Fans & Part cooling

Hi,

Ive been trying to begin printing gears recently,

Running a Nophead Prusa (about 1 year old) but with full LM8UU upgrades and upgraded Z couplers

Printing using an original Wades and a J head MK 4 B and Sanguinololu, running Marlin

Host is Pronterface and Slicing with Slic3r 0.71 if that's of any relevance, using Faberdashery Purple PLA

The gears look workable in some light but especially where it moves between one and another it falls over and i get a molten mush

My question is How can i improve this, The set ive been trying to print [www.thingiverse.com] (triffid_hunters set)
suggests using a fan, but what sort of fan how big / how many CFM? Where do i put it?

Do i want it controlled by Slic3r (ive re assigned pin 4 (spare PWM to control it via M106) so thats an option

ive not yet tried running with a fan at alll but the only spare i had (large old 80mm one was wining untill the PWM exceeded 200




Slic3r Settings:
bed_temperature = 65
bottom_layer_speed_ratio = 0.5
bridge_fan_speed = 100
bridge_flow_ratio = 1
bridge_speed = 50
cooling = 1
disable_fan_first_layers = 1
fan_always_on = 0
fan_below_layer_time = 60
filament_diameter = 2.82
fill_angle = 45
fill_density = .8
fill_pattern = rectilinear
first_layer_bed_temperature = 65
first_layer_temperature = 180
infill_speed = 100
layer_height = 0.4
max_fan_speed = 100
min_fan_speed = 35
min_print_speed = 10
nozzle_diameter = 0.5
perimeter_acceleration = 25
perimeter_speed = 80
perimeters = 1.
retract_before_travel = 2
retract_length = 1.5
retract_lift = .1
retract_restart_extra = 0
retract_speed = 30
slowdown_below_layer_time = 15
small_perimeter_speed = 30
solid_fill_pattern = rectilinear
solid_infill_speed = 100
solid_layers = 2
temperature = 170
travel_speed = 200

Try slowing down. I print gears at 20mm/s perimeter and 50mm/s infill with marlin. I would also reduce the retraction length as I find if its that high I get bumps.

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Try printing 4 at once I found doing one was giving me problems but doing 4 at once solved the issues I had, but then I went to aluminium gears and gave up on printed ones

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Experimenting in 3D in New Zealand

Thanks,

Ill give these a go,

Busy week ahead so don't expect a response before next Sunday but your ideas are appreciated

NelsonRap: im printing the big and little together already to attempt to mitigate this, could try printing 2 sets i guess, but mopst of the issue appears to occur on the faces opposing each other on the print bed,

Ill try and post some photos when i get to it

Rob

I (after finally getting it to work) have been using fan cooling with RAMPS 1.4 and Slic3r. I've printed a single small wades gear no problem. Definitely have to decrease the speed and retraction values like mentioned above but cooling on Slic3r will decrease the speed anyways. I only use 85% max on my fan because it tends to drop my bed temp too much.

Prior to using cooling I had to print 4 or more so that they didn't melt into themselves. Now, one is no problem.

I had the same problems with gears and small items like the Gregs Extruder Guidler. I won't want to print a bunch at one time just to get one good part. I took the advice on the IRC and added a fan. I asked all the same questions .. how big .. how many CFM ..

The answer is take whatever fan you have laying around and slap it on .. I have attached a photo of my ghetto fan mount modeled off one of the very esteemed IRC members .. don't overthink it ..

It works. I just hooked it up to my spare RAMPS extruder D9 .. changed a couple of pins in Config.h and away I went. I pretty much leave my fan running full blast after the first layer is done on most prints. Great results. Between fan and better temp control I get great small features in my prints now.

Thank you All

Just had a bash at one single small gear, with a even more ghetto fan (seriously shameful) - photo attached

The news is good, Print was looking awesome but it popped off (to much fan I think)

Ill throttle back and try again but not tonight as im off out in a min

But to recap slow Feeds feeds and the fan and there isn't much stopping me now

Thank you very much guys,

Ill post a how to at some point on adding a fan to Sanguinololu in the appropriate forum

Thanks again

Rob

Edited 1 time(s). Last edit at 04/17/2012 06:33PM by ijmok.

ijmok Wrote:
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> Ill post a how to at some point on adding a fan to
> Sanguinololu in the appropriate forum
>

I look forward to this as I've been thinking about doing the same thing but don't have a clue where to start!
Cheers,
Dave

Edited 1 time(s). Last edit at 04/17/2012 06:57PM by davejones.

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You should mount a fan on your extruder and make a duct so it blows exactly at (or ideally just below) the nozzle. I used a piece of sheet metal to mount a corner of the fan and then foil tape (more rigid than duct tape; it's my new favorite tape!) to make the actual duct. Looks ghetto as hell but works well and doesn't cool the bed down much at all.

I am not a big "fan" of mounting a fan on the extruder. I try to add as little weight as possible to the x carriage.

A small 40mm fan weighs nothing. A directional fan duct will keep the cooling mostly on the freshly extruded plastic instead on the print bed, decreasing the likely hood of the object popping off. Check out Fan Duct This is the one I use on my Prusa. Still able to print 80mm/s reliably .