A1 0.2 Nozzle Scratches the surface and changing Z offset doesnt help

[Graviret]

Heyo all, i´ve been trying to get my A1 to print with an 0.2 nozzle without issues for a while now, im at my third nozzle (the first two broke down from use and scrapping) and i started to see near the second nozzle last prints that it was sometimes scrapping at the bed.

At first i thought i had toe manually change the Z-offset, so i did, i noticed that i had to use a whopping 0.20 Z offset to get that nozzle to print, any other value and it either blobbed up or started scrapping against the prints/bed. That solution only lasted for a few weeks until it finally stopped working and if i went any higher on the Z-Offset the prints started to come out wrong (you could see the lines even on 0.06 quality).

So anyway i got a third one and decided to do things right this time, a store owner from where i buy filament told me that some A1s came with an issue that made 0.2 nozzles too close to the bed and that caused them to start wearing too fast. This time then i decided to check all the screws from the hotend (yes, the three black ones from the front and the 4 small ones from behind the nozzle) and started making prints at 0.18 Z just in case.

The results where…ok i guess, while most supportless prints came out great, the brim was…wispy? You could see the strands of filament when you took it out, but overall it seem OK. The problem started when i started making Miniatures with supports and oh my, it was blobs galore from that point forward. Almost lost another hotend assembly from a blob of death.

So anyway i kept tinkering until i saw…one print that had BOTH the issues of a low Z-offset value and a high one, meaning the first layer either got scrapped off the bed OR was weak and looked like it didnt bond correctly. At this point i really just gave up, how in the seven hells can i get BOTH problems back to back with the same Z-offset? Any ideas what can possibly be the problem?

Just in case:
Bed Temp: Textured PEI 65
Nozzle Temp: 220
Retraction: 0.4
Filament: Creality Hyper PLA (worked almost better than Bambu PLA)
Cleaned the bed, the gears, checked all screws.
Did a factory reset, checked all the screws just to be sure and recalibrated everything again.

EDIT: After some more tinkering, i stood besides the printer while it started, and i could see that the parts of the brim that where semi-transparent happened to be where the nozzle sounded like it was way to close to the bed and the extruder gear clicked, some pics for reference:

Right at the red marker i could hear the nozzle scrapping the bed, i wanted to upload a video but i cant upload mp4, but i have this pic of the model, right at the feet, when the nozzle does the either the outher or inner walls, you can actually hear it almost like its scratching the print, and it only happens at those parts and with every 0.2 nozzle i used, never with the 0.4

[Bullocks]

Sounds like the autocalibration is completing incorrectly, and mostly erring to be too low to the plate. There’s a large number of confounding factors - you mentioned screws, but just want to make sure you mean specifically the 3 + 4 black heaterblock screws, but you can also try doing a thorough Z screw cleaning.
Textured bed is also possibly not great with a 0.10mm initial layer - the depth of those grooves are around 0.05mm - shrink yourself down to an ant’s size and imagine how that goes, even on an exactly-precise Z.

[Graviret]

Thanks for the reply, yes i mean both the 3 screws from the front and the 4 from the back of the hotend, in case of the intitial layer, what config would you recommend? I dont really know if i should make it thinner (all the way down to 0.06) or try 0.14.

[Bullocks]

IMO smooth plate would be a good baseline, but if you stick with Textured, I would both raise the z offset by 0.05 of whatever it is there, its probably audibly scraping given that picture, and also increase the 1st layer line height to make those textures not such a large % of the size of the layer

[Graviret]

Im going to wait a bit before getting a Smooth Plate (as i cant spare the money now and where im from the parts are expensive), but do you suppose a Smooth plate wold work better with the 0.2 nozzle? Everything i do with 0.4 works almost perfectly, might have some adhesion problems with complicated models but 80% of the time it works perfectly, going to try increasing the 1st layer height to 0.14 and the z-offset to around 0.22-24 to see how it goes (at 0.20 it still sounded like the nozzle was scrapping against the model at later layers) mind you tho, i´ve had the same model scratch the bed at 0.20 z and at the same time after doing it again it didnt scratch the bed, which is what confuses me.

Oh and by the way, would you recommend the Supertack beds? Given the price difference i could try those, heard a few good things about them and they just started coming in at my country.

[user_4117187745]

Hello. I am experiencing problems with extrusion. The 0.4 hardened nozzle scrapes the textured PEI plate. It started about 1 week ago and I have contacted BL CS and they have so far only asked me to run a calibration test, bed tramming steps, checking the heating block screw (3+4) which I have done and whenever I’ve run the calibration test it does not throw up any errors. My A1 mini is JUST over 1 year old now and don’t expect I have any warranty on it now or chance of it being sent in to be fixed (or even know if this is a service they offer) Originally I was told by CS that this was due to moisture in the pla filament and purchased the Sunlu S2 filament dryer and dried it initially for 6hrs @ 50°c and didn’t notice and drop in the Rh levels so run again @ 40°c for a further 10hrs. Run a test print and the same thing happened. I changed filament brand and even opened new spools and dried before testing and the same happened. With BL CS taking so long to get back to me I’m wondering if anyone here has any suggestions on what they have experienced or had a resolution for the same issues?

