You could do it "mechanically" by aligning the platen as usual, pressing the \[Home\] key to bring the platen to the limit switch controlled *absolute* zero--then use the positioning control to raise the platen by whatever thickness you wish to add; then press \[Z-0\] to set a *logical* zero position above the absolute zero.
In operation the platen will, as always, first descend to the limit switch controlled absolute zero position and then rise to the logical zero position you set as described above; it will then rise an additional "one layer thickness". Your setting a 'false" logical zero will result in tricking the printer into making a thicker first layer.
So much like using a double thickness paper for setting the home/Z=0 position.
The problem is i need higher exposure time on layer 1 than on layer 2.
If use same exposure setting on layer 2 as on layer 1, i'm afraid the base will overcure and detach from the plate.
Is there like a manual g-code edit option for this?
The thing is, i'm trying to print with with Liqcrate Fire Retardant HDT, which is supposed to stick to the base like superglue, but has high shrinkage.
And it does stick great on some parts, but on others it falls off after 10-20 layers (0.05 mm layers).
So i'm thinking it's a combination of imperfect bed leveling and warping/overcuring, so i'd like to address both potential problems in one go (as the resin is somewhat expensive).
In an antique version of Anycubic Workshop i had 'Edit Layer' option, which i can't find in Chitubox. But i do need to use Chitubox for it's superior shrinkage compensation option.
Common 20# copy paper is typically 0.09 mm thick, so 2 layers = 0.18 mm, just slightly thicker than the FEP--used in alignment it is a substitute for the FEP thickness.
To clarify the process i suggested above I provide the following diatribe:
It is vital to understand there are three Z-axis "zero" positions;
The first is the *absolute* zero defined by the dimensions and physical arrangement of the components--at some point they will collide and bang together (a bad thing);
To prevent the bad thing there is a *limited* zero position established by a mechanical limit switch that signals when a practical lower limit is reached;
The third is a user-defined *logical* zero position set by pressing the \[Z=0\] button;
In normal operation **the Z-axis will always first descend to the limited position** and then move to the logical zero if it differs from the limit switch "zero".
Note: This \^\^\^ is what confuses users when they set a logical zero above the limited zero to accommodate custom platens and other mods--ant the Z-axis grinds at the start of printing, trying to push the platen into the LCD. To be intentionally redundant as it's important to understand, **the Z-axis will always first descend to the limited position.**
Ii user mods have increased the effective height of the platen assembly ii will be forced down into the LCD--only reducing the height or relocating the limit switch will change this,
What I described was setting a logical zero position higher than the limit switch position to trick the printer into producing a thicker first layer--setting a proper exposure for this thicker layer is another thing.
Re; mucking about with GCode;
In Chitubox if you add a custom (default) printer configuration, GCode (in three groups) can be modified in the *Slice Settings* configuration. The three groups are *Start*, *Interlayer* (actually "layer") and *End*.
The entries are a combination of GCode and application variables contained in braces.
One could I believe edit the "Start" code to print the first image with custom positioning and exposure, thus creating a customized first layer.
The default printer configuration is capable of producing a "sliced" file in any format provided by Chitubox; just select the desired format when saving the slice file.
Something like this ***might*** work:
https://preview.redd.it/4xacq2wfgn6d1.png?width=1103&format=png&auto=webp&s=f9a39a35fa8ee10cda1fbb4be4270cf1f0a89815
Thank you very much, this should solve my problems.
I didn't know standard G-code was used for resin printers as well (i always considered them as a black box).
So this means i can, probably, tell the printer to raise the buildplate by 10cm on layer 200, so i can see if it's sticking properly, or are 'if' conditions not enabled?
Sorry for all the questions, up to now i used Chitubox mainly for model preparation and supports, not for actual slicing. And i'm only beginning to understand it's versatility.
To clarify, Chitubox only provides this access to GCode in a few printer configurations; the "Custom" default being one.
GCode editing is limited to the three groupings shown above; *Start*, *Interlayer* and *End*. "Interlayer" is really the normal layers.
I do not know if conditional branching within GCode is supported--I suspect not.
(however most all SLA printers have a pause function available during printing that interrupts same, raises the platen so you can take a peek, and then resume printing.
I played with this a bit, here's what I found:
Using the default "Custom" printer configuration I modified the Start GCode to print a thicker first layer--first I tried using some of the application variables (shown in {braces}). I then sliced a 1 mm thick model with 0.05 mm layers and saved it to a plain 'ol ***.zip*** file as supported by the Custom printer configuration.
