minimum width for a given nozzle diameter

hi everyone,
i'm beginner of 3d printing, and i'm tyrying to understand the basic theory of this new world.
so this is my first (of many others) question.
if i have a nozzle diameter, call it D, the width can't be less than D: w>= D. is it correct?
so, for example, if D = 0.5 mm, and i use a layer height (h) of 0,1 the minimum width ratio (width over eight; r=w/h) is 5!!!!
instead, if i use r = 1.8 (the default value of skeinforge, the minimum value of h is 0.28.

maybe i'm doing something wrong. or not?

For optimal printing you want the width to be at least the nozzle diameter, so you use whatever w/h ratio is necessary to get that at your desired layer height. With a 0.5mm nozzle and 0.1mm layer height, you are correct that you would need a w/h ratio of 5. 0.1mm layer height is not optimal for a 0.5mm nozzle but it can be made to work. With a 0.4mm nozzle I get good results with a print width of 0.4 to 0.5mm and a layer height of 0.2mm, which is a w/h of 2 to 2.5.

The default settings in skeinforge aren't always optimal, so just remember that.

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I find 0.1 layer from a 0.5 nozzle is great. The larger the nozzle the lower you can go as a result of the volume of plastic being extruded with each step.

Check the calculator in my signature. It will give you the correct width for any given height and nozzle. Be sure to use the intermediate or advanced since you do not have a Tantillus. Also be sure to enter you Z and E steps per mm to get the most accurate results.

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thank you guys for your answers.
Cameron, ok so i was going in the right way. but why do you say that 0.1 mmm is not an optimal layer height for a 0.5 mm nozzle diameter?

Sublime, your tool seems great. but i canpt understand something.
what does extactly mean "Die Swell"?
which is the difference between "Nozzle Diameter (mm)" and "Nozzle diameter used for flow calculations (mm)"?


adm

If you extrude into free air and then measure the extruded filament it will be larger then the nozzle hole. This difference is the die swell. A value of 0.2 is a good starting place and is usually safe. If testing try to test the free air extrusion at around the same extruder speed as printing would be. By this I mean look at the hobbed bolt while printing and try and set a speed for the free air extrusion test so that the hobbed bolt looks to turn at around the same rate.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

adm Wrote:
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> Cameron, ok so i was going in the right way. but
> why do you say that 0.1 mmm is not an optimal
> layer height for a 0.5 mm nozzle diameter?

The only reason I say this is that infill and bridging does not work as well. The cross-section of the extruded filament at 0.1mm layer height and 0.5mm nozzle is only 0.05mm^2, vs the cross-sectional area of the nozzle at pi*(0.25mm)^2 = 0.2mm^2. This means that the extruded output is being stretched quite a bit, and it tends to snap when crossing bridges and sparse infill.

Of course this doesn't mean that you can't get nice prints at 0.1mm with a 0.5mm nozzle, just that it's a bit harder than say 0.25mm layer height.

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ok, Cameron. i see. i'm going to make some test and i'll show you the results .
Sublime, now i understand. i'm doing some calculation with excel and i'm going to calculate this parameter. thank you.