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Slicing with cura + joris.


Posted · Slicing with cura + joris.

In theory, when the extruder is commanded to extrude, plastic comes out. When the extruder is commanded to stop extruding, plastic stops coming out. That's the theory. In practise, plastic continues a bit after the extruder is commanded to stop. The blobs arise when plastic comes out while the extruder is told to stop.

For example, when building a "cup", the "old fashioned" way of doing things is to do a loop around the cup, stop, increase Z by the layer-height, and then do the next layer. All good, but the plastic continues to come out for a little while when the extruder is stopped. So you get a blob. And possibly holes on the next part where not the expected amount of plastic comes out.

With an object like a "cup" or the pink panther woman, there is no reason to stop moving. With "joris" enabled the Z-movement is spread out over the whole outerloop. Therefore there need never be a stop, move Z, start. And after a short while, the plastic flow will have stabilized and be perfectly smooth. So you get a nice smooth object.

This morning I designed an interesting object. Specifically designed to NOT be disjunct: The head should be able to keep on moving. No jumps required. This resulted in a beautiful print. Only on the first layer of the top-fill, the head hit the object and bumped it off the bed. And it burned a hole in the last few mm of the object. Oh well.

Openscad however had rendered this quite coarse. So I figured out how to make that more smooth, and I went for it again. Same object, slight change in aspect ratio, but still a simple closed contour on EVERY level. However this time when cura slices it, I see a blue "travel" line in the gcode-preview. I'm not going to waste filament on this: this is not going to come out as I want.

I'm still reading cura-code to see if I can find the offending code....

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