this is not a basket - first layer looks like woven  

RE: this is not a basket - first layer looks like woven

Maybe there's something else going on but I'd first try to better adjust live z. This looks too low but I always find it hard to gauge from a photo. With something like this https://www.prusaprinters.org/prints/105404 you can try a few values for live z in one print and do a comparison. 

RE: this is not a basket - first layer looks like woven

@hawai

You have been printing, and active here for awhile now, I'm betting you know what a first layer should look like, have you checked the Bondtech gears to make sure they are seated properly and grub screws tight. Also, is the new hotend an E3D V6, or other? That first layer gives the appearance of being to close, however it looks so rhythmic in the image I'm thinking it's a drive issue.

Regards

Swiss_Cheese

RE: this is not a basket - first layer looks like woven

I concur, that regular wavy pattern looks more than just a run of the mill live z issue.

RE: this is not a basket - first layer looks like woven

First of all I didn't stop the print because the aesthetics of the part weren't relevant and it came out acceptable. As it is a box with only a few layers bottom the pattern is visible looking at it against the light and the surface feels exactly as if z is too low.

A freshly printed Jeff Jordan square was off by 0.02 mm at most. So off to grub screw checking it is. I might have wiggled everything a bit too much when installing the new hotend, which btw is just the standard issue from Prusa, nothing fancy. I had a broken thermistor cable and the screw was coated in too much plastic so I swapped the complete hotend giving me time to restore the previous one.

Thanks for the help guys, I'll report the outcome of the grub screwing.

Cheers

Hansjoerg

RE: this is not a basket - first layer looks like woven

grub screwing

🙂

RE: this is not a basket - first layer looks like woven

Right?, Bevis and Butt-head would have had a blast with that one.

RE: this is not a basket - first layer looks like woven

More weirdness going on...

The gear is still aligned nicely, the grub screw is nice and tight.

Two additional things happened:

The IR sensor started to play up, but I have over tightened the screw that attaches the extruder motor to the carriage when swapping out the hotend. So this working again.

The next thing is that there seems to be under extruding or at least occasional underextruding with the filament that started the whole issue. See attached image:

Didn't happen with Prusament PLA, just with the yellow Kiwi3D brand. The yellow has been dried multiple times and has printed nicely most of the time.

So big question: continue to chase the problem or just chuck the yellow spool in the bin?

And question two in this context, is it considered normal that you have to spend significant time rejigging everything every 50-100 printing hours? If so how do people cope that run these machines for professional purposes?

Cheers

Hansjoerg

RE:

I don't know...this new picture looks like a nozzle digging into the filament, i.e., live Z way too negative. I'd redo my Live Z calibration before tossing the filament. I don't quite see how your calibration square can look decent on the one hand and then on the other hand you end up with these grooves in an actual print. [insert puzzled emoji here].

Re: rejigging everything every 50-100 printing hours, I guess it depends on your definition of "everything" 🙂

Stuff like Live Z may have to be recalibrated every time you swap a nozzle, and even some filaments like it a bit more or a bit less negative. Major maintenance shouldn't be required that frequently. I sell prints as a hobby, not to make a living of it, so I don't claim I can speak to "professional purposes", but I give my machines a look-over every month or so, clean things with compressed air, tighten screws. relubricate the axes, etc.

RE: this is not a basket - first layer looks like woven

Thanks fuchsr, good food for thought re too negative z.

I do indeed have different z's for different filaments myself, so good confirmation that I am not overly paranoid 🙂

What really confuses me here is that with about 0.08mm higher z the individual strands came apart on their own (not even needing pulling), hence I lowered the nozzle. I'll do a few more squares and see where it ends up.

RE: this is not a basket - first layer looks like woven

Update:

It seems to have been mostly the filament and probably not only the individual spool but likely the brand.

Redoing the z-adjust resulted in ever increasing extrusion gaps with the initial spool. Opening a still sealed spool of the same brand yielded  similar, but slightly less pronounced results. It also becam rather stringy, so I listened closely during the print and lo and behold, there was the crack, pop and hiss of wet filament 🙁

I still have no idea how the woven pattern happened in the first place but at least I now know I didn't kill the printer.

Cheers

Hansjoerg