Adding fan to RAMPS 1.4 and Marlin

peddiparth

Adding fan to RAMPS 1.4 and Marlin
September 23, 2012 12:05PM

Registered: 11 years ago
Posts: 72

I have a CPU Fan with 3 wires - 12v, ground, 5v (signal ?) to blow on the hot-end.
I am currently running it directly using PC power supply using just 12v and ground wires with a manual switch.

How can I hook this up to RAMPS 1.4 and control it with Marlin firmware?

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peddiparth

Re: Adding fan to RAMPS 1.4 and Marlin
September 23, 2012 01:40PM

Registered: 11 years ago
Posts: 72

I will be happy with instructions to get a generic 2 wire fan to work with Ramps 1.4 (h/w connections) and Sprinter (or Marlin if possible).
I do not see Fan connections in RAMPS 1.4 wiki page.

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johnoly99

Re: Adding fan to RAMPS 1.4 and Marlin
September 23, 2012 01:50PM

Registered: 12 years ago
Posts: 216

Hook the fan up to D9 i believe on the ramps shield. You can turn the fan on/off and measure voltage at the D9 connector and see if it is D9 or maybe it was D8? Not at a printer at the moment. Its one of the three connections.

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peddiparth

Re: Adding fan to RAMPS 1.4 and Marlin
September 23, 2012 02:02PM

Registered: 11 years ago
Posts: 72

Thanks johnoly99 for the hint.
I was going about it the wrong way. I was thinking in the direction of connecting the 12v directly from PC power supply, and finding a 5v PWM connection for controlling the fan.

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johnoly99

Re: Adding fan to RAMPS 1.4 and Marlin
September 23, 2012 02:31PM

Registered: 12 years ago
Posts: 216

Ahh, D9 is pwm from the board. M106 S(0-255)

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orcinus

Re: Adding fan to RAMPS 1.4 and Marlin
September 23, 2012 03:43PM

Registered: 12 years ago
Posts: 156

D9 is the 12V PWM from the board! Don't connect the fan's PWM pin to it or bad things might happen winking smiley

Just hook the 12V and GND wires from the fan to D9 on RAMPS.

Then use M106 S[0-255] for fan on / speed, and M107 for fan off, as johnolly99 said.

Edited 1 time(s). Last edit at 09/23/2012 03:52PM by orcinus.

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peddiparth

Re: Adding fan to RAMPS 1.4 and Marlin
September 23, 2012 06:11PM

Registered: 11 years ago
Posts: 72

I checked D9 and it had 12V to ground. I connected the 12v & ground to D9 connectors. The fan now works ok.
Does the option for FAST PWM really work in Marlin? I noticed that my hot-end fan does not run under 70% power in the PWM.

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orcinus

Re: Adding fan to RAMPS 1.4 and Marlin
September 23, 2012 08:54PM

Registered: 12 years ago
Posts: 156

If it doesn't work < 70%, it quite probably won't work with fast PWM either, although it might help a little.
On most fans i've tried, if it doesn't work <70%, with fast PWM it will work to maybe as low as 60%, but with a lot of noise and a very very sharp drop in RPM from 60 to 80.

So not really very usable.

You can try adding a capacitor across D9 (in parallel with the fan). A resistor in series too, probably.
That should iron out the PWM a bit.

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NewPerfection

Re: Adding fan to RAMPS 1.4 and Marlin
September 24, 2012 12:50PM

Admin
Registered: 15 years ago
Posts: 1,470

3 wire fans do not have a PWM pin. The third wire is for RPM feedback. 4 wire fans do have a PWM pin.

All the fans I have tried run well down to about 20% PWM.

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orcinus

Re: Adding fan to RAMPS 1.4 and Marlin
September 24, 2012 05:30PM

Registered: 12 years ago
Posts: 156

You're right, my bad.
That should've said "tach pin", not "PWM pin".

Regardless, though, point is, if you hook 12V to anything but 12V and GND, it won't work (unless you count production of magic blue smoke under work).

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peddiparth

Re: Adding fan to RAMPS 1.4 and Marlin
September 25, 2012 11:06AM

Registered: 11 years ago
Posts: 72

Got myself an inexpensive pair of tiny (20mm) fans from CompUSA for $7. With 2 wires, no doubts this time smiling smiley

Thanks for your very helpful responses.

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