Newbie: Spindle control 0-10, PWM, ???

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19 Dec 2009 05:15 #1358 by dmerriman
I'm looking at putting together my own little system (hobbyist level), and can't see any kind of control over spindle other that 0-10V and PWM -- or am I missing something?

I've got a number of stepper motors, and it wouldn't be any big deal for me to gear one of them down to some arbitrary number of minutes (or even seconds) of angle per step; is there any reason I can't/shouldn't do this?

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19 Dec 2009 05:27 #1359 by dmerriman
Let me add that what I want to do is have a CNC that can do X/Y/Z, with the capability of serving double-duty as a CNC lathe (which is what I'm calling the spindle).

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19 Dec 2009 05:30 #1360 by cmorley
The component stepgen can be used to control steppers in velocity mode instead of position mode.
Velocity mode commands the stepper motor to rotate at a constant speed instead of a position.
I don't know of any sample HAL files to follow. Stepconf won't set this up for you.
You could use Stepconf to create a configuration then hack the HAL file to add a step generator for the spindle.

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19 Dec 2009 05:43 #1361 by dmerriman
For the interface between EMC2 and the motors, I'll be hacking together a microcontroller-based interface, so I can do pretty much whatever needs to be done (I'm a computer geek taking a walk on the wild side :woohoo: ).

If I'm understanding you correctly, stepgen will put out some command telling the spindle how fast to go; it would be up to me to figure out how to "translate" that command (absolute speed? value from 0 to some maximum?) into the appropriate stepper speed to produce the specified RPM.

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19 Dec 2009 12:30 #1362 by BigJohnT
Stepgen puts out a step pulse and a direction pin.

www.linuxcnc.org/docview/html//hal_rtcomps.html

John

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19 Dec 2009 15:49 #1363 by dmerriman
Okay, I'm tracking with you now.

Thanks very much for your help!

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