Nozzle started hitting the bed during a print

[glen4cindy 1]

I'm just getting started with 3D printing and using Cura and I'm having some successes and failures along the way. This is one of each.

 

I had a print going that had 3 pieces. Without realizing it I still had a setting set in Cura that printed each piece one by one. This turned out to be a good thing, I suppose.

 

The first piece was printed successfully. Then it got to layer 137 or 138. The nozzle started hitting the bed. It moved a bit more and made more noise like it was dragging.

 

I'm almost certain my bed is level. I had to remove the glass to clean it before this print and I'm pretty sure I ran a level before I ran the print job.

 

Unfortunately, I didn't save the project so I can load it to be certain but, would Cura allow me to put something below the bed? Would it command the printer to move the nozzle lower than the level of the glass?

 

I used Prusa's GCode viewer to view the gcode and it doesn't look like the 2nd item is lower than the bed.

 

How can I tell for sure before I attempt to print again? Thanks in advance.

CFFFP_Cindy's_Charger_Holder.gcode

[Slashee_the_Cow 283]

2 hours ago, glen4cindy said:

Unfortunately, I didn't save the project so I can load it to be certain but, would Cura allow me to put something below the bed? Would it command the printer to move the nozzle lower than the level of the glass?

Anything below the print bed will just get cut off during slicing, I can tell you that much. Give me a bit to look through your gcode and I'll see if anything stands out.

[Alain_D 4]

I see only 134 layers ?

Something is strange with supports and I think that they are missing at some places.

[Slashee_the_Cow 283]

Okay, I'm sorry, but I can't help it, I'm a critic. Who did this startup gcode? Or is your printer just really strange?

M140 S60 ; SLASHEE: Not needed at all because no time passes between this and the M190 below.
M105 ; SLASHEE: This is just "report temperature". It won't do anything in startup gcode because nothing is waiting for it. And even if it was, it's only going to report the temperature immediately after you run the M140, i.e. with no time at all to heat up
M190 S60
M104 S200 ; SLASHEE: See comment on line 1
M105 ; SLASHEE: See comment on line 2
M109 S200
M82 ;absolute extrusion mode
G28 ; home all axes
M420 S1 ; SLASHEE: Friendly notice: some printers will do this automatically.
M117 ; Purge extruder ; SLASHEE: WTF? M117 is "Set LCD Message" and makes a message appear on the printer's screen (in theory)
G92 E0 ; reset extruder
G1 Z1.0 F3000 ; move z up little to prevent scratching of surface ; SLASHEE: You haven't explicitly set absolute positioning (G90), and while it's the default in Marlin, it's just nice to let people know ; Also by convention G1 should be used for extrusion moves while G0 should be used for travel moves like this
G1 X2 Y20 Z0.3 F5000.0 ; move to start-line position ; SLASHEE: See above comment about travels using G0
G1 X2 Y200.0 Z0.3 F1500.0 E15 ; draw 1st line
G1 X2 Y200.0 Z0.4 F5000.0 ; move to side a little ; SLASHEE: See above about G0
G1 X2 Y20 Z0.4 F1500.0 E30 ; draw 2nd line
G92 E0 ; reset extruder
G1 Z1.0 F3000 ; move z up little to prevent scratching of surface
G92 E0 ; SLASHEE: You just did that two lines ago and you haven't extruded since
G92 E0 ; SLASHEE: You just did that LAST LINE and you haven't extruded since
G1 F3600 E-2 ; SLASHEE: Unless you're printing a flexible filament like TPU, you shouldn't need to retract that far with a direct drive extruder. And if you don't have a direct drive extruder then god damn is 60mm/s fast for a Bowden extruder and you're not retracting far enough

 

Anyways, looking at the gcode (as code, not as a preview), there's no commands for the nozzle to go below 0.12mm (not that you specify absolute positioning, but it's the default). The only relative move on the Z axis 

 

By layer 137-138 I'm assuming you mean somewhere between layers 2 and 5 (depending whether you're doing 0 based counting) of the second object - I looked around there and couldn't see anything standing out as unusual.

 

Oh god, now my inner critic on your end gcode. I'm sorry. I can't help it. I swear it's well intentioned, trying to help people, but I know it comes across as picking even the tiniest of nits:

G1 F3600 E1358.3259
M140 S0
M107 ; SLASHEE: I wouldn't turn off the fan until I'm away from the print, personally.
G91; relative positioning
G1 Z1.0 F3000 ; move z up little to prevent scratching of print
G90; absolute positioning
G1 X0 Y0 F1000 ; prepare for part removal
M104 S0; turn off extruder
M140 S0 ; turn off bed ; SLASHEE: You already did that on the second line
M84 ; disable motors ; SLASHEE: Unless you have a good reason, you shouldn't unlock the Z motor or it'll make it VERY easy for the Z axis to move out of position
M420 S0 ; SLASHEE: Why disable automatic bed levelling?
M106 S0 ; turn off fan ; SLASHEE: You did this already on the third line
M82 ;absolute extrusion mode ; SLASHEE: You're not extruding anything after this. Why bother setting the mode?
M104 S0 ; SLASHEE: You already did this six lines ago, this ain't gonna make it happen any quicker.

 

Anyways, I don't see any reason that printing this gcode should cause your nozzle to decide to faceplant into the bed. If you can repeat it and it happens at the exact same point, that warrants further investigation. But in this case I'd be looking more at potential hardware problems (like make sure whatever drives your Z axis is at the correct tension).