[Graviret]

Well thats weird, of all the nozzles that i´ve used in 7k hours of printing (3 0.4 and 3 0.2), the 0.4 NEVER had any kind of scrapping issues. If you have another nozzle try changing it to see if the problem persists, in my case, only 0.2 nozzles scrape against the bed, while 0.4 work flawlessly, which makes me believe that the problem is in the nozzles and my settings rather than someplace else.

BUT if you dont have a spare nozzle to use, try doing what i did with the Z-offset configuration, i use Orca Slicer and its in the Printer Settings → Printable Space → Z-offset. It starts at 0.00 (as it should be, auto calibration should take care of that issue but oh well, its back to the ender 3v2s days lol) given that it is already scrapping the bed, try increasing b 0.05 or even 0.10 just to avoid potential damage to the nozzle, at worst you´l only waste a bit of filament as it doesnt get to stick in the bed.

[Bullocks]

Well, if you think about it, for your Z to very barely scrape at 0.1mm [initial layer height] means that running that same “tune” at 0.2mm means it probably is a little squished too [pushing 0.2mm of stuff into a 0.10 space, not impossible] but definitely would print. Less about your nozzle than it is the initial layer height that goes with the nozzle. If the thing’s absolutely off by 0.10 thats your entire layer in one scenario. This scenario

[user_4117187745]

I only have the 0.4 nozzles so unable to test 0.2. I’ve tried other 0.4 (2x) and the same happens. The test print was a playing card and the outer lines were perfect and the spades outline the same. The infill starts ok then about 15-20 lines across it grinds and sounds awful which is when I cancel the print. I’ve not adjusted any settings in the year I’ve owned the A1 mini and always followed the designers settings when printing. I just load the AMS lite and hit print. How can the z axis become offset?

[Renzei]

Hi. I’m also recently having the same problem which i cant figure out. Prior to this my prints were always fine but recently i’ve been noticing that there’s always rough extrusions and at times the nozzle grinds onto the plate as well. I’ve done calibrations, orienting the z-offset, even checking all the screws tightening and it’s still underextruding. What other advice can someone suggest to fix the issue?

[Graviret]

Well, tried to z-offset at .24 and the good news is that the nozzle didnt scratch the bed while making the brim (it did a bit when making the thin part of the flow calibration), the bad news is that it was so far from the bed that the brim didnt bind itself correctly and it was mostly strands that didnt stick to the plate at all and was already making a blob at layer 30. At this point i really, really dont know what to do, its either use 0.20, scratch the bed and nozzle so it wears out in 50-100 hours of use or go higher and not get anything done.

EDIT: Been trying to go even closer to the bed, still not scratching but the first layer wonth adhere, now at 0.08 and its amazing how from one day to the other the printer decides to act completely different with no reason whatsoever, before i could hear scratching noices at 0.18, now at 0.08 i cant hear nothing but get no adhesion (and no, i cleaned the bed like 3 days ago, not going to clean it AGAIN, it cant have gotten so dirty in such a little time).

[user_4117187745]

I’ve just finished fixing my A1 mini.

Here are the steps I took.

Spoke to BL CS they suggested doing the bed tramming steps and to download the gcode to the memory card and run the test calibration. Did that.

Removed the 3 screws from behind the nozzle and tightened the 4 screws on the reverse.

At this point I was still having issues with nozzle scraping badly.

Then, after looking through these forums, I noticed that the extruder unit could be at fault. So I ordered the extruder unit, new 0.4 hardened nozzle and a hot end cooling fan. They arrived 3hrs ago and it took me 1hr taking my time to make sure I took pictures of the disassembly for reference to make sure all screws went back to the correct part.

I then ran the machine on board calibration test and showed zero errors.

Then I ran a test print which was a ace of spades throwing card (quick and easy to make sure the nozzle was no longer scratchy against the bed) and it came out flawless.

To say I’m happy is an understatement.

Yes it cost me a week of back and forth with 1 message at a time to CS and a few hours research and an hour to fit the new parts at a cost of £49.97 delivered.

But it’s done. Was worried because it’s literally 2 weeks past the 1 year warranty and they told me any parts would be at my cost.

Hopefully this will help someone else and help relieve the stress it causes.

Any questions I’d be happy to share my experience with you.

Before and after

[user_4117187745]

Have a look at my recent post.

[Graviret]

yeah…while it would be wonderful to be able to do so (just buy brand new parts), im from Argentina, and the nozzle alone costs more than those 3 things together. Might be worth noting that my printer is already past the 7k hours print time and the only changes that i made where getting new nozzles (this one thats giving problems is brand new, started working badly at the third print) and the hotend assembly (as the cables got damaged by an old blob of death of mine…from my first 0.2 nozzle lol)

[user_4117187745]

Hi. Wow they are steep prices indeed. I did think about cutting my losses at quite a few points in the last week and just put the money towards a bigger Bambu Lab printer. But having researched so much about this A1 mini I’m going to stick with what I know. Fingers crossed for you my friend as I know the pain they can cause.

[Graviret]

EDITED: Woke up and tried to do another miniature, the nozzle was yet again dragging, lo and behold for some reason when i saved the changes in orca the configuration went back to Smooth Plate and it obviosuly didnt work, for now it seems that 0.08 z offset is working ok (changed it in the machine gcode).

Picture for reference, hte nozzle started dragging again just because orca decided that switching back to smooth plate after i saved the nozzle preset was a funny thing to do. Was nearly losing my mind thinking that turning off/on the printer and one night of sleep could make all that effort go to waste jajajaj.