1 Topic by spapadim (edited by spapadim 2014-02-24 15:29:34)

  • spapadim
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Topic: Nozzle diameter and free-air extrusion

Not sure why, but after swapping filament yesterday, I measured the diameter of the output.  My micrometer said .535mm (with zero variation axially, and just 3 microns radially), very consistent.  However, the nominal diameter of my nozzle is .4mm. 

What am I missing?  Is this expected?  This was free-air extrusion @100mm/min with filament that is very close to it's nominal diameter of 1.75mm (grey Octave ABS).  FWIW, my extrusion multiplier is .89 after calibration, which doesn't quite match either (.4/.535 = 0.75) -- this was manual extrusion, however, so multiplier is irrelevant.

2 Reply by elmoret

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Re: Nozzle diameter and free-air extrusion

Yes, it is normal.

http://en.wikipedia.org/wiki/Die_swell

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3 Reply by adrian (edited by adrian 2014-02-24 21:48:19)

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Re: Nozzle diameter and free-air extrusion

What elmoret said and linked to ... and yes it will be different between filaments based on their ingredient ratios and different based on the particular nozzle dimensions its shoved through and the speed you do that at ...

4 Reply by spapadim

  • spapadim
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Re: Nozzle diameter and free-air extrusion

Thanks! Upon further Googling, it also seems that is not very relevant when extruding *not* in free air (where hot filament immediately makes contact with other filament and it's shape is constrained).

5 Reply by ggunners

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Re: Nozzle diameter and free-air extrusion

Related question, when changing filament, what calibration steps are needed? Just extruder calibration and flow rate, or just flow rate?

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6 Reply by Tomek

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Re: Nozzle diameter and free-air extrusion

ggunners wrote:

Related question, when changing filament, what calibration steps are needed? Just extruder calibration and flow rate, or just flow rate?


I have always just calibrated flow rate. I dont see why extruder would be different per roll. Plus, flow rate will compensate if there was a difference.


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