Part Cooling Fan Shrouds - Who Needs 'em?

I have noticed that on Thingiverse a large number of posts are for fan shrouds for part cooling.

I have printed some of the fan shrouds and they produce far less air flow than just a plain old fan.

I have been 3D printing for about 3 months, and the only time I have found that I need air blowing on the part is for small layers where the plastic does not set before the next layer is printed.

I just use a 5" USB Fan located at the side of my printer, blowing across the build platform, which seems effective to me.

Is there another situation where we need to run a fan?

Why not just use a fan without a shroud to cool the recently extruded plastic instead of a airflow reducing shroud?

Any other comments?

Well I found part of the answer. If you have too much generally applied cooling, the heater in the nozzle assembly cant keep up with the demand. I put my USB fan too close and the bed temp and extruder temp would not reach the set point. I could not explain why when I raised the extruder, It reached temp and lowered it it would not. thought loose temp sensor wire or something. called in my wife and she said, is it that fan! duh!

for PLA only I use a desktop cooler fan directed at the printer. Does wonders.

I don't knowhow efficient it is; but it is to achieve uniform distribution of cooling around the print. With just one fan you only cool the plastic from one side leading to possible irregularities.

Quote:

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Originally Posted by mAcademia

I don't knowhow efficient it is; but it is to achieve uniform distribution of cooling around the print. With just one fan you only cool the plastic from one side leading to possible irregularities.

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The plastic is cooled as soon as it is laid so it does all of the plastic.

A fan housing/duct around nozzles is Not Needed !
And they really 'Get in the Way' !

But the X & Y stepper-motors, in some printers, Do need a fan !
(depends on printer design and room-temp mainly, need Good air flow around them)