Infill weak with higher speeds

[conny_g 251]

Hi all,

I am using the 3DSolex Matchless nozzles and can print easily with 60mm/s in general.

There is just one issue that I can't seem to resolve:

Even though I set the line width parameter to 0.6mm (with 0.4mm nozzle and 0.35 line width otherwise) in Cura to force higher extrusion the infill is very weak.

With lower speeds (40mm/s) the infill is ok.

Are you having the same issue? How can I resolve it? Is it the right approach to use the infill line width parameter?

Thanks,

Conny

[conny_g 251]

After some searching, reading I think I got it.

It's a matter of the spread of speed between walls and the infill.

Cura sets the infill speed like twice as high as the walls, so the infill is hit much faster with any underextrusion issues of the "temperaturs/volume per time" parameter.

Then I would need to set the temperature high enough that this still works, but then there is other effects like the extruder can't build the pressure fast enough and part of the infill in small areas is done before the higher line width would help. Or I get stronger stringing etc.

So it's a matter of compromises - either I print fast and tolerate weak infill or I print slower (at least the infills) and the spread of speeds is less strong.

[kmanstudios 1,120]

....... or I print slower (at least the infills) and the spread of speeds is less strong.

 

I am not sure that I understand. Would you please elaborate?

[conny_g 251]

 

....... or I print slower (at least the infills) and the spread of speeds is less strong.

 

I am not sure that I understand. Would you please elaborate?

 

If I set the print speed to 65 mm/s then Cura sets different speed levels for "sub tasks" like inner wall, outer wall, infill etc.

Cura sets infill to 65 and outer wall to 42, that's what I mean with "spread" of speeds, infill is 50% faster.

That's a good idea as infill does not need to be as "nice" as outer walls. But it has the effect that physics vary between these two - the 65 require a higher temperature to be able to extrude the corresponding amount of material.

And this "gap" or "spread" becomes more challenging the more you increase the speed, up to the point where it's not possible to find a setting that is working for both, either you have too low temp for the infill or too high temperature for the outer walls.

For the material I am currently using to print a large object (20 hours at 0.2 layers) - Extrudr Green-Tec - I can't get the infill to work if I have the speed in Cura at 65mm/s, I needed to slow down by 30% to get it work ok.

Not sure where the temp limit of Green-Tec would be, didn't want to try with the object in the making, will run a test afterwards. If Green-Tec is still happy at 255 C it might just work.

So it seems to also depend on how much the viscosity of a material changes with temperature, I have less issues with other materials.

So it seems that this "spread" limits your speed, depending on the material and how urgent you need the infill. If it doesn't work you need to set infill slower vs. outer walls.

[kmanstudios 1,120]

I gotcha now Thanks and I concur.