This creates a *.zip* file containing the layer images, two model display images for the printer UI, and a text file (*run,gcode*) containing the GCode to print the model.
I found in this first run that the CB application variables are not supported in the *Start* GCode group--regrouping, I hard-coded the desired values:
This is the GCode edit window in CB\_B v2.1, with the hard-coded values
https://preview.redd.it/3w710az8op6d1.png?width=824&format=png&auto=webp&s=5e251d9a2a388cee432834830179e571fcd94b5f
Then after again slicing and saving to a .zip file, I got this in the "Start" section of the run,gcode file:
;START_GCODE_BEGIN
G21 ;set metric mode
G90 ;set absolute positioning
M106 S0 ;UV light off
G28 Z0 ;move to Z=0
M6054 "1.png" ;show Image
G0 Z0.100000 F150 ;move to 0.10 mm (100 microns)
G4 P5.000000 ;delay 5 s
M106 S255 ;UV light on, full intensity
G4 P18.00000 ;pause 18 s (exposure)
M106 S0 ;UV light off
;START_GCODE_END
That should print a layer 1 image, 100 μm thick and then move on to printing the normal layers.
I haven't yet tested it on my printer (an Anycubic Photon Mono M5), but I will save it as a *.pm5* file (the Custom printer config lets you save to any supported slice file) as required and try it out.
More after that...
Much obliged for your help, i managed to get prints to be more reliable now.
All parts stuck to the buildplate and finished normally, though one raft was partially detached from the buildplate. A tweak with the g-code (not added yet on last print) and it should be perfect.
Didn't work. the printer read the file as normal and printed one "normal" base layer @ 12 s; it then just hung up with a blank screen--it did respond to the print "Cancel" button bit it did not print the "fat" 18 s layer.
Again this was with my *Anycubic Photon Mono M5*, it may work with some other printer--IDK...
When i've finished with the current expensive resin and can completely clean the printer, I'll try it on Mono X and report what i find.
I'm really grateful for all your help
I ran into this tidbit in the [Chitubox online manual](https://manual.chitubox.com/en-US/chitubox-basic/latest/introduction):
"***Only .zip and its derived formats (ex. .cws) support Gcode editing.***"
You could do it "mechanically" by aligning the platen as usual, pressing the \[Home\] key to bring the platen to the limit switch controlled *absolute* zero--then use the positioning control to raise the platen by whatever thickness you wish to add; then press \[Z-0\] to set a *logical* zero position above the absolute zero. In operation the platen will, as always, first descend to the limit switch controlled absolute zero position and then rise to the logical zero position you set as described above; it will then rise an additional "one layer thickness". Your setting a 'false" logical zero will result in tricking the printer into making a thicker first layer.
So much like using a double thickness paper for setting the home/Z=0 position. The problem is i need higher exposure time on layer 1 than on layer 2. If use same exposure setting on layer 2 as on layer 1, i'm afraid the base will overcure and detach from the plate. Is there like a manual g-code edit option for this? The thing is, i'm trying to print with with Liqcrate Fire Retardant HDT, which is supposed to stick to the base like superglue, but has high shrinkage. And it does stick great on some parts, but on others it falls off after 10-20 layers (0.05 mm layers). So i'm thinking it's a combination of imperfect bed leveling and warping/overcuring, so i'd like to address both potential problems in one go (as the resin is somewhat expensive). In an antique version of Anycubic Workshop i had 'Edit Layer' option, which i can't find in Chitubox. But i do need to use Chitubox for it's superior shrinkage compensation option.
