First Layer Calibration issues - cannot move nozzle down  

RE: First Layer Calibration issues - cannot move nozzle down

Hi, I would say you don't appear to have gone low enough

I just replied to a mini user at the following link  could you please look at that thread... 
https://forum.prusa3d.com/forum/how-do-i-print-this-printing-help/newbie-advice-on-debugging-mini-sag-issue/#post-601789

most of the information about first layer adjustment and surface cleaning apply to the mk3vaw well. 

mk3 test files are available in the thread linked below, at the bottom of the first post!
https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/

have you tried 7x7 mesh bed levelling?  available through the LCD menu. 
it tests 49 points, instead of the normal 9 points. I find it works better for me

regards Joan

RE: First Layer Calibration issues - cannot move nozzle down

Thanks Joan for the reply - and the link to the other post, but this doesn't seem to address my issue that during the calibration, moving the knob counterclockwise doesn't seem to move the nozzle closer to the bed which, as you pointed out is the primary issue. I'm so far off right now that mesh bed leveling would even matter...

RE: First Layer Calibration issues - cannot move nozzle down

is your live Z at -2.000 mm or larger? or is it still around the -0.760 as shown on the video? 

Last time I noted My Live Z it was greater than 1.000 as can be seen below

you still many not be low enough
regards Joan

P.s. the numbers above are unique to my printer. yours are likely to be different

RE: First Layer Calibration issues - cannot move nozzle down

Hi Joan, I am not sure what you mean by "Live Z"?  Are you referring to the distance between the nozzle and the bed when printing during 1st layer calibration? If so, I can only approximate that visually...

RE:

 when you are doing the first layer configuration, and twiddling the LCD Control, you are adjusting the 'Z' height, and you are able to adjust it whilst the printer is printing live...   so it is called Live 'Z' Adjustment

On your Mk3 series Printer, you have either a Pinda, or Supa Pinda (depending on the model of printer). 
During initial configuration, the nozzle is manually adjusted until it just touches the build plate, then the Pinda /Supa Pinda is adjusted to be approximately a 'Zip tie' thickness, above the buildplate. 
when the printer initilises at the beginning of a print, it tests the relationship between the Pinda end, and the build plate and this should always result in the nozzle being close to the build plate, but a 'safe' distance above the build plate, 

Then you move on to First layer configuration... 
As you have found, the Prusa First layer configuration tool is a little difficult to use. 
I find the 'Life Adjust 'Z' My Way' technique to be much easier to use.  Live Z only goes into negative values and this negative value, is the distance that the nozzle is lowered from the Pinda Sense point. 

I believe Prusa are happy with Live 'Z' values between 0.000mm and -2.000mm
If the extruder is still too high, when the live Z value is approaching -2.000mm it is best to reset  live Z to 0.00, readjust the Pinda slightly higher. then re adjust the Live Z. until you get a nice 'Squish'. 

It seems difficult at first, but gets easier with experience. 

regards Joan

RE: First Layer Calibration issues - cannot move nozzle down

Hi Joan, thanks for getting back to me:

when you are doing the first layer configuration, and twiddling the LCD Control, you are adjusting the 'Z' height, and you are able to adjust it whilst the printer is printing live...   so it is called Live 'Z' Adjustment

Okay - understand what you mean by that now

On your Mk3 series Printer, you have either a Pinda, or Supa Pinda (depending on the model of printer). During initial configuration, the nozzle is manually adjusted until it just touches the build plate, then the Pinda /Supa Pinda is adjusted to be approximately a 'Zip tie' thickness, above the buildplate. when the printer initilises at the beginning of a print, it tests the relationship between the Pinda end, and the build plate and this should always result in the nozzle being close to the build plate, but a 'safe' distance above the build plate, 

I have a super-Pinda, and I did exactly as you describe on pg. 135 of my manual (I built mine from the kit)

Then you move on to First layer configuration... As you have found, the Prusa First layer configuration tool is a little difficult to use. I find the 'Life Adjust 'Z' My Way' technique to be much easier to use.  Live Z only goes into negative values and this negative value, is the distance that the nozzle is lowered from the Pinda Sense point. 

