Centroid Acorn Plasma Users Manual Beta CNC12 v4.65 rev6
The Plasma Machine Setup Sweet Spot for nice cuts and smooth action.
Mechanical Sweet Spot.
1.) Overall Turns ratio value in the range of 1 to 2 turns of the axis motor per inch. Mechanically build the machine
so that one turn of the axis motor yields 1” of travel (25mm) or less. All rack and pinion driven machines will require
a belt reduction or gear box to achieve this. Typically in the 3:1 to 5:1 range depending on the rack and pinion
chosen. Note: Direct driving the pinion with the axis motor results in poor cuts. Z axis Overall turns ratio sweet spot
is in the range of 2.5 to 5 turns per inch.
2.) Motors sized properly to move the machine without risking losing steps or stalling.
3.) Free and easy axis motion with no sticky spots or other problems, when the axis motor is disconnected moving
the axis back and forth by hand should be smooth, consistent and easy.
4.) Machine is rigid enough not to shake or flex when moving at typical cutting speeds.
Electronic sweet spot
1.) Steps per rev set in the 1600 to 3200 range for stepper motors. Both the Acorn Wizard and the Stepper drive
should be set to at least 1600 steps per revolution. 2000 is a good steps per rev value to use. Do not use values
below 1600.
2.) Stepper motors are required to have proper matching power supplies and AMP settings on the stepper drive. Just
because the motor works does not mean that it has been optimized for smoothness. No amount of Centroid G code
smoothing will overcome a stepper motor that has too many amps being pumped into it or has its phases not wired
properly for the voltage of the drive power supply being used. Review https://www.geckodrive.com/support/step-
motor-basics.html for details. Better yet use AC brushless servo motors (Clearpath, Estun, Delta etc) or closed loop
stepper motors (Leadshine, Stepper Online) instead of open loop stepper motors.
Page 7 D:\Keith Documents\centroid_acorn_plasma_users_manual_draft27.odt rev27 3-15-22
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