Two More Noob Questions - Extruder Problems and Bed Cleaning

Tried my first real print tonight. It was supposed to be the base for a sink organizer. Very simple design, but big - it takes up nearly the entire width of the X-axis of my A350.

Things were going well at first, but then I noticed the machine had slowly stopped extruding. I stopped the print, opened the extruder and noticed that the filament was all “gummed up” near where the drive gear touches it. It looked like the drive gear was slipping and that caused a mushroom of filament to form around the lower part of the extruder that prevented more filament from being pushed into the heating block. I removed the filament, cut off the lousy part, and was able to manually push it through the heating block with zero resistance, so I don’t think it was a clogged nozzle.

Any idea what would cause this to happen and/or how to prevent it?

As a result of this issue, my bed was covered in a very thin layer of filament. I heated the bed to 100C and tried to scrap it off. Got most of it, but there are still some high spots that I can feel but can’t seem to scrape with my razor blade.

Any tips for cleaning the bed? Is there anything out there that’s safe for the bed and that will dissolve PLA?


Heat your bed to ~80-100C and get some isopropyl alcohol (I use 91%) and a towel. If you cant start a scape with the bed heated, use the towel with a generous amount of alcohol. I have done this with the bed cold and hot, just keep in mind alcohol is flammable so be careful when cleaning. As many forums will say, a glue stick or blue painters tape on the bed can help with removing the print from the bed, so it would be advised in the future before you start your prints, especially prints that take up a lot of the bed space.

Agreed. I give a quick wipe with alcohol before each and every print. Every filament can leave some kind of residue, not to mention any oils and such from your hands left from handling the bed in trying to remove prints. I use the same just regular old Iso alcohol, but in a sprayer so A) you use less and B) it’s easier to spread across the bed. A few “good” sprays and rub/wipe is down really well. If it’s hot it will start to evaporate quicker, so you may have to re-apply/spray again and be quick to actually remove things (i tend to spray it cold).

For embedded/tough things, I also use a flat blade (like for scraping gunk off of glass). You want to be VERY careful though if you go with this method as to not ding or scratch up the surface. Digging the nozzle into the bed face is kind of already doing that anyway, but still with a blade it’s very easy to get the angle wrong and slice up the bed, which would be bad. I start with it nearly as flat as I can and very gently see what might still be “raised” off of the bed.

i’ve heard of others using the nozzle itself to essentially “fake print” things without any filament in it, using the heat of the nozzle to re-melt the plastic. I wouldn’t advise that but just sharing information!

It sounds like your leveling is “too close” to the bed, so the first layer got “pushed in” too far, which can lead to scraping of the filament in the extruder (since it’s still trying to push filament through even if it actually can’t) as well as that first layer sticking TOO well. Some things you can try with that is:

  • Set your first layer height higher (assuming it was 100%, or whatever the equivalent of that is in whatever slicer you used). Setting it to 150% or 200% (or 1.5x or 2x of your layer height, again whatever your equiv setting is) will have your nozzle away from the bed farther but as long as your calibration is correct, should put out the correct amount of filament. If your calibration is too close though, then it should “push” the filament into the bed some, but since it’s higher, it should compensate for any small imperfections as well as allow filament to continually be extruded.

  • Re-calibrate, but on the last manual step, save it a touch higher than before. Also making sure to use as many points as available (assuming your bed is reasonably flat).

I’d start there and that should keep you going as you learn more about printing and such. What COULD have happened is it just being hard to push filament through to the point it stopped (since it both started fine AND you had a good amount of filament stuck to the bed). It would have been more OK if it was a small piece for the nozzle to be super close and filament to be “blocked” by the bed (not SUPER ok, just less damaging) but with a huge print and if that happened for that amount of time, I could see it clogging the thing (essentially).

If you haven’t already too, you also want to make sure you extruder is properly calibrated. Some of the better filaments like Hatchbox perform well enough that you can get away with not doing that (like i did for like a year) but it’s definitely something that you should do with every printer. Extruder Calibration a must

Sorry for the long post! it’s tough to speculate with not too much data/testing since there could be a variety of things that could stop the print mid-print. An example if if you just have crappy filament, which may have some “hard” impurities in them that don’t melt, and if large enough could clog the nozzle (if it’s small enough). that type of thing is fairly rare, but it’s still just one of those things that happens.

hope that helps!

@Phalynxx, @magumbasauce

Thanks! Great info. I cleaned the bed off successfully and am now going to mess with my Z and layer heights. I’ve been following the instructions in the manual in this regard, using the calibration card and lowering the nozzle until the card is harder to remove. To your point, I want to do a test with it set higher to see what difference that makes.

I also put my filament in a food dehydrator, as my basement RH is 60% or so and the filament has been out for a week.

Will try again tonight when the filament comes out and go from there.