attach a fan

hi all
have bought a small 60mm computer fan to cool my layers as i print.
have noticed u can control the fan and heater bed (haven't got one of those) from the software (see attached).
so my question is where do i connect the fan so that i can control it from the software.
i am not really up on the electronics . have attached a photo of my circuit board. there seems to be one connector left
near the usb cable - perhaps this is where i connect the fan (not sure where the heater bed would go).
i currently have the fan just wired into the supply but would love to control it thru the software mainly to'
be able to turn it on after layer 1.
thanks for any help,
regards,
roger

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

What kind of electronics is this?

In general, you need a MOSFET to drive a fan. Either you have a third one on your board or you need a solution like the SevenSwitch (see wiki). If you have that, define the signal pin for your fan in the firmware and things should start working.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

no idea which electronics that is

has it got a connector for a heated bed? as if it has you can change the PIN setting in the firmware so that the fan runs on the heated bed connector

other then that you can just baby sit the print for a while and after 3 layers just connect your fan to 12V and leave it run.

I run my PLA with a fan on full speed after 3 Layers around 6 inches away from the head.

Also have the fan mounted in a way that it blow across the top of the print BUT does not touch the bed (dont have it pointing down!)

personally i would get a cheap arduino mega from china and get a ramp 1.3 or 1.4 board (no difference between the 2 other then 1.3 is easier to solder) that has enough mosfets for extruder, fan and bed and also other things like LCD SD Card etc

Thanks all - will need to find out a bit more about the board by the sounds.
Enlightx,
Am happy enough to do the fan manually for now - thought it might be an easy thing to do to add the fan.
DO you have a heated bed?
Why 3 layers and not just the first? Don't you get the layer 2 and 3 being sticky if you don't turn the fan on? What temps do u use?
I am getting a bit lost trying to get my parts to stick to the bed - is only 35mm square at the base (using fill of 1.0 later on). It warps and then pops off at about 5mm high. [Edit: I suppose layer 2 will be ok as layer 1 is put down slowly and should therefore be dry for layer 2]
I have kapton tape on unheated bed.
Do you have suggestions on which direction to experiment with?
ie. should i raise the temp first or use blue tape* or clean the kapton or all of the above.
I have tried to raise the temp to 210 for the first layer but Repitier seems to just sit there and not do anything (i extrude at 210 and then hit run - i think it is waiting for the temp to settle down - seems to jump around from 208 to 212 a bit). (At 200 I do the same thing and it starts straight away). Might have to raise this as a seperate post unless you know of a simple thing I am doing wrong.
What about rafts - don't seem to have them in Slic3r. Can you add you own manually to the part? Or grooves to the bottom of the part?
What causes warping etc is it the amount of plastic on the first layer (ie. solid) or is it how further layers up are done ie. solid layers instead of 0.4 infill?
Sorry am just all at sea with this...
Please help
Roger.
* Have just bought some blue tape - hope it is blue duct tape not blue masking tape. Whoops looks like it is the masking tape - back to the shops.

Edited 4 time(s). Last edit at 11/13/2012 09:45PM by rogerw.

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

perhaps the temp thing is the same as "Slic3r Gcode not starting print" post (how do i make a link to that)

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

i have a GEN6 board - this one [reprap.org].
The pin specification (http://reprap.org/mediawiki/images/1/1a/Gen6_Electronics_pin_specifications.pdf) seem to have a 12C ? extra connector - not sure what that is for. (Heated bed perhaps). Think this is the spare one in the photo.

Edited 4 time(s). Last edit at 11/13/2012 08:28PM by rogerw.

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

thanks Traumflug
the sevenswitch [reprap.org] thing looks interesting.
are signals from the GEN6 board to other boards sent via the RJ45 connector???
roger

Edited 1 time(s). Last edit at 11/13/2012 08:31PM by rogerw.

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

I would just hack it and connect to a pair of wires to your psu and run full time. But for my RAMPS setup, I connect to the spare MOSFET terminals.

i have spoken to the people i bought the machine from and they reckon i should be able to plug the fan in so will give an update for others who have a GEN6 board

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.