Table of Contents
Spindle motor before conversion
With the asset- CNC lathe (Prvomajska Tabturn 100), on the machine was installed an electric motor – 1 phase with power 250W and spindle RPM (4500 rpm/min) was extremely high for such type of machine. The electric motor had function ON/ OFF and change the direction of rotation spindle CW/CCW.
3d Idea for CNC Lathe spindle motor
We decide to replace the electric motor. Upper data (4500 Rpm/min) were the base for choice. The spindle on our CNC lathe is not made for such high RPM. So we decide to set up a 3- phase asynchronous electric motor and VFD. The previous motor was 1- phase 250W. We selected 3 – phase electric motor,power: 550W,2-pole – 2740 RPM/min.
For the choice of the correct type of motor, we had two conditions: limitation with workplace and high power and torque. When the motor was chosen, was next step to correct reducing RPM with a pulley to make the correct ratio. The ratio in our case is 2:1, that’s means the pulley on an electric motor is 75mm and the pulley on the spindle is 150mm. Gear ratio 2:1 in our case means 1370 rpm/min on the spindle at line frequency 50 Hz. VFD makes it possible for us we can manage to reach higher or lower rpm.
Setup new components on CNC lathe – Lathe setup
Below are the main components that we use it for the new CNC Lathe spindle motor setup. From the 3d model – we can see, that there we were also reduced with a place at an assembly. Assembly starts with the fastening of the holder of an electric motor. The holder has alignment holes which assist for an easier assembly and correct belt tension when the motor is fixed on the holder and the belt is on the pulley then we insure for correct belt tension.
3-phase asynchronous motor
Asynchronous motor: 2 pole – 2740 rpm/min – 50 Hz, power rating 0,55 kW.
VFD-Variable frequency driver
AC 1 phase 220 V input, AC 3 phase output, power rating 0,75 kW
Inverter Input filter
Inverter input filter. AC 1PH 220V, 50/60 Hz. The inverter input filter is recommended, inverter input filter reduce ripple effects
Wiring a new components
The below photo-wiring diagram presents connecting variable frequency drive to the electromotor. L/N and ground wires are connected to wire terminal blocks which are mounted in the CNC control box. In the wiring diagram, we can see the input filter, variable frequency drive, and 3- phase electric motor.
The diagram below – is the control wiring diagram. Control wiring diagrams include Variable frequency drive, Pokeys 57 CNC, and Relay.
Additional information for CNC Lathe spindle motor
Under download find Pokeys 57CNC user manual.
Finally, here you can check also the configuration for CNC lathe in Mach4.
Here is a complete explanation about the stepper motor driver.
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