1st and last concentric shell layer seam hiding?

[mhackney]

I probably know the answer already since I have scrutinized the forum and gone thorough all the slicing parameters but just in case I missed something...

When printing concentric shell layers there is is obvious seam line right through the part because every concentric pass starts at the same angle. Ideally, I'd like to randomize or stagger the start point by a specified number of degrees. Is there a way to do this or a work around?

[CompoundCarl]

not that I know of. but I would think randomizing where each concentric perimeter starts would make make many more defects in the top layer. you always want to print perimeters with their start and end points as close as possible.

to prove this for myself, I printed a simple shape with concentric top layers and then wrote a script to randomize the starting points for each concentric perimeter. It looked much worse than printing them normally, since the extruder now has to make long movements to the location of each new concentric perimeter. looked really bad.

The way it works normally seems like the right way to go. it moves quickly to the next concentric perimeter and doesn't make any long moves or marks

[mhackney]

Thanks for the reply. For your context, you may be correct. For my context, having the defects spread around is a better solution. I have hand rolled first shell concentric fill on KISSlicer output and the result was excellent. I actually moved the new start point 10° - not randomized although I think random placement would have been just as satisfactory. The translucent PLA I print with the infill showing through hides small defects but not a seam line.

[mhackney]

Well, there is a workaround for the brave of heart and those with intestinal fortitude. Read on...

Simplified version, I'm doing something a little more complex to get a wider concentric band at the perimeter of the disk and a different effect near the center:

Basically, I edited my model so the first .4mm (the side facing the build plate) is a series of concentric rings .8mm wide. These numbers were chosen since I print .2mm layers (so 2 layers) with a .4mm nozzle. I then create a process for this first layer that has 1 perimeter configured. S3D prints each of these bands in 2 passes, 1 perimeter one direction then reverses for the inner most perimeter. It staggers the starts of each band (apparently randomly) so the bands do not have start points aligned. This gives the results I'm looking for albeit most of the work is designed in the model. I tie the bands together with Rectilinear fill on the layer starting at .4mm.

You will have to play with coast, wipe and retract to get the ends of each band to reliably close but I had that sorted out already.