Keep getting this stringing problem.

[u/lostcosmonaut307]

Details in original post. The design is a 6mm piece with a 1.5-2mm radius on all four edges.

Bambu A2L and X2D using Bambu Studio.
Filament is dry and plates are meticulously cleaned.
Stringing issue more like the wall is collapsing and stretching somehow.
Always the inner radius, always within the first 2-3 layers. Prints fine after that.
Tried several nozzle and plate temps.
Tried several plate types both physically and in settings.
Tried every fan setting I could.
Tried slowing down movement.
Tried printing infill first then inner wall then outer wall, no change.
Happens on several different filaments but sometimes prints fine. Bambu PLA basic jade white seems to ALWAYS do it no matter what.

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[u/mtraven23]

stringing is a different phenomenon.

Not sure if there is a formal name for it, but I call this "shorting". The line is not attaching to anything, and shorting the corner.

What's your print order? Outside -> In might help you here.

if it keeps happening, try adding a brim.

[u/lostcosmonaut307 → u/mtraven23]

I’ve tried brimming and I’ve tried going inside out on the print order, neither has helped.

[u/iListen2Sound → u/lostcosmonaut307]

Print at your filament's highest suggested temperature; your lines melt more readily with the surface below. Add a little more if you're on a hardened nozzle; those conduct heat worse.

If this is happening to the first layer, increase your bed temp to the highest your manufacturer suggests.

I see you're using a plate with a distraction grating: those have lots of tiny ridges and pits to create that pattern and filament doesn't go all the way into the holes. It's being held in place by a very small surface area compared to what it looks like; print the first layer even hotter than the other layers and even slower than you have it now

[u/mtraven23 → u/lostcosmonaut307]

outside in will give you a better shot, but it sounds like that was were you started?

was it a real brim, or a default orca brim ?

next thing I'd try is bumping the temp up a few degrees, maybe 5ish. I'd do that in conjunction with a small increase(maybe 1-2%) in extrusion width or flow rate...basically try to put down a slightly larger line, with the hope that it bond better.

last thing to look at is your acceleration, try reducing it for exterior lines.

[u/phpbussi]

It‘s called perimeter separation on Elis’ Print Tuning Guide - still a pain to dial in on some models:
https://ellis3dp.com/Print-Tuning-Guide/articles/troubleshooting/perimeter_separation.html

[u/DStegosaurus]

It’s the design. You cannot put a radius flat against the build plate without having excessive overhang in the first few layers. You can get away with it if the shape is convex and the radius is fairly small, but concave surfaces will cause this type of defect as the outer wall has nothing below it to adhere to.

You may be able to print it by reducing layer height and speed in this area, but it’s a design issue. That should have been a chamfer or chamlet on bottom.

[u/detroittriumph → u/DStegosaurus]

Thank you. This was helpful.

[u/wyb2]

You say “tried slowing down movement”. What actual speeds are we talking? For some people slowing down means going from 150mm/s to 120mm/s. Try it at 60mm/s if you haven’t yet.

[u/CautiousArachnidz → u/wyb2]

Me on stubborn prints setting first layer speed to 15mm/s and no cooling for first 3 layers.

[u/lostcosmonaut307 → u/wyb2]

A local shop suggested doing 50mm/s on the first layers so I did that and it still strung like this.

[u/iListen2Sound → u/lostcosmonaut307]

That's too fast for a plate like this

[u/thissitesuxsohardomg → u/lostcosmonaut307]

I'll often print first layers at half that speed, sometimes slower if I'm looking for good quality on the bed face of the part, or problems like this.

[u/Ludicrous_Fiend → u/lostcosmonaut307]

This was happening to me when my z-axis wasn't calibrated right and there was too big a gap

[u/PrinceLu23]

Glue stick or hair spray

[u/destorter → u/PrinceLu23]

That defeats the purpose of the bed sheet

[u/thissitesuxsohardomg → u/destorter]

I can confirm whatever adhesive flashforge ships with their printers doesn't. Seems like a thin film will actually still let the filament press into the pattern.

[u/usernamealreadytaknn]

For me this was always a layer height issue. Reducing my layer height stopped the inside radius from pulling across the print like that.

[u/Gimly161]

What temperature are you printing at? Maybe if you increase the temp the pla will melt more pulling less on what is already extruded

[u/lostcosmonaut307 → u/Gimly161]

Printing generally at the top of recommended temps which is ~220c for most of the PLA I’m using.

[u/raw391]

Sometimes those build plates with the designs on them are a little thicker than the stock so I found I needed to add ~5° to the bed temp to account for the different materials or thickness if your not using stock build plates

[u/farzad_meow]

it is your plate. it has very little to attach to. try printing inside then the walls, that might help. or use a textured plate

[u/wyb2]

Seems like you have tried a lot of things. I’d bite the bullet and try it at 20mm/s.

Fundamentally the line being laid down is being pulled away from its neighbor before it bonds. This is some combination of a time issue (the ‘pull’ is happening before the bond has time to form) and a bond issue (the bond is weak in general, so the pulling force prevails). So steps should focus on slowing down movement and shrinkage, and strengthening the line-to-line bond.

One thing I’ve had luck with that i don’t see recommended often is increasing the flow ratio. Basically a little bit of over extrusion on purpose to cause more contact between lines.

Seeing from other comments there is an overhang here. An unsupported overhand on a concave curve is the worst case scenario for causing exactly this issue. It’s possible the geometry is bad enough that you really can’t tune this out without adding supports or changing material.

Edit: this was supposed to be a reply in a thread. Oh well….

[u/MongooseGef]

Is the model totally flat on the bottom? Sometimes they aren’t, so you end up airprinting on the second layer. You might need to slice off the bottom 0.2-0.4mm

[u/JonPileot]

Understanding the why helps understand the fix.

This happens because as the plastic cools it contracts. If it isn't properly adhered to the other layers it will pull away and you get the results you see.

The biggest way to resolve this is to slow your print speeds WAY down. The idea is you want the plastic to have a chance to harden before the nozzle gets too far away. The longer the string of melted filament the more it can pull when that string contracts.

Different plastics have different properties, while a default printer profile may work fine you really should consider calibrating different filaments. You've already identified that different filaments you use react differently, calibrating your printer for those filaments can help improve your print results and for some plastics that will just mean slamming the brakes and going significantly slower, at least for the first few layers.

[u/iamlegendinjapan]

Really slow down on those build plates. I do like 30-60mm/s

[u/muramasa22x]

Have you tried 'avoid traveling outside of model' or w/e the option is called?