Please, see this link http://youtu.be/LTJk07OVM7s. It is a foam cutter designed by David (dkj4linux) and I made one for my MPCNC. In this video it is direct powered by an external power supply.
Then, I would like to power this motor from the ramps 1.4. It needs a voltage supply about 9V and need to have the rpm Variable. Is this possible? Someone from the forum could give a help. I appreciate your attention.
With a brushless motor, you can use 12V directly from the ramps power supply to power your ESC, and then send a servo signal to control throttle. I saw something about servos in Marlin software, but I did not look in details.
I myself intend to try a brushed motor so that I could just hook it up to a fan output of my controller board (I use Rambo) wihtout any ESC.
Really, you don’t necessarily want the software to control the speed as much as you want the software to control the on/off, and have some repeatable control over the speed. If software is the easiest way, then sure.
The speed control depends a lot on the motor you choose. If it’s a hobby motor, then you can use a matched ESC. To control the esc, you could probably flash the marlin, but I’m not sure where that setting is. Alternatively, you could add another arduino (a cheap nano, or something like that) and program it to send out the PPC/PWM for the servo control, and maybe have another button or potentiometer that would control the speed from low to high. That could be as low as ~$10 for those parts. Depending on your skills, that might not be easier than the marlin approach.
Thanks, Jeff. I will try it and keep you posted. Take care. Silvio