True Spiralize Mode

[oneearthtech 0]

Hi Cura People. 

I use Sprialize Outer Contour Mode alot to print large objects using PETg.

Heres some more info:

Build Volume = Delta 600 x 350D

Print Speed = 8mm/s

Line width = 2.5mm

Layer Height = 0.7

This thread falls into Feature Requests but let me know if there are ways to mitigate the following issues in the current version.

Not Truely Sprialized
 

This issue relates to the bottom layers. Cura starts by printing the outside wall then proceeds to Sprialize from the inside out requiring the need for travel and/or retraction. If multiple bottom layers are set, this happens on every bottom layer leaving a Z Seam (Sprialize Mode + Wide layers are being used to avoid a Z Seam while maintaining wall strength)

Issue 1: Bottom Layers are not Sprialised

Ideally the bottom layers would Sprialise in one continuous motion as to not form a Z seam. This would mean starting at the centre and working outward or vic-versa without travel or retraction. . However, using the current version Cura first prints the "outerwall" as shown in red below before moving inward to start Sprialising the bottom layers (yellow) outward.

Potential Fix :

There are two cases to consider: Odd and Even bottom layer counts.

Case One: Even Bottom Layer Count

When setting Even numbers for the bottom layers the print could start with the outer line first then work its way to the inner most point then raise up and sprialise back outward before continuing in a smooth motion to build up the walls above the bottom layers. This may leave a small artifact on the first loop when the print head moves inward but this could be avoided if Bottom layers were limited to odd numbers. 

Case Two: Odd Bottom Layer Count

When setting Odd numbers the print head could start in the centre of the model, work outward to the outer wall - z lift - then back in to centre - z lift again- before proceeding outward before building up the outer wall once the bottom layers are finished. This could lead to a truely continuous print. 

This would help to limit retraction/travel and a much smoother "Vase Mode" type print.

Issue Two: Inner Walls Generated in Bottom Layers

Sometimes the bottom layers will print with an Inner Wall (shown in green), leading to retraction and not a "True Sprialised Mode".
 

I look forward to hearing from you.

Talk soon

Matt