When I got my mill, the wiring was interesting to say the least. There was a single enclosure on the back of the mill, which housed three 3-phase rotary switches, two 3-phase fuse clusters (the same type used by Noah) and a 3-phase outlet, into which the spindle motor is plugged:
Beneath this, a plastic box was precariously hanging by one loose bolt. Opening the box revealed two 3-phase contactors:
A quick note: here in Australia, single phase is 240v and 3-phase is 415v (440 measured between phases). The idea behind using contactors is one of safety. First, the contactors operate by energizing a coil using a momentary action switch. Once the coil is energized, any disruption to the power will result in the contactor opening, thus killing the power to the motor. Therefore, it the power goes out (for any reason) the mill will not jump back into life once the power is restored (unless the start switch is activated). Second, the contactor has a thermal overload, which will kill the power to the motor to prevent damage.
There was however, one major problem here. The two contactors (the x-feed motor and the pump motor) were wired to their respective rotary switches. As these are standard ON/OFF switches, they keep the coil energized, meaning that they offered no protection.
I decided to gut the enclosure and start again. Also, I didn't want to be reaching behind the mill to turn things on, so I decided to make a separate control box. The enclosure was pretty beat up and had several holes that needed blanking plates welded in and a new hinge pin turning up. Not to mention a fair amount of panel beating.
The old fuses were tossed and DIN mounted circuit breakers were used. The control circuitry has its own breaker, as does the spindle motor. The x-feed and pump motors share a breaker and there is a single phase breaker for aux power (light and maybe a DRO in the future). I added an additional contactor, so now each motor is properly protected:
The control box is simple enough and has a start and stop button for each motor. It also has an emergency stop and three neons, to indicate the presence of all three phases of power. On the rear there are the two auxiliary 10A power outlets:
Both were bench tested and the main enclosure was then mounted back into its original position on the rear of the column. I welded up an arm for the control box and mounted it onto the mill:
I assume the mounting point that I attached the arm to is for a DRO. If I get one in the future, it can be mounted on top of the control box.
Beneath this, a plastic box was precariously hanging by one loose bolt. Opening the box revealed two 3-phase contactors:
A quick note: here in Australia, single phase is 240v and 3-phase is 415v (440 measured between phases). The idea behind using contactors is one of safety. First, the contactors operate by energizing a coil using a momentary action switch. Once the coil is energized, any disruption to the power will result in the contactor opening, thus killing the power to the motor. Therefore, it the power goes out (for any reason) the mill will not jump back into life once the power is restored (unless the start switch is activated). Second, the contactor has a thermal overload, which will kill the power to the motor to prevent damage.
There was however, one major problem here. The two contactors (the x-feed motor and the pump motor) were wired to their respective rotary switches. As these are standard ON/OFF switches, they keep the coil energized, meaning that they offered no protection.
I decided to gut the enclosure and start again. Also, I didn't want to be reaching behind the mill to turn things on, so I decided to make a separate control box. The enclosure was pretty beat up and had several holes that needed blanking plates welded in and a new hinge pin turning up. Not to mention a fair amount of panel beating.
The old fuses were tossed and DIN mounted circuit breakers were used. The control circuitry has its own breaker, as does the spindle motor. The x-feed and pump motors share a breaker and there is a single phase breaker for aux power (light and maybe a DRO in the future). I added an additional contactor, so now each motor is properly protected:
The control box is simple enough and has a start and stop button for each motor. It also has an emergency stop and three neons, to indicate the presence of all three phases of power. On the rear there are the two auxiliary 10A power outlets:
Both were bench tested and the main enclosure was then mounted back into its original position on the rear of the column. I welded up an arm for the control box and mounted it onto the mill:
I assume the mounting point that I attached the arm to is for a DRO. If I get one in the future, it can be mounted on top of the control box.
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