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Edited by policGregValiant 1,409
It is possible to restart the gcode from any point within the gcode. Homing and synchronizing the axes are problems. The main problem is that with so many models on the build plate - is one going to come loose? That would be a concern.
The second problem is that re-homing does not guarantee that the 0,0,0 will be EXACTLY the same as it was for the start of the print. I have found that there can be a layer shift of up to 0.5mm. The end stop switches are not perfectly "repeatable".
To print the gcode starting at a Z of 9.3:
- Open the gcode file in a text editor.
- Do a "Save As" of the existing gcode file to give it another name.
- Delete everything in the gcode file before the line ";LAYER:91".
- Paste in the code below as a new "StartUp Gcode" at the very beginning of the new file. You are responsible for checking the numbers.
- The "Z" must home at an open spot on the build plate. I have chosen X200 Y160 because in your photo it looks like that position is open to safely drop the Z. X120 Y0 also looks to be a good spot.
- Insure that the nozzle starts out at least 10mm above the prints. You can move it manually if you must.
M140 S40 ;Set Bed temp
M190 S40 ;Wait for bed
M104 S212 ;Hot end temp
M109 S212 ;Wait for hot end
M105 ;Report Temps
M220 S100 ;Reset Feed rate
M221 S100 ;Reset Flow rate
G28 X Y ;Home the X and Y at whatever Z they happen to be at.
G1 F2400 X200 Y160 ;CHECK THIS it looks like this position is open so the Z can home at this point.
G28 Z ;Home Z
M106 S191 ;Fan at 75%
G0 F1200 Z19.3 ;Move the Z to restart height + 10
G1 E15 F1500 ;Prime the nozzle. You need to be ready to grab the extruded plastic with tweezers.
G4 S2 ;Pause for 2 seconds to allow you to grab the plastic with the tweezers.
G0 F7200 X22.91 Y43.132 ;Move to XY restart location of the first extrusion of Layer 91.
G92 E1252.28641 ;Set extruder -4 prime
G0 F300 Z9.3 ;Drop 10 to Resume Z
G0 F7200 ;Set travel Feed rate
;LAYER:91 ;Your existing layer line at a Z of 9.3
The X, Y, Z and E numbers above were taken from your file. YOU are responsible for checking my work.
If you were printing from the SD card then you may need to re-format the card. If part of that file was written to "bad sectors" on the card then yes, there could be a gap in the code.
If you were printing via USB it has it's own issues and can "pause" abruptly. That doesn't sound like what happened.
Edited by GregValiant
Thanks so much for your help. Yes, my prusa i3 prints from an sd card. Both to verify your reasonable supposition and to follow your suggestion I must open / edit the gcode - so now I have to bypass that a so long text file tends to block both the editor and my whole system - possibly opening it on another pc.
Yes, it worked perfectly! Layer 91 was just the right one, and the printer finished smoothly its job. Homing axis was not a problem, since I had already removed the circular cooler around the hot end because of its dimensions. So my blocked printing solved on just one blow. Though pieces have come up not so perfect, as you can see in the picture, with a shift of about 1 mm on X axis and something less on Y axis, more than I would expect (pieces should turn usable with a bit of filing, anyway) - your printer's endstops are more precise. Thanks again.
GregValiant 1,409
A save is a save and you can only do so much as homing is always an issue.
Marlin actually has codes to make restarts very precise BUT things have to be planned ahead. My Ender 3 Pro has a maximum Stepper Disarm time of 14400 seconds (4 hours) that is much higher than the default 120 seconds. If I am doing a long print or an "iffy" print I add M84 S14400 near the beginning of the file. If I have to pause for some reason, or if something bad happens with the print, I have time to configure a script to restart from any location within the file.
I actually automated this and included it in my printing app.
Here ya go...Greg's Toolbox for Windows. There are instructions and a readme file. The program is unsigned and if you decide to try it you will probably have to fool your anti-virus to get it to install. There is also an uninstall.
Below is a shot of the "Recovery" page. It requires some practice but for the most part you just need to make sure the initial prime of the extruder isn't going to leave a blob.
In the textbox in the screenshot is a recovery script. The program will send the script and restart a gcode file from the byte location within the file. There is no need to create a special file for the restart.
I don't know your printer but Gcodes are Gcodes and it should work provided your firmware supports M26 and some other commands.
Edited by GregValiant
If I've understood well, your software allows to resume a print without having to load a new gcode file and home axis again, but with the printer remaining on the same gcode partially executed. Through your pc connected to the printer, you write within the Toolbox sw the needed script and insert it in the gcode - finally you resume the paused print. And to have time to do that, every gcode generated by the slicer (Cura) must always be modified to increase the stepper disarm value - thing which is automated by Toolbox, right? And of course, to allow that to be done you must keep a pc with Toolbox connected to the printer.
On the screenshot of Toolbox I can see several tabs, from wich I guess it must have many features. Anyway, it requires to be acquainted with gcode commands and a printer with wi-fi or usb ports, which mine doesn't have. And I think that, as long as I print only from time to time, the simplest way will be the best for me.
GregValiant 1,409
I agree. Simple is best. It is rarely a word associated with 3D printing.
The PC must be connected to the printer via USB. If you connect the USB cable to the printer it will see the 5volt connection and that will cause the printer to re-boot and the print will fail. That is true on any printer as the 5volt signal is used by the firmware of many printers to signal an external reset.
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