Prevent filament from flowing out before start of print  

RE: Prevent filament from flowing out before start of print

When are you doing the final nozzle warmup? If you do it right before you print the prime line, and excess should get caught in the line. I have mine print a little blob of filament at the start of the line for exactly this purpose. See line 53.

RE: Prevent filament from flowing out before start of print

Posted by: @bobstro

When are you doing the final nozzle warmup? If you do it right before you print the prime line, and excess should get caught in the line. I have mine print a little blob of filament at the start of the line for exactly this purpose. See line 53.

The final nozzle warm up is right before the prime line is printed.  After the mesh bed level is complete, the z axis moves up 30 and starts the final nozzle warm up to 215C.  But I get quite a lot of filament oozing out before the prime line prints. 

RE: Prevent filament from flowing out before start of print

Bump.  Is there a solution to this?  It does not seem to matter what brand of filament I am using.  I always get a line of filament oozing out of the nozzle just before printing the prime line as the nozzle warms up.  Some filaments will only come out a little, others will have a string an inch or more long coming out in the time it takes for the nozzle to go from 160 to 215.  

Any update?

I’m having the exact same issue, I have tried so many trouble shooting without success. I already replace my nozzle and recalibrated and also open up and cleaned out the extruder. My issue might be worst than yours. My print would pause after writing an inch of first layer. 

Filament oozing

Posted by: @payluder

I’m having the exact same issue, I have tried so many trouble shooting without success. I already replace my nozzle and recalibrated and also open up and cleaned out the extruder. My issue might be worst than yours. My print would pause after writing an inch of first layer. 

I never did find a clear solution to this.  One thing I've noticed is that dry filament does not ooze out nearly as much as wet filament.  

Change your startup Gcode

You can change the startup G code to minimize the oozing - if your filament has any moisture in it, as soon as it heats up, the steam pushes the extra out of the nozzle - so dry your filament is the first thing you can do.  The second thing you can do is change the order of the final nozzle warm up - delay it to last instead of before the bed mesh leveling.  That takes modifying the startup Gcode that is stored in the GCODE file (the printer has no startup cycle - it only does what the Gcode tells it).  You can do that in prusa slicer - because that is the program that inserts the startup Gcode into the final print file.

prevent oozing

Posted by: @dan-rogers

You can change the startup G code to minimize the oozing - if your filament has any moisture in it, as soon as it heats up, the steam pushes the extra out of the nozzle - so dry your filament is the first thing you can do.  The second thing you can do is change the order of the final nozzle warm up - delay it to last instead of before the bed mesh leveling.  That takes modifying the startup Gcode that is stored in the GCODE file (the printer has no startup cycle - it only does what the Gcode tells it).  You can do that in prusa slicer - because that is the program that inserts the startup Gcode into the final print file.

I've done all this.  The nozzle is heated to 160, then mesh bed leveling, then nozzle heats to 230 (petg) as the last step before printing.  

The wet filament issue is also hard to tackle.  I print almost constantly and I've found that by the time I get about half way through a roll of filament the oozing starts to get worse, but I can't stop printing to take the roll off and dry it.  

It's not a huge deal.  I've gotten used to simply using a very small soft nylon brush to wipe the excess oozing off right before the print.  

Prime line should pull away any ooze

Posted by: @buckeyestargazer

 [...] I never did find a clear solution to this.  One thing I've noticed is that dry filament does not ooze out nearly as much as wet filament.  

I think that's your solution: Get rid of the saturated filament. You're very likely to have print quality and part strength issues with moist filament. A dehydrator is a good investment for anybody doing 3D printing.

So far as any last ooze that comes out after leveling and before the prime line prints, you can usually deal with this in your prime line routine:

1. Print a little blob at the start of the prime line. This will usually catch any ooze in case you miss it. I use 2mm but more may help.
2. Print a little wider section at the end of the prime line to push a bit more out, hopefully pulling away any ooze.
3. Do a little "wipe" jog at the end of the prime line. You can have the start gcode do a little square or other trapping pattern here.

If you're getting so much ooze that this doesn't work, definitely dry that filament a bit longer before starting!

get more than one roll

"can't take the roll off to dry it" - well, priorities then.

Temperature?

I know that the cold-pull instructions, that I found here, have you heating the plastic to quite a bit hotter than normal in order to FULLY fill the hot end. Perhaps the opposite will help you.
Try knocking 5-10 degrees off of a small print and seeing if maybe you need to modify the profile for your plastic.