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Gap fill option

Posted by maddis 
Gap fill option
January 18, 2017 07:36AM
Hi,

I've been using Slic3r with my, not so expensive 3D printer for few months now and slowly the settings are getting there. The print quality in general is satisfactory considering price of the machine, but there are some issues. Some might be from machine some maybe from slicer. I'm using Slic3r v1.2.9.

The one I'm not sure if it's coming from machine is the Gap fill - option in Speed - settings. With it set to 0 (ie. disabled) the print is otherwise okay quality, but thinner perimeters tend to have two separate perimeters(or inner and outer shell).

With the Gap fill set to for example 20mm/s it seems that the Gap gets overfilled and nozzle starts hitting to it after awhile.

Here is the picture what happens with that Gap fill setting. If you look at the outer edges you can see kind a wavy pattern. That doens't happen if Gap fill is disabled. That example has so thick outer perimeter that there are no separation happening, but for example if the perimeter is 1mm it does happen (guess the 0.4 nozzle produces 0.8mm perimeter and slicer adds the 0.2mm that doesn't get filled).



Here is picture from the side after letting it print completely. On the left is Gap fill - option on and on the right without Gap fill. On the right there is also support enabled, but that makes no difference in this case.



The reason why I would want to use the Gap fill is to get rid of the separation of the perimeters on narrower perimeters if that makes any sense. Or are there any alternative options I could try?

I'm printing with PLA.

Edited 1 time(s). Last edit at 01/18/2017 07:36AM by maddis.
Re: Gap fill option
January 19, 2017 12:11AM
Set the gap fill speed to "0". It is a known bug.
Experiment with extrusion width instead to find a setting that fills the gaps.
Re: Gap fill option
January 19, 2017 04:49AM
Yes, it's the perimeter extrusion width you should play with to get thin walls completely filled. Or adjust the wall thickness in your model. It will also print faster than filling (only 2 passes per wall instead of 3)

Dave
Re: Gap fill option
January 20, 2017 06:20AM
What option you are exactly talking? I already have 3 perimeters. Seems that 1mm think wall in model end up being printed in two perimeters and they are not attached to each other.

I did little testing with the extrusion width. I have 0.4mm nozzle and I told to Slic3r that it was actually 0.35mm. That seemed to help help in this case. I might test with 0.38mm or something if the 0.35mm end up using too much filament.
Re: Gap fill option
January 20, 2017 11:12AM
Don't change the nozzle size in the printer settings tab, but change extrusion width in the advanced section of the print settings menu
Re: Gap fill option
January 21, 2017 12:28AM
Aha, got it! I've been there before, but didn't remember that option just now. Seems that I might be able to fix the problem with those settings. Need to play with those settings bit more. Thanks.
Re: Gap fill option
February 07, 2017 09:09AM
Lately I noticed that that extrusion width setting plays havoc on print time. For example with one part with auto extrusion width the print time was 3h 23min. Same part with extrusion width 102% the print time was about 8h 30min or so. So I'll have to find another solution for bigger parts.
Re: Gap fill option
February 07, 2017 05:29PM
102% will usually not be an appropriate setting for extrusion width. It is computed against layer height, which is usually recommended to be no more than around 75% of the nozzle diameter, so if you're following that guideline you're setting extrusion width to just over 75% of the nozzle diameter or less. Extrusion width should usually be equal to or greater than nozzle diameter.
Re: Gap fill option
February 08, 2017 03:52AM
Quote
IMBoring25
102% will usually not be an appropriate setting for extrusion width. It is computed against layer height, which is usually recommended to be no more than around 75% of the nozzle diameter, so if you're following that guideline you're setting extrusion width to just over 75% of the nozzle diameter or less. Extrusion width should usually be equal to or greater than nozzle diameter.

Exactly so. With much thinner extrusions it will need a heck of a lot more passes (lines) to get the same result, hence the far longer print time. Set the width in mm rather than %. Choose a width that is very slightly less than an exact division of the most common wall thickness of your part.

Dave
Re: Gap fill option
February 08, 2017 10:05AM
Okay, it seems I misunderstood the parameter then. I thought the width was counted from nozzle diameter not layer height. I'll try the mm setting.
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