Slicing works in Arachne mode, but fails in Classic.
Dear community,
The attached project is sliced sort of with arachne perimeter generator (see comment below) and fails with classic (only 2 layers are sliced):
In arachne mode the generated wall width is 0.8mm instead of request 1.2mm 😥
The flow rate seems to be within the limits.
Prusa Slicer v2.7.2 (the issue was first detected in v2.6.0).
Thanks for any advice.
Best Answer by Neophyl:
Of course it doesn't slice. You have your extrusion widths set to 1.2mm for everything except the 1st layer where its 1mm. The wall thickness of your part is on average around 0.5mm thick. With Classic mode features smaller than your configured extrusion width are ignored as they aren't printable with the configured values.
So you have instructed the slicer to slice using an extrusion width of 1.2mm but the walls are less than half that width, therefore its not printable. The lower layers are there as the curve at the bottom makes the slice wider than the extrusion width. As it moves upwards though its basically at your parts wall thickness.
If you want to slice this part then your extrusion width needs to be set at a value either the same as your wall thickness or less.
Arachne tries to reduce the extrusion thickness (ignoring the set extrusion width values configured in Print Settings>Advanced>Extrusion width and using tis own settings. As your arachne settings are set to a minimum feature size of 25% and your extrusion width is 1.2mm then that means it will 'pick up' any feature larger than 0.3mm (1.2*0.25) so your wall thickness of 0.5 is printed. Or at least it will attempt to.
Printing extrusions thinner than your nozzle diameter is problematic and not generally recommended. It looks like this object is designed to be printed with a 0.4mm nozzle.
Just because you set an extrusion width it doesnt mean it will oversize your parts. The slicer will try but there are limits.
RE:
Of course it doesn't slice. You have your extrusion widths set to 1.2mm for everything except the 1st layer where its 1mm. The wall thickness of your part is on average around 0.5mm thick. With Classic mode features smaller than your configured extrusion width are ignored as they aren't printable with the configured values.
So you have instructed the slicer to slice using an extrusion width of 1.2mm but the walls are less than half that width, therefore its not printable. The lower layers are there as the curve at the bottom makes the slice wider than the extrusion width. As it moves upwards though its basically at your parts wall thickness.
If you want to slice this part then your extrusion width needs to be set at a value either the same as your wall thickness or less.
Arachne tries to reduce the extrusion thickness (ignoring the set extrusion width values configured in Print Settings>Advanced>Extrusion width and using tis own settings. As your arachne settings are set to a minimum feature size of 25% and your extrusion width is 1.2mm then that means it will 'pick up' any feature larger than 0.3mm (1.2*0.25) so your wall thickness of 0.5 is printed. Or at least it will attempt to.
Printing extrusions thinner than your nozzle diameter is problematic and not generally recommended. It looks like this object is designed to be printed with a 0.4mm nozzle.
Just because you set an extrusion width it doesnt mean it will oversize your parts. The slicer will try but there are limits.
RE: Slicing works in Arachne mode, but fails in Classic.
Thanks!
I think Prusa could issue a warning that the model is not sliced because walls are much thinner than the nozzle.
Could you suggest how to print this model with thick walls? 1mm at least... Thanks in advance!
RE: Slicing works in Arachne mode, but fails in Classic.
There’s a setting that allows you to adjust the models xy size for each layer. On average you need another 0.7mm thickness to adding a positive 0.35 xy compensation is where I would start. This is both inwards and outwards so the models insides will be smaller while the outside will be larger. Be aware of that as its not just grown in one direction. It also doesn’t do anything to z as it each layer as it’s sliced. If there’s parts missing then slowly add a bit more until it’s all sliced.
Of course the best way is to adjust the model in cad. That way you can control the wall thickness and the direction that the thickness is added.