Ramps 1.4 and Fans wiring.

Hi all ! First, I wired my hotend's fan on the D9 output, as suggested on a german website. That was stupid, because when the fan control is on (and the fan is running low or stops), the filament clogged into the hotend. Hopefuly I early understood that in my starting steps. The right place to be wired for that fan is directly on the power supply. Then I mounted auxilary fans to cool-down the work, on D9 outpout, of course. And all that worked great. And all of the outputs are in use.

So, what about if you want to switch to multiple extruders ? The D9 output is now for the second extruder heating. The hotend fan still goes on the power supply. But where to wire the fans to cool the work ? Is it still possible with the RAMPS 1.4 or is it necessary to switch for a better board ?

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

Personally I would use a 4-wire PWM-controllable fan, with the red and black wires connected to +12V and ground, and the PWM control input wire connected to one of the spare Aux output pins. However, I don't know whether Marlin firmware supports this configuration. Also, some PWM fans only go down to 30% speed under control of the PWM input and not fully off; so depending on the fan, you might not be able to turn it off completely using this arrangement.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

There's more than a few unused digital pins on the RAMPS board, including at least one PWM in AUX4, not to mention any of the servo pins are also PWM. I have a E3D hot end wired to pin 43. Marlin is configured so that pin 43 is turned on when the hot end is 50 degrees C or hotter, then shuts off after it cools to below 50 degrees. There are multiple designs (example) for a fan (or anything else) controller to allow you to use voltages and currents other than what the would otherwise be available directly from the pin. I personally don't think PWM control of the fan is necessary for cooling the hot end. Just run it full speed on or off all the time...I've never heard of someone complaining because their cold end was too cool. It's the bed fan that may need to ramp up and down.

Edited 1 time(s). Last edit at 12/03/2014 03:34PM by cdru.

Or you drop one of these [www.geeetech.com] onto the servo pins

Both solutions are interesting, and have pro and cons. For example if you want in the same time a full display+card reader and an auto level sensor. For the display there's no other choices. But you can build a sensor for auto bed leveling without the use of a servo motor. Maybe it's the best solution, especialy because you can buy the plugin.

Then I believe that would be a question of pin assignement in Marlin ?.

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

Quote
Zavashier
Both solutions are interesting, and have pro and cons. For example if you want in the same time a full display+card reader and an auto level sensor. For the display there's no other choices. But you can build a sensor for auto bed leveling without the use of a servo motor. Maybe it's the best solution, especialy because you can buy the plugin.

You could just as easily run the pre-built board off of some jumper wires. The board is a bad design from the standpoint that it takes up all 4 servo slots, but only uses 2 of the PWM pins (D11 and D6). Plus it doesn't use the 5V pins it's taking up as well. They could have made the connector 2x3 pins and accomplished the same though although it might not be as stable with the narrower connector. But at least you could still use all your capability. Even pass through pins would have work.

Another option is this (ebay listing on the page if you want an assembled version).

Interesting solution cdru, I start to understand how all this works. Thanx

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)