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difference between settings in layers and perim and advanced

Posted by ruggb 
difference between settings in layers and perim and advanced
October 08, 2020 10:32PM
Under layers and perimeters, there is a setting for first layer height. default is 0.35mm
Under advanced there is a setting for first layer.
It says this is computer over first layer height and the default is 200%.

If I select a layer height of 0.1mm then I probably would set the first layer height to 0.2mm and not leave it default.
However if first layer is default, then it looks like my first layer will be 0.4mm instead of 0.2mm

Can someone explain how to use these settings?
thanks

Edited 1 time(s). Last edit at 10/08/2020 10:33PM by ruggb.
Re: difference between settings in layers and perim and advanced
October 09, 2020 07:04AM
% of what? Specify the number in mm so you know at a glance what the setting actually means without having to do any mental gymnastics.

If your printer's bed is flat or if you have some active compensation for an unflat bed, just set the first layer thickness to the same value as all the other layers, in mm. That of course, is based on the nozzle diameter and desired print quality. Don't try to print layers that have thickness = nozzle diameter. Keep the layer thickness around 50% or less of nozzle diameter and you'll get strong prints with good interlayer adhesion. If you want something to print fast as a test you can bump the thickness up a bit from there, but not much.

I believe the first layer thickness adjustment was originally included to help get the first layer to stick to unflat beds, back before people understood how to make a flat bed and how to tram it properly, and certainly before autoleveling was widely used.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: difference between settings in layers and perim and advanced
October 09, 2020 07:25AM
thank DD. The % is right from the tool tip.
Using a 0.4 nozzle, for detailed prints I set 0.1mm layer and 0.15 first
for large prints I do 0.3 and 0.35

The question is related to two items that seem to do the same thing and why they are there.

Under layers and perimeters, there is a setting for first layer height. default is 0.35mm
Under advanced there is a setting for first layer.
It says this is computer over first layer height and the default is 200%.

If I select a layer height of 0.1mm then I probably would set the first layer height to 0.2mm and not leave it default.
However if first layer is default, then it looks like my first layer will be 0.4mm instead of 0.2mm

The same question for layer height and Default extrusion width. Is there a difference? and If so, how are they used?

Edited 1 time(s). Last edit at 10/09/2020 07:32AM by ruggb.
Re: difference between settings in layers and perim and advanced
October 09, 2020 01:00PM
The Advanced tab is for setting line widths, not layer thicknesses.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: difference between settings in layers and perim and advanced
October 09, 2020 01:17PM
Be nice if people could communicate, Default extrusion width would suggest that, but first layer height sure does not. So, that should be FIRST LAYER WIDTH?

So, if I have a first layer height in l&p of 0.2mm and a first layer "width" of 200% (default) in advanced what do I end up with?
Re: difference between settings in layers and perim and advanced
October 09, 2020 02:03PM
Indeed, what do you end up with? 200% of what? How much is that in mm?

If you're modeling something to be 3D printed, and the slicer/printer controller work in mm, do you model in feet and inches, or do you use mm? If you use feet and inches, everything has to be converted to mm before it can be printed. Why would anyone do that?

For some reason, the slicer has options of specifying line widths and layer thicknesses in % and mm, and it defaults to %. That's not too different from modeling in feet and inches. It adds an extra, wholly unnecessary step to the process (In this case the mental process of setting line widths and layer thicknesses) and creates an opportunity for error.

Specify all the line widths in mm. If the nozzle is 0.4 mm diameter, set your line width to 0.4 mm or maybe a little more (but not much more- maybe up to about 0.5 mm or so).

If you set default extrusion width to some non zero value and then set all other line widths to 0, Slic3r will pick the line widths based on the default width that you set. What widths will it use? Who knows! If you use % and/or you let the slicer choose line widths and layer thicknesses, and you don't like the way the print looks, what will you change to fix the problem? Specifying everything in mm ensures you know exactly what you're going to get and that way you'll know exactly what you need to tweak if you don't like the resulting print. You can see a preview of the print by looking at the rendered gcode. Sometimes you can eliminate gap fills that are slow and often shake the printer by tweaking the perimeter line widths. Don't print until you like the way the rendered gcode looks! Tweak lines widths, number of perimeters, layer thicknesses, etc. until it looks the way you want in the rendered gcode. Then export the gcode and print.

And absolutely never, ever, set the line width smaller than the nozzle diameter.

If you don't want to have to specify all that stuff and just want the slicer to handle everything for you, don't use expert settings.

Edited 2 time(s). Last edit at 10/09/2020 02:12PM by the_digital_dentist.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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