[glen4cindy 1]

13 hours ago, Slashee_the_Cow said:

Okay, I'm sorry, but I can't help it, I'm a critic. Who did this startup gcode? Or is your printer just really strange?

M140 S60 ; SLASHEE: Not needed at all because no time passes between this and the M190 below.
M105 ; SLASHEE: This is just "report temperature". It won't do anything in startup gcode because nothing is waiting for it. And even if it was, it's only going to report the temperature immediately after you run the M140, i.e. with no time at all to heat up
M190 S60
M104 S200 ; SLASHEE: See comment on line 1
M105 ; SLASHEE: See comment on line 2
M109 S200
M82 ;absolute extrusion mode
G28 ; home all axes
M420 S1 ; SLASHEE: Friendly notice: some printers will do this automatically.
M117 ; Purge extruder ; SLASHEE: WTF? M117 is "Set LCD Message" and makes a message appear on the printer's screen (in theory)
G92 E0 ; reset extruder
G1 Z1.0 F3000 ; move z up little to prevent scratching of surface ; SLASHEE: You haven't explicitly set absolute positioning (G90), and while it's the default in Marlin, it's just nice to let people know ; Also by convention G1 should be used for extrusion moves while G0 should be used for travel moves like this
G1 X2 Y20 Z0.3 F5000.0 ; move to start-line position ; SLASHEE: See above comment about travels using G0
G1 X2 Y200.0 Z0.3 F1500.0 E15 ; draw 1st line
G1 X2 Y200.0 Z0.4 F5000.0 ; move to side a little ; SLASHEE: See above about G0
G1 X2 Y20 Z0.4 F1500.0 E30 ; draw 2nd line
G92 E0 ; reset extruder
G1 Z1.0 F3000 ; move z up little to prevent scratching of surface
G92 E0 ; SLASHEE: You just did that two lines ago and you haven't extruded since
G92 E0 ; SLASHEE: You just did that LAST LINE and you haven't extruded since
G1 F3600 E-2 ; SLASHEE: Unless you're printing a flexible filament like TPU, you shouldn't need to retract that far with a direct drive extruder. And if you don't have a direct drive extruder then god damn is 60mm/s fast for a Bowden extruder and you're not retracting far enough

 

 

I'm confused. Where did this come from? I especially don't recognize "SLASHEE" The code file I attached was generated by Cura when I sliced the STL file I wanted to print.

 

There is a startup code in the printer profile but it doesn't look like this. The startup code that's in Cura came from Mingda.

[glen4cindy 1]

14 hours ago, Alain_D said:

I see only 134 layers ?

Something is strange with supports and I think that they are missing at some places.

I don't understand this. I see the gcode file says there are only 134 layers. I was watching the progress of the print in Octoprint. It was reporting layer 136 or 137. I double checked this with Prusa's Gcode viewer.

 

It's the 2nd object that is getting ready to print. The charger holder. As soon as it starts printing the nozzle begins crashing into the bed. Nothing at all unusual happened when it was printing the arm.

[Slashee_the_Cow 283]

2 hours ago, glen4cindy said:

I'm confused. Where did this come from? I especially don't recognize "SLASHEE" The code file I attached was generated by Cura when I sliced the STL file I wanted to print.

 

There is a startup code in the printer profile but it doesn't look like this. The startup code that's in Cura came from Mingda.

The ; SLASHEE parts are comments I added (please look to the left and see what it says before "_the_Cow") where I thought there were issues (a semicolon starts a comment in gcode, I added my own even when a line had a comment to make it clear it was from me). The code itself is from the start and end of your gcode file, so it's the startup/end code set in Cura for your printer, except perhaps (hopefully) with replacement patterns replaced by the correct values.

 

2 hours ago, glen4cindy said:

It's the 2nd object that is getting ready to print. The charger holder. As soon as it starts printing the nozzle begins crashing into the bed. Nothing at all unusual happened when it was printing the arm.

Have you tried it again yet? There's no reason in the gcode for it to do that, the lowest it ever commands the nozzle go down to is 0.12mm, and it does that on both objects, so there's no good reason it should behave any differently on the second. Hardware issues and one off brain farts from the motherboard are both possible options,

[glen4cindy 1]

On 1/28/2024 at 4:58 PM, Slashee_the_Cow said:

The ; SLASHEE parts are comments I added (please look to the left and see what it says before "_the_Cow") where I thought there were issues (a semicolon starts a comment in gcode, I added my own even when a line had a comment to make it clear it was from me). The code itself is from the start and end of your gcode file, so it's the startup/end code set in Cura for your printer, except perhaps (hopefully) with replacement patterns replaced by the correct values.

 

Have you tried it again yet? There's no reason in the gcode for it to do that, the lowest it ever commands the nozzle go down to is 0.12mm, and it does that on both objects, so there's no good reason it should behave any differently on the second. Hardware issues and one off brain farts from the motherboard are both possible options,

I understand now. Thanks for clearing this up.

 

The start and end gcodes had to have come from the printer config I downloaded from Mingda. I didn't write them. I didn't even know I had to "slice" an .stl file before I could 3D print it much less anything about start and end codes before I started learning about using this printer.

 

Thanks for clearing up my worry about the printer gladly planting itself below the surface if it were told to do so.

 

I actually didn't repeat the same print. Since I had accidentally configured it to print the objects one at a time I resliced with the two remaining objects.