Custom Flow Rates for Different Types of Lines?

[CalebPetersenPhD 0]

Hi, is there any way to selectively increase the flow rate just for infill?  I know you can change line widths for different features (infill, top/bottom, etc.), which is great, but with larger line widths for infill (and even with moderate print velocities and reduced print accelerations for infill) I'm a bit of infill underextrusion.  (Print temperatures are more than sufficient)

 

For that matter, being able to selectively increase the temperature for infill lines would be cool.

 

I suppose this could be done with dual extruders (use a larger nozzle, extra flow multiplier, and higher temperature just for infill)...

[burtoogle 509]

Hello @CalebPetersenPhD, this feature has been programmed but hasn't yet made it into Cura (see https://github.com/Ultimaker/Cura/pull/4561).

[CalebPetersenPhD 0]

Thanks for the response @smartavionics, I looked into it a bit more and it seems like that page you linked is saying that you can edit expert.cfg in /resources/setting_visibility by adding the following lines to the [material] section:

wall_material_flow

wall_0_material_flow

wall_x_material_flow

skin_material_flow

roofing_material_flow

infill_material_flow

skirt_brim_material_flow

support_material_flow

support_interface_material_flow

support_roof_material_flow

support_bottom_material_flow

 

And also moving prime_tower_flow from [dual] to [material].  But when I do this in my Windows installation of Cura 4.0 and then relaunch Cura, the flow settings still aren't available... do I have to build it from source?

 

[burtoogle 509]

Hi @CalebPetersenPhD. Cura is basically a two-part application. The front end that provides the UI and all of the settings stuff and the back end (CuraEngine) that actually does the heavy lifting to turn the model into g-code. The PR I cited above is what is required to be changed in the front end, there is also a PR that makes changes to the back end. So without both PR's being applied and the application rebuilt, it's not going to be effective. There seems to be a bit of a log jam with the processing of contributions to Cura at the moment so I really can't say when they may get around to evaluating that contribution and considering incorporating it into a future release. Sorry to have got you all excited!

[CalebPetersenPhD 0]

Oh, got it @smartavionics!  Is there any way to set deafults in a text editor for those flow settings so that even if they don't appear in the UI they're still used by the CuraEngine?

[burtoogle 509]

1 hour ago, CalebPetersenPhD said:

Oh, got it @smartavionics!  Is there any way to set deafults in a text editor for those flow settings so that even if they don't appear in the UI they're still used by the CuraEngine?

 

The engine needs to be modified and rebuilt too so without doing that, you can't change how it works.

[CalebPetersenPhD 0]

Dang... well let's hope they get it added in there! In the meantime, maybe I could create dummy extruders for my UM3, assign them the various roles (wall, infill, etc.) and flow rates, and then post-process the Gcode with a simple find-and-replace to change all T3, T4, etc. to T0.  Looks like I can change the number of extruders in the ultimaker3.def.json file.

[burtoogle 509]

So, @CalebPetersenPhD, back to the original problem. I assume you are using 100% infill? I ask because, if my memory serves me right, when you specify 100% infill it actually doesn't use infill anyway, it just uses skins instead and so it will be the skin speed and flow that is limiting the achieved extrusion rate.

[CalebPetersenPhD 0]

Actually, I'm often using only 20% infill and just want really thick, wide infill lines like I can easily get in Simplify3D.  (In fact, the one and only thing that Simplify3D seems better at than Cura is infill! Kind of pathetic how far behind S3D has fallen.)  When I increase the infill line width in Cura, it doesn't seem to make the infill lines any thicker in prints... and this is with infill print speed and acceleration turned down.  With the default settings, my infills would be horribly underextruded, a problem that people have had with Cura for years.

[burtoogle 509]

10 minutes ago, CalebPetersenPhD said:

With the default settings, my infills would be horribly underextruded, a problem that people have had with Cura for years.

 

That's weird because I don't have any problem with that at all. I suspect that your extruder is underperforming for some reason. Have you actually checked the calibration at the extrusion rate required for the infill you are printing?

[CalebPetersenPhD 0]

No, I haven't ever tried to calibrate it!  I have performed nylon cleanings and cleaned out the gearbox but since reducing acceleration and infill speed at least solves the problem of infill underextrusion for a standard line width that's a start...

[CalebPetersenPhD 0]

Looks like Cura 4.1 Beta doesn't add this feature 😪

 

Simplify3D has very few advantages over Cura, but proper, fat infill lines when you assign a fat line width is one of them.  Seems like an easy fix, hope this feature gets added.

[burtoogle 509]

Yeah, but don't forget to calibrate your extruder as discussed above!

[CalebPetersenPhD 0]

But all non-infill extrusions are not underfilled at all.  Infill only ends up being grossly underfilled when I set a larger infill line thickness (e.g. 0.6 for a 0.4mm nozzle).  Whereas Simplify3D produces G-code that makes proper infill lines when I use a default line width of 0.48mm for a 0.4mm nozzle and have the infill line width further inflated by around 130%.

 

People have speculated that there is a bug in Cura that causes it to not increase the fill rate commensurate with how the infill line thickness is increased.

[burtoogle 509]

10 minutes ago, CalebPetersenPhD said:

People have speculated that there is a bug in Cura that causes it to not increase the fill rate commensurate with how the infill line thickness is increased.

 

Hmm, let's just do a quick test of that speculation...

 

Firstly, I used infill line width of 0.6mm and this gives an extrusion rate of 0.075 mm/mm

 

 

I then sliced again with an infill line width of 0.7mm and now I see an extrusion rate of 0.087 mm/mm

 

 

0.7/0.6 = 1.1666

 

0.087/0.075 = 1.16

 

OK, so the ratio of the infill line widths doesn't quite match the ratio of the resulting extrusion rates but it certainly doesn't look like a gross error there. At worst, there's a small rounding error but that may just be due to the short segment lengths used in this example.