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Disadvantages of smaller nozles ?

Posted by tmahring 
Disadvantages of smaller nozles ?
April 12, 2012 05:50AM
I have a more or less theoretical question: Are there any DISadvantages when using a small nozzle ?

To be more precise:
I currently have a .35mm nozzle on my makergear hotend. As far as I know, the recommended print settings for such a nozzle would be something like .2mm layer height and .45mm extrusion width. On my printer I increased this to .35mm height and .77mm width, to speed up my prints. Those values, to my knowledge, are what would typically be used with a .5mm nozzle - so I'm wondering if using a .35mm gives me any disadvamtages.

My prints turn out really fine, no problems in quality at all. I'm assuming the only advantage a .5mm nozzle would bring me is that i maybe could push the print speed a little highter - is that correct ?
Re: Disadvantages of smaller nozles ?
April 12, 2012 06:08AM
... smaller nozzles have better detail accuracies, but need more pressure to extrude and are slower in volume-per-time than bigger ones.

As you can change the extrusion parameters by extruding speed, travelling speed, stretching, temperature and material, you can vary the specific parameters of a nozzle over a wide range.

So it's on you, what specs fits better to your needs ...

Edited 1 time(s). Last edit at 04/12/2012 06:09AM by VDX.

Re: Disadvantages of smaller nozles ?
April 12, 2012 11:19AM
With a 0.5 nozzle I can do 0.48 layers and 0.72 width. I can't do that with a 0.35 nozzle because the filament comes out too small and if I do 0.35 layers with a 0.5 nozzle then corners are more rounded than if I did it with a 0.4 nozzle.

What size does the filament come out when extruded into mid air? That is more relevant than the nozzle bore.

Re: Disadvantages of smaller nozles ?
April 12, 2012 01:10PM
It extrudes .4mm into mid air.
I now changed the layer size back to .2mm H .44mm W. With .35mm layers I had massive problems with bridged. Seems i need to change my hotend to the .5mm nozzle to be able to print reliably at .35mm layer thicknes
Re: Disadvantages of smaller nozles ?
April 12, 2012 03:23PM
The cross sectional area that your filament wants to be is (0.4/2)^2 * pi = 0.13mm^2.

With 0.2mm H / 0.4mm W you have an area 0.088, so you are stretching the filament a little, hence it will bridge.

With 0.35mm / 0.77mm you are trying to make an area 0.27, so you are compressing the filament instead of stretching it. That only works if there is something underneath to press it flat. When bridging it will simply remain 0.4 diameter and be too long, so hang down.

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