How do YOU pick wall thickness on your designs?

[jimustanguitar]

I'm drawing away on this multicopter project, and I reached a point that's made me wonder before - and I'm sure I'm not the only one who's thought about it... If you have a part in a model that only needs to be a thin wall, what dimension do you choose?

Do you pick a "go-to" number that sounds right? Like whole millimeters, 1mm or 2mm for example.
    OR
Have you ever considered making the wall thickness a multiple of your printer's nozzle diameter? Like making it 2 or 3 perimeters thick on purpose? (like .8mm or .12mm for a .4mm nozzle)



Am I nuts for worrying about this, or have you guys thought about it too?

[BeeAmaker]

I think you have to consider that each perimeter is going to be the thickness of your nozzle. If you have a section of your model that is only 1.3mm wide, there is no way you can print it with a 0.5mm nozzle without over lapping. 1.3mm / 0.5mm = 2.6 perimeters. The other 0.4mm of plastic has to go someplace.

So if I am drawing something thin wall it is going to be in multiples of 0.5. It slices a lot nicer too.

[bvandiepenbos]

I agree with Glenn, almost... I would draw thin wall areas a multiple of your EXTRUSION width (not necessarily the same as your nozzle size) as specified in your slicing setup.
In Slic3r I always set a specific extrusion width, like .4 for a .35 nozzle J-Head,
or .6 for a .5 nozzle SeeMe head.
The E3D has a .4 nozzle so maybe .45,
The Prometheus .4 nozzle works well at .44 extrusion width.
So the thin wall section really depends on your extrusion width.
By the way, if you let Slic3r "auto" calculate width by entering 0 it calcs a very wide width. You can fine the width by looking in generated gcode, it lists extrusion width.
Keep in mind that walls "3X" the extrusion width does not normally slice well in Slic3r, you probably will get only 2 walls with a void between where you would expect a 3rd line.
Cura handles thin walls much better... it actually makes 3 lines in the thin areas.

Cura is different, you can not specify extrusion width you only enter nozzle size, so I would use that for determining wall thickness.

so, yes Jim, I HAVE thought a lot about wall thickness & extrusion widths. Your not crazy (maybe a bit obsessive, but that's a good thing, right?)

[jimustanguitar]

Good point about extrusion width being different than nozzle diameter... Nozzle plus 10% is considered an achievable minimum width, I believe.

[jimustanguitar]

So here's another twist to this same train of thought...

What resolution do you export your STL's at? I've been setting the output to create facets where there's deviation of .2mm (same as my layer height). It seems more precise to set this a little higher, but I wonder if that would cause problems when slicing. (kind of like when a feature is smaller than your mill bit and the CAM software skips that cut)

Has anyone played with this and checked parts for accuracy with a GCode visualizer? I think this would also come into play with things like holes being undersized and towers being oversized...