Cura calculating wrong number of layers

[Jpileggi 0]

I am running Cura version 5.1.0. When I slice a Fusion 360 model with the dynamic quality (0.2 initial layer height, 0.16 layer height) profile selected, I get 19 layers for a model thickness of 3.81 mm. So 0.2 + 18 layers x 0.16 = 3.08 mm, or 0.73 mm short. I should be getting at least 22 layers. But if I slice with super, standard, or low quality profiles, I get the correct number of layers. Any thoughts? Is this a bug that has been fixed in subsequent releases? Thanks.

[Slashee_the_Cow 274]

Hiya!

 

I don't know if this is an issue that's been fixed in a newer version, if you could provide the .3mf file (File > Save Project in Cura) then we could have a look at it try to figure it out.

[Jpileggi 0]

Here you go. FYI, standard quality 0.20 and dynamic quality 0.16 profiles both give me 19 layers for the 3.81 mm dimension.

Depth Gauge Rail Ht Attachment.3mf

[Slashee_the_Cow 274]

Are you sure the dimensions are exact on your model, and when it's being exported? Here's an orthographic view of the side at 0.16mm layer height at layer 20:

And here's layer 20 at 0.2mm:

 

The grey areas represent parts of the original mesh which aren't printed (or in the case of the sides, not yet). In both of them, there isn't a layer's height worth left to fill. Although I do agree with you that it works fine on 0.12mm:

and 0.28mm:

 

Any chance you can upload the STL file so I can see if there's anything about that that looks funky?

[Jpileggi 0]

Here's the STL. I work in inches so the height in the model is .150" (3.81 mm).

Depth Gauge Rail Ht Attachment.stl

[Slashee_the_Cow 274]

TL;DR: The problem is probably adaptive layer height and your part would get printed at the right size anyway. It's automatically enabled in the 0.16mm profile and I'm not sure it's getting reset if you switch between the default quality profiles. Try going to Experimental > Use Adaptive Layers, turn it on, slice, turn it off again, slice, see if results are as expected. When slicing using my own custom quality profile, it never came up, so that's something you might want to consider.

 

Here's the results I get slicing the STL in 5.5 beta 1:

0.2mm - 19 layers (.2 * 19 = 3.8)

0.2mm, 0.3mm initial layer - 19 layers (.2 * 18 + .3 = 3.9, which is closer to 3.81 than 3.7 is hence that height)

0.28mm - 14 layers (.28 * 14 = 3.92)

0.32mm - 12 layers (.32 * 12 = 3.84)

I could try bigger, but I'm not sure my 0.4mm nozzle can print much thicker so let's go down:

0.16mm - 24 layers (.16 * 24 = 3.84)

0.16mm, initial layer 0.3mm - 23 layers (.16 * 22 + .3 = 3.82)

0.12mm - 31 layers (.12 * 31 = 3.72)

.12mm, .3mm initial layer - 30 layers (.12 * 29 + .3 = 3.78)

 

So that all seems completely normal (here comes the "but"):

BUT those were all sliced using my profile for my E3V3SE. When I switch to the stock profile for the E3 / E3V2:

.16mm layers, .3mm initial layer - 18 layers (.16 * 17 + .3 = 3.04)

.2mm layers - 17 layers (.2 * 17 = 3.4)

 

Experiments so far make me think that it's a printer definition problem - even though I don't know how that could possibly happen.

 

BUT then I realised it had switched to a stock quality preset - switch it back to my custom one:

.2mm layers - 19 layers (.2 * 19 = 3.8)

 

So then what the heck is different between the stock profile and mine that might affect it? I don't actually have that many settings customised:

What sticks out? Nothing, really. Top/bottom thickness only affects how many layers are printed as skin, not the dimensions of the object. Oh well, switch back to the stock profile to test the changes in my profile individually:

WTF?!? Now it's doing 19 0.2mm layers - the right number. Let's set it to the profile for 0.16mm and see what happens:

19 layers (.16 * 18 + .2 = 3.08) - what the hell? Switched it back to the standard quality profile. Still doing 19 layers. Good. So why don't I just turn down the layer height on the standard profile?

24 layers (.16 * 23 + .2 = 3.88). WHAT THE FAMOUSLY FABULOUS FREEFLYING FRUITCAKE IS GOING ON HERE?!?!!?!?!!?!!?? I mean, the stock quality profiles aren't that different to each other, are they?

Hang on a second. Adaptive layers? They make thicker layers where detail isn't required and thinner layers where it is. Switch to dynamic quality. Go into Experimental and turn off adaptive layers.

24 layers? That's... absolutely correct! THEN WHY THE HELL DIDN'T YOU DO 0.2mm RIGHT THE FIRST TIME YOU ^$#@e:@ING !@$#$%#@>?:#$lEST %%^$%><&)(_$@#THING?

It worked fine at 0.12mm from the beginning, lets look at its profile:

No adaptive layers here. How about you, 0.28mm?

No adaptive layers here either. Although I don't recall changing the defaults so that the initial layer height is that low for every profile.

 

SO BASICALLY... it seems like the problem is adaptive layers. And them leaking into other profiles somehow? If it's using adaptive layers, your part should still be the right size, some of the layers will just be thicker.

 

CALL TO ACTION: Try turning Experimental > Use Adaptive Layers on in whatever profile you're using, slice it, then turn it off and slice it again.

[Jpileggi 0]

Bingo, that's it!. If I turn adaptive layers off in the dynamic profile, it shows 24 layers (3.88 mm). If I turn it back, I'm back to 19 layers. So why is adaptive layers on as a default for the dynamic profile, but not for the others? That is really annoying - I had no idea.

 

Also, my part is actually coming out small on the .150" portion (.139" actual), but the overall height of the part is correct.

 

Hey, thanks for the ton of work that you put into this! Great detective work!