CNC Lathe spindle motor – part 2 [Configuration in Mach 4]

In this blog we will introduce, how we setup parameters on VFD and configure in Mach 4. In blog before – CNC Lathe spindle motor – part 1 [setup&wiring] we presented mechanical and electrical part of project how to CNC Lathe spindle motor setup and wiring electromotor and VFD. If you had problems with configuration in Mach 4 in description you will find out all information for proper setting.

VFD parameters configuring

Variable frequency drive (VFD) drives an electric motor by changing – varying the frequency and voltage supplied to the electric motor. For operation we want functions: ON/OFF motor, control speed and direction CW – CCW. All these functions can be controlled via PoKeys57CNC.

For Lathe spindle and our needs we decide to have around 2000 Rpm. So 2000 rpm is starting point to calculate the rpm and frequency and than setup on VFD. So in calculation with frequency we decide the max frequency for electric motor is 70 Hz, 70 Hz for permanetly working is upper limit and 30 Hz for lower limit- for permanetly working. The max. Rpm (1918 rpm) is fine we have a deviation but we use the manufacturer directions (electric motor) for permantly working frequency (Hz). Calculated rpm and frequency we used to set an VFD and configure in Mach 4.

limit spindle speed
Pulley ratio - CNC Lathe spindle motor

VFD function parameters setting

So we calculate the Rpm. Rpm working area is enough for our needs and efficiencies of our CNC Lathe machine. VFD setting parameters. For correctly working we must set three parameters on VFD-INVT GD20-0R7G-2S-EU. Correctly wiring and setting parameters is important for properly and easier Configuration in Mach 4.

 VFD function parameters setting

Configuration in Mach 4

Starting with setting Output Signal, to set ON/OFF electric motor and direction CW/ CCW.

Output signals - ON/OFF, CW/CCW

Control Configuration

PoKeys plugin configuration. Setting Pin17 (0-10V) for control speed (varying the voltage).Varying the voltage on cnc controller- Varying frequency on VFD and Varying speed- rpm on spindle.

PWM output -CNC Lathe spindle speed control
CNC Lathe Spindle RPM setting

CNC Lathe Spindle synchronisation

So, we set the machine in operation, settings are fine to start turning and drilling. If we want to make thread cutting on machine we must synchronisation spindle. CNC Lathe thread cutting requires Spindle speed synchronisation, which means spindle RPM-s must be synchonisation with machine linear movement.

To archive this, CNC controller needs to read feedback signal from Lathe spindle to gain information at which RPM-s spindle rotates.

For this purpose we used Optocoupler, Optocoupler – Index is sort of sensor that would read spindle RPM-s.

On upper photo we can see RPM-s (1931rpm)- we talk about (1918 rpm), and set the VFD frequency. So We have small deviation between calculated value and real value on machine. Can be more faults:

Pulleys are not in correct ratio – pulley dimension – dimensional deviation.

VFD frequency varying.

Wiring diagram – Index – Pokeys57CNC

In photo below – is wiring diagram for connection Optocoupler with Pokeys57CNC via Adapter Board 10 -10.

wiring diagram- Index - CNC Lathe - PoKeys57CNC

CNC lathe spindle Index – settings

Index -CNC Lathe  spindle speed measurements
Encoders- enable fast encoder
CNC Lathe Spindle Rpm- setting

CNC Lathe turning – test part

The this photo below – cnc turning an test part. Turning was fine and machine work properly.

test part - CNC Lathe

More about

PoLabs web page

For more information about step by step quide PoKeys57CNC and Mach 4

More information about Pokeys I/O devices

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