Printing Small Circles With Good Quality

Without slowing the whole print down, does Cura have settings that adjust the print speed / jerk / acceleration when printing small circles? If not, is there a way to adjust these values with some script or post processing and will changing them make a big difference in print quality of small circles / spires?

Well, Cura does have the ability to change jerk and acceleration settings for different parts of the print such as inner wall, outer wall, top/bottom, infill, etc. However, there is nothing specific to just “small circles.” However by adjusting these settings, you should be able to achieve finer control without reducing speed.

Thanks Brent!

It looks like I have the following settings for jerk / acceleration:

#define DEFAULT_XJERK 8.0
#define DEFAULT_YJERK 8.0
#define DEFAULT_ZJERK 0.4
#define DEFAULT_EJERK 15.0

#define DEFAULT_MAX_ACCELERATION { 9000, 9000, 100, 10000 }

  • Default Acceleration (change/s) change = mm/s
  • Override with M204
  • M204 P Acceleration
  • M204 R Retract Acceleration
  • M204 T Travel Acceleration
    #define DEFAULT_ACCELERATION 500 // X, Y, Z and E acceleration for printing moves
    #define DEFAULT_RETRACT_ACCELERATION 3000 // E acceleration for retracts
    #define DEFAULT_TRAVEL_ACCELERATION 3000 // X, Y, Z acceleration for travel (non printing) moves

Please let me know if you have a first iteration suggestion on which values to tweak and by how much. I’m guessing jerk would be most important for small circles, but I’ve never been down this road before.

Also, the jerk and default acceleration numbers seem kinda low to me. Are they correct for the TAZ 6?

Those are the correct settings for the TAZ 6. We do have them set conservatively, as we like to ensure reliability in a variety of situations.

However, before you go and change the firmware I would highly recommend some tests prints using Cura LE. While marlin can control acceleration and jerk in general, Cura LE can change those parameters based on different sections of the print. This will give finer control while not reducing speed.

To activate these go to custom settings, speed, enable accleration/jerk control. This will then show many different sections where you can experiment quickly. Once you find the settings you like, we would then recommend updating your Marlin acceleration and jerk settings. (Should be quicker than modifying firmware each time)

Thanks Brent!

It looks like Slic3r has a Small Perimeters feature which has a separate speed setting for Perimeters vs Small Perimeters. I think that would come in handy if Cura had something like that. The only way I know to slow down the print speed for Small Perimeters is to slow down all Perimeters which adds a fair amount of print time.

Here’s slic3r’s Small Perimeters Setting that I’m talking about:
Here it is in the gcode printing some spires. The acceleration is reduced for perimeters along w/ the print speed when printing these spires:
Since the TAZ already has conservative Jerk and Acceleration settings it looks like I’m going to need to slow down the printing of all perimeters to print small perimeters w/ better accuracy. Unless you know of a way to do this w/ out slowing down all perimeters? Thoughts?

Looking into Slic3r, it looks like it will use that setting when a radius is less than 6.5mm. Cura can call out inner walls, outer walls, infill, support, etc but currently doesn’t have that ability.

What specific issue are you having with your circles, can you post a photo?