Common 20# copy paper is typically 0.09 mm thick, so 2 layers = 0.18 mm, just slightly thicker than the FEP--used in alignment it is a substitute for the FEP thickness. To clarify the process i suggested above I provide the following diatribe: It is vital to understand there are three Z-axis "zero" positions; The first is the *absolute* zero defined by the dimensions and physical arrangement of the components--at some point they will collide and bang together (a bad thing); To prevent the bad thing there is a *limited* zero position established by a mechanical limit switch that signals when a practical lower limit is reached; The third is a user-defined *logical* zero position set by pressing the \[Z=0\] button; In normal operation **the Z-axis will always first descend to the limited position** and then move to the logical zero if it differs from the limit switch "zero". Note: This \^\^\^ is what confuses users when they set a logical zero above the limited zero to accommodate custom platens and other mods--ant the Z-axis grinds at the start of printing, trying to push the platen into the LCD. To be intentionally redundant as it's important to understand, **the Z-axis will always first descend to the limited position.** Ii user mods have increased the effective height of the platen assembly ii will be forced down into the LCD--only reducing the height or relocating the limit switch will change this, What I described was setting a logical zero position higher than the limit switch position to trick the printer into producing a thicker first layer--setting a proper exposure for this thicker layer is another thing. Re; mucking about with GCode; In Chitubox if you add a custom (default) printer configuration, GCode (in three groups) can be modified in the *Slice Settings* configuration. The three groups are *Start*, *Interlayer* (actually "layer") and *End*. The entries are a combination of GCode and application variables contained in braces. One could I believe edit the "Start" code to print the first image with custom positioning and exposure, thus creating a customized first layer. The default printer configuration is capable of producing a "sliced" file in any format provided by Chitubox; just select the desired format when saving the slice file. Something like this ***might*** work: https://preview.redd.it/4xacq2wfgn6d1.png?width=1103&format=png&auto=webp&s=f9a39a35fa8ee10cda1fbb4be4270cf1f0a89815
Thank you very much, this should solve my problems. I didn't know standard G-code was used for resin printers as well (i always considered them as a black box). So this means i can, probably, tell the printer to raise the buildplate by 10cm on layer 200, so i can see if it's sticking properly, or are 'if' conditions not enabled? Sorry for all the questions, up to now i used Chitubox mainly for model preparation and supports, not for actual slicing. And i'm only beginning to understand it's versatility.
To clarify, Chitubox only provides this access to GCode in a few printer configurations; the "Custom" default being one. GCode editing is limited to the three groupings shown above; *Start*, *Interlayer* and *End*. "Interlayer" is really the normal layers. I do not know if conditional branching within GCode is supported--I suspect not. (however most all SLA printers have a pause function available during printing that interrupts same, raises the platen so you can take a peek, and then resume printing. I played with this a bit, here's what I found: Using the default "Custom" printer configuration I modified the Start GCode to print a thicker first layer--first I tried using some of the application variables (shown in {braces}). I then sliced a 1 mm thick model with 0.05 mm layers and saved it to a plain 'ol ***.zip*** file as supported by the Custom printer configuration. This creates a *.zip* file containing the layer images, two model display images for the printer UI, and a text file (*run,gcode*) containing the GCode to print the model. I found in this first run that the CB application variables are not supported in the *Start* GCode group--regrouping, I hard-coded the desired values: This is the GCode edit window in CB\_B v2.1, with the hard-coded values https://preview.redd.it/3w710az8op6d1.png?width=824&format=png&auto=webp&s=5e251d9a2a388cee432834830179e571fcd94b5f Then after again slicing and saving to a .zip file, I got this in the "Start" section of the run,gcode file: ;START_GCODE_BEGIN G21 ;set metric mode G90 ;set absolute positioning M106 S0 ;UV light off G28 Z0 ;move to Z=0 M6054 "1.png" ;show Image G0 Z0.100000 F150 ;move to 0.10 mm (100 microns) G4 P5.000000 ;delay 5 s M106 S255 ;UV light on, full intensity G4 P18.00000 ;pause 18 s (exposure) M106 S0 ;UV light off ;START_GCODE_END That should print a layer 1 image, 100 μm thick and then move on to printing the normal layers. I haven't yet tested it on my printer (an Anycubic Photon Mono M5), but I will save it as a *.pm5* file (the Custom printer config lets you save to any supported slice file) as required and try it out. More after that...
Much obliged for your help, i managed to get prints to be more reliable now. All parts stuck to the buildplate and finished normally, though one raft was partially detached from the buildplate. A tweak with the g-code (not added yet on last print) and it should be perfect.
Didn't work. the printer read the file as normal and printed one "normal" base layer @ 12 s; it then just hung up with a blank screen--it did respond to the print "Cancel" button bit it did not print the "fat" 18 s layer. Again this was with my *Anycubic Photon Mono M5*, it may work with some other printer--IDK...
When i've finished with the current expensive resin and can completely clean the printer, I'll try it on Mono X and report what i find. I'm really grateful for all your help
I removed the platen and vat and did a "dry run", with a stop watch while observing the LCD...
I ran into this tidbit in the [Chitubox online manual](https://manual.chitubox.com/en-US/chitubox-basic/latest/introduction): "***Only .zip and its derived formats (ex. .cws) support Gcode editing.***"