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Samon

Vase mode solid bottom offset

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Hello everyone! This is my first post so please don't beat me 😉

 

I'm trying to print a model (upside down from STL file ) in vase mode with solid bottom layers.

The problem is that after adding bottom thickness the model surface is no longer continuous,

there appears a step - see the photo ( preview in S3D because Cura does not show it ).

 

Could you help me get rid of the step?

( I removed everything from config folder, set up nozzle, layer height, spiralize and bottom thickness )

 

Thank you !

 

offset.png

flat.stl

Edited by Samon
Added stl file

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Hello @Samon, the spiralize mode starts the spiral wall after the bottom layers have been printed. The first spiral layer starts at the same height as the last bottom layer so at the very beginning of the spiral the filament will squish out as the effective layer height is zero at that point. By the time the first spiral has completed, the nozzle will have been raised by 1 layer height. So you will always get some extra filament around the first spiral layer. Ugly? Yes, but it does increase the likelyhood of the printed object being waterproof.

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I am thinking that you could try the "Initial Layer Horizontal Expansion" Set to a negative number. It seems the effect you are getting is 'elephant's Foot' and that was designed to offset that. Give it a shot, it may help.

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4 minutes ago, kmanstudios said:

I am thinking that you could try the "Initial Layer Horizontal Expansion" Set to a negative number. It seems the effect you are getting is 'elephant's Foot' and that was designed to offset that. Give it a shot, it may help.

 

Unfortunately, that won't help here because the elephant's foot is not occurring on the initial layer but on the first spiralized layer. It's a Cura bug (or feature) depending on how charitable you are feeling. An obvious solution would be to reduce the flow at the beginning of the first spiral line and gradually increase the flow as the wall progresses. Unfortunately, doing that requires very small extrusion amounts to be used at the start of the spiral and would, in all likelyhood, not produce a reliable watertight bond between the spiral and the solid layers below. It would be very annoying to spend many hours printing kgs of filament only to find that the resulting object leaks out of a tiny hole at the start of the first spiral. Perhaps a reliable solution that produces less of a bulge would be to start not at 0% flow but, say, 30% flow and increase the flow to 100% as the first spiral layer progresses. That would reduce the bulge but, hopefully, still make a reliable join.

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2 hours ago, smartavionics said:

Unfortunately, that won't help here because the elephant's foot is not occurring on the initial layer but on the first spiralized layer.

Thanks for the correction 🙂 always good to learn proper things

 

2 hours ago, smartavionics said:

bug (or feature) depending on how charitable you are feeling.

🤣

 

 

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