Tried that in the past-Cura Host. Stuff runs gooflooky. IE- Cancel print, nozzle/ bed wont stop heating up, etc.
I dont have to change anything in Rep FW ?

Someone needs to combine the good of Slic3r and Cura - CurSlicr

The L bracket was printed w/out Spiralize.
Decreased perimeter speed from 40-20. That got rid of the bad corner.

Test prints
Printed 0 Infill Shell Thickness, 0.3 layer ht.  btw- the Shell Thickness input space turned red ?
Slicer preview shows infill ?

20x20x3mm = 3.06mm wall measured   3/3.06 = 0.98
20x20x2mm = 2.20 wall measured    2/2.20 = 0.91
20x20x1mm = 1.21 wall measured   1/1.21 = 0.83

Now what ?

Lets say you want to print a cup with a 3mm wall. Lets say you find out your print width for a .3mm layer is .40mm just hypothetical numbers here. What you would want to do is divide the cups wall thickness (3mm) by the known perimeter value (.4mm). You could make the cups wall with 7.5 perimeters of course you can't print a half perimeter so you can't make the wall with all perimeters. So what we would do is use 3 perimeters. That will put 3 on the outside and three on the inside and then the slicer would infill the space between which would be .6mm which may or may not fill to the edges since .6 won't really divide by .4. Yo may have a .2mm gap between the infill and the perimeters and again you may not.

But you get an idea of how the math works.

I would also not use the spiral function on anything but round objects with single perimeter walls such as a vase. It is supposed to make a continuous extrusion but can't because you are not printing a round object and your object has multiple perimeters..

If you hover your mouse over the various settings there should be a tooltip that pops up and explains what the function does and what it would normally be for.

And when you say design your wall, is that the actual model thickness or perimeter thickness ?
To have an infill there must be 2 perimeters, combined is wall thickness.

In Curaengine if want a solid wall, no infill, do you input 0 for Shell Thickness ?

Just printed an ABS 40x40 L bracket .2 layer, shell .5
Breaks easily between layers. This ABS black is not easy to print. Ill try slower speed and temp increase.
But, Again that rough Z seam on the corner where slicer changes travel.

Yes flowrate can be changed but during the print it remains at that setting unless you change it or the gcode changes it.

So in a nut shell you want to design your walls so can be evenly divided by your nozzle diameter or you may find gaps where the extrusion may not meet the previous wall, or when doing solid infill the infill may not make full contact with the wall.

Correct ?

What is the reason for this ?

Ok, done more searching on this subject, seems that the Z seam is an artifact of Spiralize.
And Spiralize prints w/ no infill. But can add a plugin, Swap at Z, in which cant do w/ Curaengine.

No wonder print time was cut in half.

But most of all, NO INFILL. How do i get infill w/ spiralize ?