Fan - main purpose?

So FAN. What is the main purpose of it. As I see cooling down plastic quickly, right? Improves quality I guess?
Just realised that since I got FAN replaced, I've put it wrong direction, so instead of pushing cold air on nozzle, it actually taking air from there away.
The funny bit, is that I've not noticed a difference really.

PS. going to put fan back to push cold air on nozzle now, and print some more (need to wait till current print finish).

Could someone experienced clarify this please?

Max

The main reasons for that fan are to cool the upper aluminium block, and stop heat from the hotend from melting the filament too soon, and to stop the heat from melting the plastic bracket and X carriage - RRP put the vents at the bottom so that it would help with cooling of the model (particularly for bridging) - whether it sucks or blows it should still draw air over the heatsink and cool the aluminium block to some extent, but I have a hunch it's going to do that more efficiently if it's blowing (I might be wrong on the cooling efficiency, I often am)

Cheers

Ray

Edited 1 time(s). Last edit at 02/23/2014 12:26PM by rayhicks.

Hi Max / Ray, I was thinking the other day that if the fan sucked instead of blew it would probably reduce warping in large prints.
Just a hunch, I haven't tried it, and I'm printerless at the moment, until I get the mods done on mine when I get home.
(Roll on Wednesday...... )....
One of the mods will be to add a couple of tooth paste tubes flip style caps as vents to the top of my fan ducting so I can let the
air go up rather than down... It'll be an experiment, and if it fails I'll just leave the caps shut..... Nothing ventured nothing gained.....
I wonder if any one has tried using a water cooling system instead of a fan.. I could just see the silicon tubes thrashing around like
a Lobsters tentacles.

Kim

Edited 1 time(s). Last edit at 02/23/2014 03:59PM by KimBrown.

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Hi Kim Brown

Water cooling : look here [blog.think3dprint3d.com]

I want one

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XB70

Sounds like a plan Kim - I drilled a hole in the top of mine, sawed off the lower vents and blocked the remaining lower holes with tape - this works great with ABS, when I've run PLA recently (to do some long wide prints that pretty mcuh fill the bed) I resorted to PLA, and it worked OK for those too, until I sped things up - PLA pretty much needs some external cooling I think, preferably a speed controlled external fan which can be off to start with then ramped up for higher layers (and bridging) which slic3r etc cater for, but the ormerod doesn't seem to as yet. Maybe reversing the fan would have saved some surgery Definitely a good idea to go for a vent that you can bypass for comparison purposes.

I've had a go at getting some stuff together for water cooling - ideally I'd have a peristaltic pump delivering the water, I looked at putting one together from scratch, but the torque on cheap geared motors (and steppers) just isn't up to it - I've got some used continuous duty peristaltic pumps at work, but they're pretty costly (roughly the price of an ormerod) and better off refurbished and put to work in their original role really. I talked with markbee about this and I think he was intending to try an aquarium pump - these have great no-load water throughput, but can't make much of a head - I'm not sure he's pursued this though, he seems to have a lot on the go atm. Peristaltics are attractive to me since they can deliver a relatively small amount of liquid, but at a reliable flowrate over quite a range of pressures - the low volume they'll deliver is fine when you compare the heat capacity of air and water though Maybe gear-based windscreen washer pumps would work OK, though I'm pretty sure they're not rated for continuous duty.

I'm 70% committed to designing my own extruder (with better heat coupling to the nozzle tip by using a brass tip screwed into the aluminium block, and no insulation within the tip itself, a heat barrier based on plastic and stainless, rather than stainless alone, and not relying on threads for coupling (my hotend bits tend to loosen relative to each other with time, trying to tighten one bit affects the others, and the lower heat block can't turn unless you dismantle the whole head) so I'd use clamping - if I get to 80%, I'll look more into using water cooling too...

Cheers

Ray

Hmmmmm be careful messing with the HotEnd, I have a real deep burn on the tip of one of my thumbs trying to
get the B&**er apart..... Ouch was the second thing I said..... I had to do it hot as the plastic had glued it togeather....

As for pumps, the thing is you don't need a pump that will give a high head of water, as long as you fill the supply and return
pipes full of water.... The weight of the water coming out will equal the weight of the water going in, so the only thing you
have to get over is the friction of the water in the pipe. Windscreen washer pumps are good, but over heat, you'd need
to wrap a coil of tubing around the motor to cool it down. If you have a decent model shop around MFA (Model Flight
Accessories) produce a gear pump that is good, but again, for long running you would need to cool it. If you can get hold
of a tiny aquarium centrifugal pump then that would be ideal.... My young lady has a fish tank with tropical fish in, well Had
is probably more precise... Its down to one fish now. Then shes giving up with them...hihihihi I might win a pump here....
At least they are very quiet, run for as long as you like and don't use much power. You can block the outlet of a centrifugal pump
and it with use very little power, cos it's just spinning the water in the pump. Where as a peristaltic pump will use loads as it's positive
displacment.

As for the air vents, I was brushing my teeth earlier, and I just thought the tooth paste tube cap would be ideal with it's flip lid....
Going to have to brush my teeth 8 times a day now to use the tube up......

I liked that 4 or 5 J head, then I saw the result of the ooooze from the other nozzles and think there must be a better way...
My J Head seems fickle.... I zero the head, and there's ooze coming out... I start to print, and it's normally halfway round the
first loop of the skirt before it starts printing.... I also suffer from threads, but I think Ian suggested that I might be running the hothead to hot
soooooooo WHEN I get the printer back together I'll try running it at a lower temp.

Oh and the other thing I had (which was how I burnt my thumb), was that I had plastic coming out between the nozzle and the coned nut,
which I think means I must have got some PTFE in the nozzle... I have a replacement coming, and I'll sit the old nozzle on the
gas cooker to burn the plastic out when I get it off. Two more days to go then I go home, and I can do some mods to the printer

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Please send me a PM if you have suggestions, or problems with Big Blue 360.
I won't see comments in threads, as I move around to much.
Working Link to Big Blue 360 Complete