

Now, I still want to investigate further, because once I do the 140℃ probing, I would expect mesh bed leveling to correct for any bed issues, so it sounds like there may still be some mechanical issues to deal with.  The heat-soaking may just be working around those issues.  I'm going to follow some of @BaconFase's suggestions tonight and check the mechanical setup.

RE: Yet more first layer fails

I‘m also kinda shocked what the default settings lead to.. also opened another thread here which points out some things that might lead to damage to the printer. Really sad to feel like a beta tester for a printer that’s that expensive and has been in development for so long. My mk3s+ worked flawless from first print on, and even my first prusa in 2013 had less bugs 😀

prusa: you might have some „B level guys“ in your development team and probably should swap them out.. just sayin.. 

but glad the trick helped 🙂 

RE: Yet more first layer fails

Regarding bed screws, is it just a matter of checking that they are all tight? Is there a specific torque I should tighten them to?

Basically yea. They don't give a torque number so goodntight relative to screw size i guess.

There are also 4 screws on the underside of each of the heating elements. If one of those heating pads are slightly proud that could unlevel things.

Mine was "fully assembled"

There have been a couple posts about bent beds on fully assembled units due to how they packaged things, you might want to look those up.

Glad Torben's suggestion helped, I'm basically shooting in the dark.

RE: Yet more first layer fails

I just realized a mod renamed this thread - this was not the original name.  That's concerning.  It was called Yet more "perfect first layer" fails.