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JohnInOttawa

Fine tuning line width for small rectangular pyramids

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This thread is related to my nylon printing 'adventure'.  The part of the print I am struggling with is an upward facing gear-toothed circle.  It looks like the print is suffering from severe overextrusion and the nozzle is dragging material out to the perimeter.  Replaying the layer view in Cura, I am starting to wonder if the line width required for these gear teeth is narrower than I have set.

 

I'm using a 0.4 nozzle currently, have adaptive layers in use per a suggestion here and that has improved things somewhat.  Base layer height is set at .05 and width at 0.4.  When I look at how it tries to print that, I can imagine why there is excess filament.  When I increase line width to 0.45, it looks better in Cura.  I imagine it will slightly underextrude and that might offset whatever is going on.

 

Of course, if underextrusion is what I am doing, I would rather not do that do the rest of my print.  Can I set up a line width change to start at a specific layer?

 

Thanks once again...

John

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Could you post images (screendumps) of the design in Cura, and photos of the results? The photos with ruler, so we can see the dimensions.

 

I haven't printed with nylon yet, but there could be other things involved, such as insufficient cooling in a tiny model, so the model can't solidify. Or overextrusion due to slowing down in corners, when the internal pressure can't immediately be released, etc.

 

For PLA, printing slow and cool usually helps. And printing a dummy tower next to very small prints, so the nozzle is away from the model, allowing it to cool, and so that printing-time per layer is equal for all layers.

 

As said, this works for PLA and PET. But I don't know if it also applies to nylon (if too cool, you get poor layer bonding).

 

But of course, it could be something else too.

 

Below: a few images of the dummies: the basic concept, and a real model.

 

dummy_inverse_block6.thumb.jpg.2bdb2396588983363b48127ee12d8174.jpg

 

dummy_cutout2.thumb.jpg.750722bab5fa1c22a5e38d2a5717ab5b.jpg

 

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Thank you.  Your comment about slowing down in corners resonates - these are small teeth and corners are exactly where things are getting messy. 

 

I'll try to explore ways to change how that path is laid down.   If it was CNC I would know how to change that toolpath, but I don't have that skill or knowledge (yet) here.  Fortunately, there are some smart people to ask here 😉

 

For a dummy tower, is that simply a matter of creating a separate STL and importing it to Cura, or can I do that within Cura itself?

 

Thanks again!

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