Layer fan causing poor prints???

So good afternoon folks :) I have had to step back a couple of weeks from printing (vacation, bad heater in my hot end etc). All that is fixed..

I have printed of cloughs layer fan (and his auto leveling, and x carriage and hot end cooling etc) and its great.
However, when i run it, the print quality is noticeably worse (PLA).
I have 4 test prints .
1. 100% fan
2. 60% fan
3. 30% fan
4. 0% fan

the test cube 3 and 4 look a lot alike, because there isnt much air blowing at 30% i dont think.

The ones that are running more air, seem to be much lower quality.

None of them are as good as i had it printing before making the mods (perhaps i have a slight carriage bolt loose or something). but either way, there is a distinct difference in print quality.

from left to right 100 60 30 0

http://i1132.photobucket.com/albums/...ps0wde1upo.jpg


any idea why this would be?

hmm not sure, its curious.. how are you adjusting the fan speed?

Simplify 3d has the speed set inside their slicer. it is working, because the fan speed is the only thing i changed, nothing else.
:)

I noticed that before, where do you have your fan plugged into on the board? or this to work. I have always just had my fans plugged in directly to my power supply

Thats all fine and good, but i dont want to use the fan all the time, and i want to be able to use it only when bridging, or at certain points etc... in to the PS doesnt give that flexibility.

They are two different fans.... The fan that goes on your extruders cooling fins should be connected to constant power..always on...the parts cooling fan is an additional fan that is mounted close to the extruder tip to cool the parts while bridging..ect...that one is controlled via slicer ..

Quote:

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Originally Posted by dunginhawk

Thats all fine and good, but i dont want to use the fan all the time, and i want to be able to use it only when bridging, or at certain points etc... in to the PS doesnt give that flexibility.

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and thats the exact setup i have.
1 fan for the cooling of the hot end and one for layer... im not a complete noob lol

http://i1132.photobucket.com/albums/...psjhbndzd5.jpg

is there anyone out there that can help deduce the issue here?
it actually happened when i first attached another cooling fan, then went without for a while while i set up ABL and the fan behind the hot end (cloughs). i just recently printed cloughs layer fan again and see the quality suffer.

Is there any test print out there that would adequately tell if the fan is on well enough for PLA? maybe 100% is too much and 30% is enough to not affect the quality much, but still cool enough.
any ideas?
thanks

I don't know how much I can help you as I am new to the Prusa but I have a little experience with 3D printing.

Do you know what cfm your layer fan is rated for? If it is pumping out a high cfm like 8-10 for a 40mm fan then I can see why the high fan rate is making your prints worse. You want the layer fan to help cool the PLA but not harden the PLA, too much fan can do that.

Also, I would not have the fan at a high speed unless you are bridging or making something with a small volume.

Most that have had issues with the C42 print cooling shroud have had the issue of little outlet airflow, not too much. Rotary fans don't do well pushing against pressure, and the small outlet nozzle creates a large amount of backpressure that causes most of the airflow to just leak back out around the fan blades. The shroud didn't do well with any of the fans I had on hand; I didn't purchase the fan Clough specifically recommended for it.

thats interesting... the outlet nozzle on the one i printed is pretty good size... not tiny like some of them. im getting some decent air flow. I tend to think its a factor of too much flow vs too little. Ill run some bridging tests or something to figure it out... it bugs me though :)
thanks

Ive just recently started printing in pla and have been using the C42's extended fan shroud with the makerfarm fan. It doesn't blow a lot of air over the printed part but I haven't noticed any print quality issues. Im actually rather impressed with pla and might start using it instead of abs. Abs gives me layer separation issues for larger prints.