Problem with hole sizes

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Re: Problem with hole sizes

Postby tmccafferty » Mon Apr 08, 2013 7:57 pm

I printed your file and the parts fit. The male part of your prints are smaller than mine and the holes of yours are bigger than mine. However, the horizontal fill like the bottom of mine looks better. I guess I'm just extruding more plastic in my slicing.

Is there a way you can send me your slicer settings?
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Re: Problem with hole sizes

Postby flurin » Tue Apr 09, 2013 6:20 am

I use 8 different configurations for slic3r, config60.ini is an example.

See also:
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Re: Problem with hole sizes

Postby Digitalmagic » Tue Apr 09, 2013 10:48 am

SystemsGuy wrote:? Can you elaborate on that?
Digitalmagic wrote:Now, for the small hole/perimeter, the spaghetti width is rather managed by nozzle dia field than by extrusion factor (flow control).

The slicer (software / algorithm) must know the pastic flow as best as possible to obtain the right deposition (FDM).
4 major factors are:
- Real filament diameter
- Real extrusion diameter
- Calibrated filament advancement:
- Layer height

In this context, tweaking the nozzle diameter or the extrusion factor are different.
- Like you do in the filament diameter field, where you enter the measured filament you install, this is the same for the nozzle diameter, it is better to enter the measured spaghetti diameter (unless the slicer mentions that it computes this nozzle to spaghetti expansion).
- With accurate entries for filament and spaghetti, you get input section and output section, leading to a ratio.
- combining this ratio to the real filament advancement, you get a plastic flow, which is quite accurate, as you entered real/measured values.

If correctly measured entries have been done, you should not need to use the extrusion factor.
The extrusion factor is a pure tweaking tool, allowing to adjust the plastic quantity by any means, estimating what you see by trial and errors, by example.

Finally, the layer height combined to the nozzle/spaghetti diameter is very important to understand because you will get very different results, from flat to round.
You can notice that in the first layer, depending on your settings, Z-adjustment and slicer options, producing a thin and flat printed path (later the part bed side appears continuous and shiny).
At the opposite, when the layer matches the nozzle/spaghetti diameter, the extrusion is rather round shaped.

That's why I told that prior to tweaking the extrusion factor, it is wise to first enter measured values to tweak/increase the nozzle diameter, the spaghetti being always larger than the nozzle diameter.


EDIT: The schematic takes the nozzle geometry in account to compute the extrusion ratio.
If the spaghetti measured diameter (0.41mm) is used instead (preferably), the extrusion ratio decreases to 13,82.
How many slicers algorithms manage entered values would be a good thing to be published, to better tweak/calibrate precise extrusion.
Filaments are not born the same, and this can play a role, too. By example, I find some flavors being "sticky" when others are "flowing", etc...
I play with the extruder temp during extrusion to see how it interacts with printing quality "on the spot".

The nozzle deposition linear speed is accurate if the filament speed is accurate (calibration) and if the real sections ratio is accurate, too.
In each Xx Yv Ed G-Code line, d is the filament advancement, and the nozzle displacement can be computed with previous coordinates and (x,y) and type of displacement (rectilinear or circular G2/G3, more exotic).
There is a fixed ratio between d and displacement[previous point to (x,y)], expressing the extrusion ratio, probably combined with other slicing factors.
Last edited by Digitalmagic on Wed Apr 10, 2013 10:04 am, edited 2 times in total.
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Re: Problem with hole sizes

Postby tmccafferty » Wed Apr 10, 2013 2:56 am

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Re: Problem with hole sizes

Postby Digitalmagic » Wed Apr 10, 2013 9:27 am

tmccafferty wrote:Here is an interesting related post

Very interesting. This post from Richrap is very informative for filament advancement calibration.
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