Stop and lift after purge line?
Hello, I would like to know if and how it is possible to add a stop and lift right after the purge line to clean the ooze off and around the nozzle.
It is not always needed but some filaments ooze more than others, especially after the 7 x 7 leveling.
any useful information would be appreciated.
Thanks, Eric
RE: Stop and lift after purge line?
Hi Eric,
this is a little like the process for inserting magnest,
Joel Telling covered this sort of thing in this video
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Stop and lift after purge line?
Joan, the video is interesting. I would like to know how to insert the M1 or stop code in prusaslicer itself, so i can have it spit out the code with the stop already inserted.
RE: Stop and lift after purge line?
You can modify the ‘start’ gcode in PrusaSlicer to do what you want and much more.
A well respected forum member here that goes by @bobstro has a website dedicated to helping others get the most from their Prusa MK3 printers (as well as a host of other interesting topics).
You can find some startup gcode he wrote to prevent oozing and do the bed leveling routine at a reduced nozzle temperature just for that reason here:
Many thanks to @bobstro for his contributions to this community. I have personally learned a great deal from his posts here and the website he hosts.
Cheers
RE: Stop and lift after purge line?
Based on my observations of how the "boogers" are forming on the nozzle, I think it would be great if Prusa modified the default purge line G-code slightly. Right now with my prints, there's often a loopy dealie forming on the nozzle during the 7x7 MBL. When the printer proceeds to the purge line, it lowers the extruder straight down, causing the hanging booger to smoosh right against the nozzle, smearing all over it. What could be done is to modify the procedure slightly, so instead of descending straight down, the extruder would perform a kind of "touch-and-go" manouver when it starts moving right still at height first and only then descend onto the plate. This way, there'd be more chance of the booger being smeared onto the plate's "service area" instead of all being rubbed into the nozzle's face. My previous printer was doing more or less that and it seemed to mostly work.
RE: Stop and lift after purge line?
You can modify the start gcode to do whatever you want it to do. See the link in my previous post.
I keep a small brass brush, roughy the size and shape of a toothbrush nearby to wipe off any stray blobs or goobers from the nozzle during warmup.
An easy way to effectively eliminate the smearing you’re experiencing, and without making changes to the start gcode, if you’re uncomfortable with that, is as follows:
1) Get a brass or stiff nylon brush to clean off the nozzle. Some have stated that they shorted out either the heater or thermistor wiring against the heater block and fried the main board doing this with a brass brush, so use caution or the nylon brush, sparingly so you don’t melt it.
1) Use the LCD control knob to raise the Z axis about 50 mm above the bed.
2) Use the LCD control knob to select ‘unload’ the filament. Choose your material at the prompt.
3) When the hotend reaches the proper temp, follow the prompts to unload the filament.
4) Use the brush to clean the nozzle of any stray bits or blobs of filament while the nozzle is at temp and stationary.
5) Start your print from the SD card, or the source utility of your choice. Do not load any filament prior to starting the print.
6) The printer will go through the ‘home’ and ‘mesh bed leveling’ routines. After bed leveling is complete, the extruder will return to the front-left corner of the bed as if it’s going to start the print.
The extruder will then move to the right side of the bed, raise up about an inch above the bed, and beep for you to push the button to unload the filament. Follow the unload instructions, even though there is no filament in the extruder. Once that’s done, follow the prompt to load the filament.
The LCD screen will prompt a response for 1) Did the filament load correctly and 2) Is the filament color as expected? Assuming the filament loaded correctly, I will typically respond that the color is not correct so I can extrude a bit more material to insure the hotend is primed and to give me a little circular pile of filament, which I will use to clear any nozzle residue in the next step. If the extruded filament begins to curl back on itself and stick to the nozzle, choosing ’color not correct’ and extruding more material will generally get this this to fall off by itself in the pile. If not, knock it off with the wire brush and extrude more material until you get a consistent string roping down off the nozzle.
Finally, when you’re satisfied with the extrusion, respond ‘Yes’ to the prompt, ‘Did the filament extrude correctly’ so you can start your print. Resist the temptation to wipe or pull off the string of filament hanging down because when you click ‘Yes,’ another inch of material will be extruded before the print head starts its move left to the position to print the purge line. Once the print head starts traveling, the string should stretch and break on its own, but, I use the wire brush to swipe the nozzle and catch the pile as the extruder is moving. Just be quick because you only have a second before the extruder begins to move downward towards the bed. You should get a clean purge line with no extra blobs or goobers, and then a clean print.
This all ended up being wordier than I anticipated, but I hope it is helpful to someone out there struggling to get a clean start to their prints. The more people learn about how their printer works, and how to get it to do things their way, the easier things get. It’s a journey so be patient and have fun!
Cheers