This is where I'm having troubles - it seems that the nozzle is too far away and no matter how much neg. Z value (counterclockwise) I go during the test, the filament never gets close enough to squish into the build plate. I will try the "Life Adjust 'Z" My Way" approach and see if I have better luck with that.

I believe Prusa are happy with Live 'Z' values between 0.000mm and -2.000mmIf the extruder is still too high, when the live Z value is approaching -2.000mm it is best to reset  live Z to 0.00, readjust the Pinda slightly higher. then re adjust the Live Z. until you get a nice 'Squish'. 

It seems difficult at first, but gets easier with experience. 

regards Joan

RE: First Layer Calibration issues - cannot move nozzle down

1st-layer-calibration-220411

Okay - I'm at a lost here; I have not tried the alternate method "Life Adjust Z" yet but decided to recalibrate distance of my super-Pinda and rerun x,y,z calibration and then 1st layer calibration. See video above. As I adjust the live Z to neg (get closer to bed - counterclockwise ) it seems to have no affect and filament is not sticking to bed. I don't know if this is something I did when I built this kit over the weekend? I followed all the directions carefully and Wizard checks out all hardware as okay?

signed frustrated...

RE:

It's difficult to see just how high the nozzle is, from the video. one thing for sure, it is currently WAAAYYY too high. 

the Z height adjustment only moves the nozzle down one thousandth of a milimeter for every click (0.001mm per click)

You may need to lower the nozzle over a thousand clicks

On your previous video, you seem to have gone down about 760 clicks (Live Z value -0.760) 
I believe you still need to go down further.  

Initially, when you are too high, the extruded line tends to be wiggly  then as  you get the nozzle closer to the build plate the extruded filament  line becomes straighter, but is still round in cross section,(like you see at the beginning of the current video) and the filament just sits on the build plate surface, You still need live Z  to go lower, 
eventually the extruded filament should begin to squash between the nozzle and the build plate, this is when you start to get adhesion
the cross section of the filament will start to go oval 
you are using the textured build plate, so you need to lower Live Z, until the filament fills the texture in order to get Ultimate squish

at this point you should be able to scrape your fingernail across the extruded filament line, and feel it remain adhered to the build plate

regards Joan

RE: First Layer Calibration issues - cannot move nozzle down

Thanks Joan for taking thr time to be patient with me and my issue.

I agree with your assessment and wondering if this has anything to do with the fact that I built this as a kit? If I’m so far off and a 1000 clicks away how can I possibly get the nozzle down in the short time the test occurs?

Does the other test you suggest allow me to get past this issue? Perhaps when I manually adjust the Pinda I need to put more space (thicker ziptie) between it snd the bed thus bringing the nozzle closer to the bed during printing - although i would think that the Pinda would do its job here and figure that space out on its own…

RE: First Layer Calibration issues - cannot move nozzle down

the pinda only senses a separation distance between it, and the build plate, Hopefully the location of the pinda in the extruder housing sets the nozzle close enough to the build plate. and allow Live Z to resolve the rest of the adjustment. 
the screw thread on the Pinda has a 1mm thread pitch.  so you can raise the one millimeter at a time, by raising it one thread click

the 'Life adjust Z My Way' process takes longer than the prusa first layer calibration tool, which will allow longer for adjustment

but you can also do successive prusa first layer calibrations, and the printer should retain the previous setting, so that you can continue adjusting on the next session.

regards Joan

RE: First Layer Calibration issues - cannot move nozzle down

Success!   

Thanks Joan for guiding me thru this. I went back to my satin sheet and immediately had better luck with the zig-zag and square and tuning in my satin sheet for PLA. I put a little piece of white tape on my Z acme screw and could see as I turned the know counterclockwise that the Z was indeed turning abet very incrementally. Knowing that the live Z was indeed working correctly, I then went back to my textured sheet and tuned it until I got the PLA to stick and make a good zip zag. With the textured sheet, I heated up the nozzle from 215 to 220 to give it a little extra fluidity to soak into the texture. I also thoroughly clean both sheets with dish soap and dried them. 

I  think I'm now in business. My next task is to try and print successfully with ABS. I've built an enclosure for my printer and reading up on all the tips for printing ABS like a brim (which from my previous FDM printer I knew was necessary for ABS). Question: which sheet works best for ABS:  satin or textured?

Thanks again.

Mark