Multiple fails on self designed model

[TheDepsDoodles]

Hi folks,

It’ll be hard to give all the details as recommended as this has failed several times in several different ways so I don’t know if anyone can help, but I hope so.

I’ve been using the A1 Mini, Sunlu PLA+ white filament, using the bambu pla settings as i’d read that they are close enough to each other and usually get good results & on models printed from makerworld it has worked fine, but on my own I keep having issues.

The settings i’ve changed from default on my most recent attempt are;

quality;
Layer height - 0.1mm
Ironing type - top surfaces
only one wall on first layer

strength;
wall loops - 3
sparse infill pattern - adaptive cubic

speed;
initial layer - 35 mm/s
initial layer infill - 85mm/s
outer wall - 180 mm/s

Supports;
standard tree supports

others;
fuzzy skin - contour
point distance - 0.2 mm
thickness - 0.2mm

I’ve been trying to print what I thought was a very simple model for over a week now, i’ve had a couple of decent results but never 100% and i’d say i’ve had more total fails than completed prints.

This is the model pretty much as it should be;

The only issue I had there was bad overhang;

Which I tried several things to fix & now have much improved just by slightly changing the model so it’s not quite as steep an angle.

The most persistent problem i’ve had is this;

The model prints up to this height & then one of the wings/ arms comes loose of the support & the whole print is over. Weirdly this only seems to happen when I try printing without fuzzy skin, so far anyway. I’ve tried various things to fix this & finally moved the printer off my wobbly standing desk on to an mdf sheet on the floor which still didn’t work so I don’t think it’s a vibration problem.

Anyway I’ve now put in some supports built in to the model (thin rods from the legs & body to the wings) and i’m hoping that will fix that, not ideal though as it adds more cleanup. Unfortunately I don’t know if it has worked as I tried printing yesterday with fuzzy skin again & it worked almost all the way to the end before;

Some massive layer shift occurred & again ruined the whole thing.

I just don’t understand what could be happening. I’ve never had a fail with a makerworld model so it must be something with my model, but with so many different types of fails & some actual successes, it’s just really mind boggling & frustrating, it’s cool to print other peoples models but it’s not what I wanted the printer for so i’m pretty desperate to get some consistency here.

Anyway, sorry for the long ramble, hopefully someone can help, if you need more details please let me know

[MZip]

May not be the root problem but your infill crosses itself which causes bumps as the nozzle hits the high points. If you switch to an infill pattern like gyroid it won’t cross itself and try to break loose.

Maybe a few more degrees of heat on the build plate would help? Filament seems to stick better as temperature on the build plate is increased.

Maybe slow down the print some? The bed slingers can put some loads on the bond to the build plate as the model gets slung around with the bed?

[TheDepsDoodles]

Thanks I think I have tried Gyroid at one point, can’t recall if that was a successful one or not though presumably that’s a suggestion to stop the parts coming loose?

The build plate is pretty much always 220c, I’ve never manually adjusted it, but nothing actually comes off the plate, the supports stay in place & the parts come out if the supports, it’s bizarre

Slowing down the bed is definitely on my list of things to try though

So are all of your suggestions related to the parts coming loose? Or could those things cause the layer shift too? That one really has me baffled

[MZip]

Yep. Gyroid is much easier on the print since it doesn’t cross itself. Infill that crosses makes tall objects with lots of leverage try to break free.

Good point about it not coming loose from the build plate but still bet gyroid would help.

I was thinking about parts coming loose but layer shifts may also have something to do with that. Layer shifts are kind of a mystery to me. These printers home and then just count after that so they can layer shift if something causes a stepper to not be able to step like a jam or something shifting the print bed. I’ve never had a print shift like that (X1C) to be much help on that.

[TheDepsDoodles]

Thanks again, that’s useful info about the difference between infills anyway even if it doesn’t solve everything

I’m hoping the shift is a fluke or something but we’ll see.

I’m gonna try it again anyway without fuzzy skin & with Gyroid & see how it goes, right now I’m printing a similar size & print time model off makerworld as I realised everything I’ve done from there takes 1 hour at most whereas my model is taking 3+ so it’s hard to compare maybe if this works I can steal the settings & apply them to my model

[Contributing_Factor]

Besides switching to gyroid infill, I would also either make the feet flatter, or enable a 1cm brim… or both. Looks like only a small part of the heel and footpad make contact with the plate, and supports are not a strong enough base for a tall model like this. Any small contact between the head and the print would cause a failure.

[TheDepsDoodles]

Thanks yeah the feet have been a problem, but I really like the shape so wanted to keep it that way if possible, after all feet aren’t flat, I mean they don’t only have four toes either but hey ho

So a 1cm brim, I’ve tried printing it on a base before but again it broke off, might a brim be different?

I also tried printing it on it’s back before to preserve the feet & this absolute horror show occurred;

I had thought it’d be much better to print it this way but, not this time

[Contributing_Factor]

Part of designing for 3d printing is to accept the fact you’ll have to compromise somewhere. The feet are largely supported by two tiny areas and tree supports (which are designed to separate from the model… so they won’t help adhesion much).

You can flatten the feet
Or
You can cut the model in half (top and bottom) and put the flat area of both parts on the bed and glue the two halves (add a belt to the model to hide the seam line?)
Or
You can reorient on the back, print with supports and accept that the surface on the back, back of the arms and legs will be rough.

If you want to try cutting the model, bambu studio can do that for you using the cut tool.

[buddy1]

(post deleted by author)

[buddy1]

You can try starting by improving the supports, switch from tree supports to standard supports with increased density and enable interface layers for better adhesion, especially under the wings or arms where failures occur. Check your model in a tool like Meshmixer or Netfabb to ensure it’s manifold and doesn’t have internal geometry issues that could confuse the slicer.

[TheDepsDoodles]

Yeah I appreciate that & am grateful for the advise, I’m just an idealist & a perfectionist unfortunately they don’t line up well with reality

I have considered printing in two halves, if I could achieve a nice finish with paint rather than the fuzzy skin then I could maybe hide the seam, but i don’t know if that would be possible, something else to try anyway

[TheDepsDoodles]

Thanks I have never tried non tree supports, they always look like they’d be a nightmare to remove but I’m willing to give it a try, I’ll look into interface layers too.

There are definitely non manifold edges, but I hadn’t really worried about it as Bambu slicer says it repairs them, but yeah I had considered do a full retopo to make sure it’s clean, maybe Bambu’s repairs aren’t too reliable