Outer wall issue with bowden printer

[cuccuc 0]

Hello

 

Happy Cura user new to the community. I am having a little problem, I like to print the outer wall slower than normal for extra surface quality but what I'm experiencing is uneven extrusion on the beginning of the outer wall. Some centimeters into the wall the extrusion becomes nice and even.

I am fairly certain that this is an issue with the pressure in the bowden tube being too high or too low at the moment the outer wall starts, so I tried adjusting the pressure before going into the outer wall using a number of things

 

* avoid traveling before printing the outer wall

* coasting -> hard to control the right amount of pressure

* printing walls inner to outer with the same extrusion rate -> works but prints slow

 

I was wondering, is there a setting I'm missing in Cura that would allow me to adjust the extrusion rate to the one of the outer wall about a few centimeters before actually going to print it?

 

Cheers!

[yellowshark 148]

Yes often a tricky one; you have an inherent problem caused by the required change in pressure which does not happen instantaneously, it takes time to settle down. That is why 99% of the time I print with all speeds set to the same value.

With regards to your last comment, I have often wondered why Cura does not allow you to specify the speed change to happen during the last part of the infill.

 

I am only on 2.7 and so not aware if there have been subsequent changes that would help. All I can think of is to print the wall inner to outer and if need be add an extra wall. I normally go outer to inner because that is meant to improve dimensional accuracy which is normally important for me.

Also if you are printing something, maybe a bust, where there is a definite rear which will not be seen, then use the “user specified” option of the Z Seam Alignment to start the layer on the rear section.

[smartavionics 288]

Turning on retract before out wall should help.