Loose filament spoiling first few layers
I have an MK3S and I am using Prusa's standard grey PLA. Printer is level, on latest firmware and fully calibrated, etc.
At the start of a new print and usually just after it's laid the small test bar print at the front of the print plate, the print head will ooze some additional, very fine filament out (like very fine, wispy strands). Unless I am quick / lucky and pull this additional filament out the way, it will lay across the area where the base is printed, resulting in some or all of the base being messed up. Sometimes the printer can carry on and ignore the messed up part, i.e. because it's not an integral to the base and sometimes it will spoil the base and I have to restart.
Does anyone know what causes this additional fine filament to ooze out and more importantly how to stop it?
Thanks.
Best Answer by bobstro:
At the start of a new print and usually just after it's laid the small test bar print at the front of the print plate, the print head will ooze some additional, very fine filament out (like very fine, wispy strands). Unless I am quick / lucky and pull this additional filament out the way, it will lay across the area where the base is printed, resulting in some or all of the base being messed up. Sometimes the printer can carry on and ignore the messed up part, i.e. because it's not an integral to the base and sometimes it will spoil the base and I have to restart.
Is there oozing between the completion of the prime line (the test bar) and the start of the part, or is this caused by filament that has oozed out during filament warmup? If during warmup, you might try a 2-step warming procedure. Rather than heat the nozzle up to full temp then wait for the bed, warm the nozzle up only to a "no ooze" temp (I use 160C), then wait for the bed, then finish warming up the nozzle immediately before printing the prime line. This will reduce the amount of time filament sits in the hot nozzle, reducing pre-print ooze. I've got my startup gcode documented here, including detailed notes on the warmup procedure. I also extrude a little "blort" of filament at the start of the prime line to help trap any oozing filament. Using this procedure, I've eliminated the little bed zits that can occur during mesh bed leveling, as well as the occasional string that forms after the prime line.
RE: Loose filament spoiling first few layers
I've been doing a bit more research and I suspect what I am seeing is 'stringing', which seems to be at its worst at the beginning of my prints and eventually settles down after 5-10 layers.
RE: Loose filament spoiling first few layers
Stringing can be caused by printing temps being too high, or retraction not being used. What're your print settings?
RE: Loose filament spoiling first few layers
Apart from the Z offset, I am pretty much using the default settings, including PLA temps of 215.
Also, what do you mean by retraction not being used, is that something I should be using and if so, how would I implement/enable it?
RE: Loose filament spoiling first few layers
At the start of a new print and usually just after it's laid the small test bar print at the front of the print plate, the print head will ooze some additional, very fine filament out (like very fine, wispy strands). Unless I am quick / lucky and pull this additional filament out the way, it will lay across the area where the base is printed, resulting in some or all of the base being messed up. Sometimes the printer can carry on and ignore the messed up part, i.e. because it's not an integral to the base and sometimes it will spoil the base and I have to restart.
Is there oozing between the completion of the prime line (the test bar) and the start of the part, or is this caused by filament that has oozed out during filament warmup? If during warmup, you might try a 2-step warming procedure. Rather than heat the nozzle up to full temp then wait for the bed, warm the nozzle up only to a "no ooze" temp (I use 160C), then wait for the bed, then finish warming up the nozzle immediately before printing the prime line. This will reduce the amount of time filament sits in the hot nozzle, reducing pre-print ooze. I've got my startup gcode documented here, including detailed notes on the warmup procedure. I also extrude a little "blort" of filament at the start of the prime line to help trap any oozing filament. Using this procedure, I've eliminated the little bed zits that can occur during mesh bed leveling, as well as the occasional string that forms after the prime line.
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RE: Loose filament spoiling first few layers
Thanks @bobstro, it's usually between the prime line and the start of the main print, with the resulting ooze sitting across the area of the main print. I'll give your suggestion a try as that sounds like a potential fix; many thanks for sharing your gcode notes, very useful, especially for someone like me, who is fairly new to 3d printing.
RE: Loose filament spoiling first few layers
One quick newbie question on using your g-code @bobstro, where do I put your start and end g-code in my exported g-code, are there specific sections that I should add these to or perhaps replace? For instance, I couldn't find a startup section but I could find a filament specific end section in my exported g-code.
As an aside, the ability to alter the g-code looks pretty powerful so I'll definitely be looking to learn more about adapting my exported g-code.
RE: Loose filament spoiling first few layers
OK, found it under the expert tab in Prusa Slicer, many thanks!
I'll mark this as answered 🙂