Low quality low layers (but not first layer)  

RE: Low quality low layers (but not first layer)

It's from the radii on the corners.  They are an extreme overhang on the bed.  If you change them to 45 degree chamfers it will produce a much better result. 

You should be able to see this if in the sliced view if you scroll down to the first few layers 

RE: Low quality low layers (but not first layer)

Thanks for the advice Brian. I tried it with chamfers instead of fillets, but got essentially the same results.

I'm going to try again with adjusting/adding more supports. Any other ideas?

I'm also getting a new odd wrinkle... The top layer is showing as internal perimeters and infill instead of external perimeters. It shouldn't really affect things for this print, but it is weird.

RE:

@brian-12 is basically right - plus, snug supports would serve you better here.

If you want more specific help save your project as a .3mf file

Files > Save Project as

Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.

Cheerio,

RE: Low quality low layers (but not first layer)

@Diem. Here's a zip file of the 3mf. Would really appreciate it if you have any ideas?

Zip of .3mf:

Joint with ugly low layers

RE: Low quality low layers (but not first layer)

Have you tried with the default settings?  That's what I created in the attached 3mf.  There was lots of stuff modified in the print settings and some things in the printer profile.  I've had really good luck with the default settings.  I left your infill, and perimeters, and switched to the Prusament Filament Profile (I find usually that these work well in most cases) and only put support material on that center overhang.  I didn't print it, but I don't see anything jumping out to me on the sliced file when setup this way.  If you still don't have success I can try printing it tonight.

RE: Low quality low layers (but not first layer)

I'm printing it now on my old Mk3 which will take about 3h and on my sv08 which will be done in about 40m.  
Initial thoughts, don't use arachne.  You have thin edges on the holes and hexagonal parts, arachne doesn't like though so is slicing them incorrectly.  Swap to classic, or if you do want to use arachne then adjust the settings till it picks up the edges.

You are using way too much support, the only bit that needs it is the middle. I suspect its all down to cooling and layer times.  Which is why those lower layers that are short and also closer to the bed with its heat are deforming while the upper layers are not.  

RE: Low quality low layers (but not first layer)

@brian - I have been tweaking "my" settings little by little here and there for years as needed - Testing a refresh back to default settings is a great idea!

@Neophyl - Thanks so much for doing a test print (or 2!)! I can do a test with classic later tonight for an apples to apples comparison on my same printer (I've got a different 6 hr print going now). FYI, I did start with less support and added it when these issues showed up (but it does seem by now clear that lack of support was not the issue).

RE: Low quality low layers (but not first layer)

Ok the print on the sovol sv08 is done.  The Mk3 one wont be done till the morning so I'll post after I get up.

Please keep in mind that I only bought the SV08 just before Christmas and I am still dialling it in.  Also the smooth sheet fitted I've only been using from today  so my first layer needs some work lol.  Need to add a bit of a brim gap I think as the brim was well and truly fused to the part.

This was printed at around 100-150mm/s speeds (outer perimeters at 100, inner perimeters at 150 so I don't think its too bad.

So there is some roughness on those steep overhangs near the bed but I also don't think those areas are that bad.  The holes are about what I would expect.  

I'm now curious as to what the Mk3 part will come out like.  My MK3 is an old MK3, not even an S but it has had a 3:1 geared extruder fitted and has an upgraded part fan cooling solution 

RE:

I had a spool that only had a super small amount of PETG on it that I'd been wanting to use up so I printed what I could until the spool ran out. 

The part turned out ok, definitely better then your example.  That being said the super thin sections and the odd angle that gets created by how it's orientated on the print bed makes for some less than ideal printing paths.  The sections that come to a point would benefit from a minimum 1.2mm flat. I think they would print cleaner.   I've found that when you have single path overhangs that go to a point they didn't usually print very well.  See below. 

That being said what printed was most likely usable but I think if you change your model as I've suggested it'll likely print much nicer. 

RE: Low quality low layers (but not first layer)

I'd agree with Brian.  I think those pointed sections are curling up during printing, due to the cooling and then the nozzle is hitting them on the next layer.  Which is leading to the deformed areas.

Normally I don't use brims as they are generally not needed but I had to with this part as the first attempt caused a crash and was knocked off.  I ended up actually turning the cooling down.

RE: Low quality low layers (but not first layer)

I think those pointed sections are curling up during printing, due to the cooling and then the nozzle is hitting them on the next layer.  Which is leading to the deformed areas.

That's the best I've ever heard that explained.  That's exactly what happens.

Not much point in trial-printing now, @neophyl has explored the area I was thinking about.

I presume this is a replacement for a part originally made by injection moulding, it's not well designed for 3D printing.  If you do not expect high stresses you might seperate the flattened hexagonal parts and turn them into inserts.

If starting from scratch I would attempt to eliminate those little centering steps.

Cheerio,

RE: Low quality low layers (but not first layer)

Thanks so much for all the updates and help!

My print from last night (with reverting to mostly default settings) did come out noticeably better.

It did fail early on in my first try, so I watched it for the first layers on a 2nd try and saw the one corner curling up.

I am going to tweak my fan/cooling settings and give it another try and see if I can continue to improve it.

I also added an additional chamfer to the model to eliminate that single path overhang that @brian pointed out (it's now 2 paths 🙂 ).

@Diem - FYI, You are correct that it is a replacement for a injection molded part (or really a modification to the existing part to tweak the functionality). I definitely do expect high stresses, so trying to keep as much strength as possible. I did print some flat earlier, which is an option, but leads to long sections of bridges at the top of the internal hexagons that are not ideal.