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VFD - Spindle Calibration

These instructions apply to all VFDs where the spindle is controlled through the Mach4 Control Spindle tab

Overspeed a Motor

If you want to command your spindle motor or grinding wheel to go faster than the base frequency, command the spindle to go max RPM and use a tachometer to measure the speed. Then use the following formula to calculate your new Max Output Frequency (Hb105):

Desired Max RPM * Current Max Frequency / Current Max RPM = New Max Frequency 

For example, if your Current Max Frequency is 60 and you measure the spindle runs 1030 RPM but you actually want it to go 1515 RPM, calculate your new Max Frequency as follows: 

1515 * 60 / 1030=88 Hz. 

Make sure to recalibrate your RPM feedback and your spindle speed as both shown below. 

Calibrate Spindle Speed

Does your CNC control need it? Yes - it needs to be accurate enough to meet your needs. 

  • The rated speeds and feeds for your tools and materials should perform as expected.
  • You should have comparable performance across all your machines when running the same spindle speed. 
  • Accurate spindle calibration enables you to make cleaner and more accurate cuts – improving the quality of your final product.
  • Scheduled preventative maintenance should include verification of the accuracy of the system, including the spindle speeds. 

This documentation focuses on knee mills as a common example and is adaptable to other machines. 

Spindle control methods

This is all configured during the installation. This document assumes that the parameters for the motor have been correctly entered, and the VFD and motor are operating correctly.  The last step in the spindle setup will be speed calibration.

Analog 0-10v from the Apollo III is managed through the face of the drive with Yaskawa Drive Wizard software. The wiring configuration is documented here in the 2000 Series Apollo III Operating Manual.

Ethercat VFDs are configured through RapidPath. RapidPath sends a speed command to the VFD – often an RPM command. If that implementation is correct, you should have accurate spindle speeds. Small calibration adjustments can be made in the Mach configuration spindle tab, and that is documented below. If your spindle speeds are significantly off, you need to contact MachMotion support for assistance. 

Modbus VFD configuration is described here: Yaskawa V1000 / A1000 / GA500 / GA800 TCP Modbus Communication Setup

is our preferred method to manage a VFD as of 2024 and a modbus system is configured below. 


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