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5.3 Calibrating Your Axes
Now you must calibrate your machine. To get your units perfect, you must calculate them manually from your machine
specifications. However, you can get them pretty accurate if you use the calibration wizard (see Calibration Wizard
section).
5.3.1 Manual Calibration
You need to calculate how many steps there are per inch and the maximum velocity of your system. If you purchased
motors from MachMotion, use the table below as a reference.
Motor Type
TECO
Mitsubishi
Steppers (10 micro-step)
Table 4 Motor Encoder Counts
Calculate the steps per inch and velocity using the steps outlined below.
1. Calculate your gear reduction using the number of teeth on your pulleys and your gearbox ratio. If your motor
is directly driving your axis, then your gear reduction is 1. Otherwise use the formula below.
Gear Reduction = Screw Teeth / Motor Teeth * Gearbox Ratio
1. Now calculate the distance one motor turn will move your axis by taking the ball screw pitch and dividing it by
your gear reduction.
Distance of One Motor Turn = Ball Screw Pitch / Gear Reduction
1. Next calculate the number of steps per inch. Find the number of encoder counts for your drive (which can be
found on the motor specification sheet or in Table 4) and divide it by the distance of one motor turn. This
gives you what Mach3 calls your "Steps per."
Steps per = Encoder Counts / Distance of One Motor Turn
1. Finally you can calculate your velocity by multiplying your motor's RPM by the distance of one motor turn.
This gives you your velocity in inches or millimeters per minute.
Velocity = RPM * Distance of One Motor Turn
For example, if you are setting up a 3000 RPM TECO motor with a ball screw pitch of 5 TPI (0.2" pitch) and ball screw
pulley with 36 teeth and a motor pulley with 18 teeth, calculate it as follows.
Begin by calculating your gear reduction. Take the number of teeth on your screw and divide it by the number of teeth
on your motor. In this example the axis has a gear reduction of 2 (36/18).
Now calculate the distance one motor turn will move your axis by taking the ball screw pitch and dividing it by your
gear reduction. In this example one motor turn will move the axis 0.1 inches (0.2"/2).
Next calculate the number of encoder counts per inch (steps per). Find the number of encoder counts for your drive
and divide it by the distance of one motor turn. In this example the steps per inch is 100,000 (10,000/0.1).
Finally, you can calculate your velocity by multiplying your motor's RPM by the distance of one motor turn. The
velocity in this example is 300 units per minute (0.1*3000).
Now you are ready to enter these values into the Mach3 software. Select Config on the top menu bar, then Motor
Tuning. You should see the Motor Tuning and Setup window as shown below.
Encoder Counts
10,000
131,072
2000
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