Friday, January 28, 2011

Plotter project Notes

These are resources for my next project. Building a CNC xy plotter using an Arduino and some old steppers and printer parts I have.  I have not decided yet if it will be a paper + pen plotter or something more interesting like an eggbot or a sand table.

The endpoint will either be a pen or some sort of simple cutter. The problem with the cutter is the that it takes a little more precision and has a higher cost per mistake if I jam it into a table or something else goes awry. Still the learning is in the doing and mistakes are part of the fun.

http://www.tigoe.net/pcomp/code/circuits/motors/stepper-motors

The system will have 3 axis of control for starters with limit switches on both travel ends of each axis. This gives me six switches to read from. I also want to put some debugging lines using LED's so I know what should be happening even if its not actually doing anything. There will also be 2 calibration switches for the head position. The last (or first) major feature is a master kill switch which will terminate all the action on the plotter but will not kill power to the Arduino.

The overall features will be:

UP_X, UP_Y, UP_Z - Moves the Z axis to the top of its travel (Is 0 best as the top or the middle of the travel?) Away from the work piece.

Home - Returns the head to (0,0,0) in an orderly way. slowly.

Calibrate - Measure the dimensions of the cutting head.

CutterON and CutterOFF - Power up or down the cutter head. (Not used for a pen obviously)

LOAD - Measure the load on the cutter.

RUN - Start the current cut/draw script.

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