Terrible print quality suddenly on A1

[John18]

I’ve got an A1 printer that’s been working fine for a year or two. Then last week it suddenly messed up a print (object not attached to bed, but hanging off printhead). There was an error about the hotend fan, but that disappeared. Now it won’t print properly - the first layer is really rough, then it tends to peel away after a few layers and it ends up printing in mid air…

I’m just trying to print the built in bed scraper tool during testing, as that’s a known quantity. Regular bambulabs light grey filament, printing the tool from the printer display, default settings.

Because of the error I replaced the hotend fan. No change. I thought maybe the printhead was partially clogged and had a new one sat around so I replaced that. no change. I went through the Bambulabs troubleshooting guide and it kind of looked like maybe the “printhead too close to the bed” issue, so I did the auto bed levelling. no change.

When loading the filament, and also in other phases where the filament is ejected, it looks “normal”. ie. it just poops out the filament smoothly.

This is the “pre-print” from another A1 printer, and shows what the normal pre-print looks like.

This is the pre-print from the faulty printer -

And this is the first layer or two of the scraper tool -

As you can see it looks very rough.

So, to recap - worked fine, then terrible print quality, the new hotend fan, the new hotend, then auto bed levelled, still terrible print quality.

Any ideas what the problem is, or next steps?

[shane1234c]

you need to tighten the hotend assembly. the 4 screws behind the nozzle came loose, so when it does calibration it is measuring the nozzle fully up, but when printing, the extruder is pushing filament so your nozzle gets pushed closer to the bed, creating this issue of minimal layer height. Take out the nozzle, loosen the 3 screws on the nozzle plate, slowly pull the nozzle plate away from the machine enough to reach the 4 screws on the backside of the plate, retighten those and assemble, calibrate and print successfully.

[Bullocks]

Your machine looks like its autocalibrating too low-to-the-plate.

Hotend tightening is my first suggestion as well. If the hotend 4-screws-then-recalibrate doesn’t fix it, do a thorough Z rod clean+regrease, especially down low where the gantry rests at z=0. Make sure that during the calibration’s bed level, the nozzle tip is clean of errant plastic.

[John18]

Thanks, this worked. Weirdly the printhead didn’t seem loose or wobbly, but all 4 screws were indeed loose and tightening them does seem to have fixed the problem!

[shane1234c]

No problem. Not too much gets past me on the a series, I keep mine humming… this photo is from a month ago, just crossed 14,300…