Perimeters do not touch

[TMeyer]

Hi,

I have a problem with non touching perimeters.
I have an object with 4 perimeter shells. I print from outside to inside.
During printing I can see that only the 1st and 2nd outer perimeters touch well. The 3rd and 4th have a gap.
What I can observe is that the outer most shell is printed slowly and for each further shell the speed gets increased - this causes the gap.
But I cannot see any setting to avoid increasing speed for shells.

What I did now is I increased temperature and extrusion multiplier - then the gaps are closed but then I have too much filament in other areas of my object.

Why S3D increases the speed for outline shells if it moves inwards (if printing shells from outside to inside)?

What can I do now?

[brian442]

Printing at a different speed shouldn't change the amount of plastic that is extruded. So if you're finding that different speeds change how much plastic you get, you probably have a bigger issue (perhaps your acceleration or jerk settings are too high and the extruder can't keep up??)

[TMeyer]

@brian442,

thanks, that is a good thought. I checked my settings but could not find any wierd speed / acceleration setting as you can see here:



You can also see that inner paths of the periemter are printed at higher speeds compared to the outer ones.
As you can see my max. printing speed is 55mm/s. The preview on the left shows green areas of much higher speeds something like 75mm/s.

Where does this higher printing speed for the inner perimeters come from?

Thanks for any further help...

[brian442]

Acceleration and jerk are firmware settings, so those can still easily be wrong even if your speeds in S3D are correct. I'm just trying to say that if your printer is extruding different amounts of plastic at different speeds, you're going to have a lot more problems in the future, so I would try to sort that our first.

S3D uses the outline underspeed for the outer-most perimeter, then starts increasing towards the default printing speed for inner perimeters, so what you're seeing is normal. But again, I would fix the extrusion issues first.

Try editing your firmware config to reduce XY accel and jerk by 50%

[TMeyer]

Hi brian442,

thanks again. What do you meant by editing the firmware config?
Is this someting I have to do inside S3D? If yes where please?

And what is 'jerk' please?

BTW: My printer is an Ultimaker 2 - so I used the default profile from S3D - are you sure I have to tweak something there?

[brian442]

Acceleration and jerk are firmware settings. So you can edit in the firmware Configuration.h file, or use M201/M205 and other custom commands to make the changes over USB.