First layer will not print less than .30mm

rjenkinsgb

What happens if you change the Z offset for the BLTouch by 0.05 or 0.1mm?

That should adjust the nozzle height to the bed after the G30 zero set, without changing the displayed height.

Are you actually running a G30 in the middle of the bed (or your preferred print area) to set the Z height before starting the print? That's when the probe calibration really takes effect.

DNvM84

@rjenkinsgb
If you mean changing the Z in the G31 line, I have not tried that because I was concerned it would cause changes to prints like the .30mm thick part.

I am not familiar with the G30. But I don't think that is happening because homing of the axis happens in the back left corner. And Z Offset calibration happens in the front left.

Thank you for your help.

DNvM84

@o_lampe
So, I am ready to answer Q3.

I was able to baby step the nozzle -.10mm.

And when I measured the skirt and the cube I was around .22mm to .26mm.

But it still had no bonding between extrusions.

I had calibrated the extruder, but I will have to recheck it.

The question now is how to get the machine to print at .20mm on its own?

Thank you for your help.

rjenkinsgb

@dnvm84 said in First layer will not print less than .30mm:

I am not familiar with the G30.

Running a G30 probe is pretty much essential to accurately set the Z height, after homing the axes - unless you are homing Z using the probe?

Changing the Z in the G31 line will adjust the nozzle height relative to the bed.

Decreasing that by a small amount should should result in that much thinner first layer - you say it is about 0.05mm too thick, so decreasing the Z value in the G31 line by 0.05 should bring it to the correct printing height.

DNvM84

@rjenkinsgb
Hello, no currently there is a .10mm difference between set print thickness and actual measured thickness. But only when I try to print at .20mm. The thickness numbers, I believe you are referring to, are based on me doing baby steps. I adjusted a total of -.10mm.

So, my concern is if I adjust G31, and it allows me to print at .20mm, will it cause a .30mm first layer height setting to measure at .20mm.

Where do I find G30? If it is normally located in the config.g file I will have to add it.

Would you have an example of what that line should like?

Thank you for your support.

Phaedrux

@dnvm84 said in First layer will not print less than .30mm:

But I don't think that is happening because homing of the axis happens in the back left corner. And Z Offset calibration happens in the front left.

Ideally you should be using the same point near the center of the bed to measure and set the probe Z offset, and home the z axis. On very large beds like that you can have different results depending on where you're measuring.

Are you using mesh compensation yet? What does your heightmap look like?

Here are some example files for a modix big meter. PErhaps they will give you some ideas.
mesh.g homeall.g config.g bed.g

Phaedrux

@dnvm84 said in First layer will not print less than .30mm:

Where do I find G30? If it is normally located in the config.g file I will have to add it.

G30 is the command used to probe the current XY location.

rjenkinsgb

@dnvm84 said in First layer will not print less than .30mm:

Where do I find G30? If it is normally located in the config.g file I will have to add it.

It would normally be in the slicer start-up gcode section, as part of configuring the slicer for your specific machine.
eg. This is what I have in the start code for my CoreXY machine, using Prusaslicer.

This is a toolchanging machine, so ignore the tool part.

Look at the end of it -
The G32 runs "bed.g" which does the bed levelling; you don't need that with a single motor Z axis. (Or you could mage bed.g do the G30 probe).

It then move to approximately the centre of the bed (150,150)

And runs a G30 probe cycle.
That is what sets the ultimate Z position, so the nozzle height is correct from then on.

Prior to that, the Z zero is based on the home position rather than absolute calibration relative to the nozzle.

; Park any tool 
T-1                                       
; Home ALL axes
G28     
; Select tool zero  
T0
; Lift the nozzle                               
G1 Z15 F5000 

; Set Temperature - Bed - Wait
M140 S[first_layer_bed_temperature] 
;; TC_TEMP_INITIALIZE
;
M107       ;start with the fan off
G1 Z15.0 F{travel_speed} ;move the platform down 15mm
;
; Bed calibration
G32            ; Level across leadscrews, load heightmap
G0X150Y150
M30

DNvM84

Just a quick update. Modix has contacted me and somehow, I got tagged as spam. I will keep you updated on their suggestions along with working with all of you.

@phaedrux said in First layer will not print less than .30mm:

Are you using mesh compensation yet? What does your heightmap look like?

Yes I ran the Bed Compensation macro. heightmap 02-21-2022.csv

@rjenkinsgb said in First layer will not print less than .30mm:

It would normally be in the slicer start-up gcode section, as part of configuring the slicer for your specific machine.

I looked at the "Machine Settings/Start G-code", in CURA, and I do not have a G30 in my start code.
Should it be M30 like in your code?

Thank you everyone for your help.

DNvM84

@phaedrux

I compared your files to mine, and they are very different. In fact, I don't have a mesh.g file.
bed.g homeall.g config.g

I am getting really close. I edited line G31 "Z". Now I just need to determine if the table compensation is even working. Normally I don't care because I usually only print smaller items. But I have some items to print that will use more of the bed.

Thank you for all of your help.

rjenkinsgb

@dnvm84 said in First layer will not print less than .30mm:

I looked at the "Machine Settings/Start G-code", in CURA, and I do not have a G30 in my start code.
Should it be M30 like in your code?

Yes, that should help.

Try running it manually first (from DWC or Paneldue) in the middle of the print area, and check the Z height is then OK?

Another thing to be cautious of, is only calibrate the Z height for the probe when the nozzle is hot, unless it's a brand new one!

Otherwise, it may have a small amount of set plastic on the end that gives you a false impression of height when doing a paper test etc.

DNvM84

So here is the latest update.

The printer is printing at the thinner layers.

I had to adjust the G31 "Z" value.

I plan to continue testing to be 100% sure everything is the way I want it.

@Phaedrux
When you posted the photo of your code. At the very bottom you have a M30. According to Duet that code is to delete a file. Is that supposed to be the G30 you were trying to point out?

I still hope to learn more about the G30 code.

Thank you everyone for your help.

rjenkinsgb

@dnvm84 said in First layer will not print less than .30mm:

I still hope to learn more about the G30 code.

G30 causes a single Z probe cycle; with no other parameters, the Z height is set to whatever the Z preset value for the probe is, as it is triggered.

So, as long as the preset is correct for the difference between the probe trigger and nozzle, the nozzle should then be at the exact programmed height for printing.

Phaedrux

@dnvm84 said in First layer will not print less than .30mm:

I still hope to learn more about the G30 code.

https://docs.duet3d.com/en/User_manual/Reference/Gcodes#g30-single-z-probe

First layer will not print less than .30mm

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