Emco 6p lathe retrofit/tool turret

[benscale160]

A little update on my tool turret.

While I have not attempted to use the PLC program that I got from centroid yet, I have addressed some of the concerns I had with running the 24vdc turret motor.

As mentioned before, the way the system works is the turret rotates in one direction until the sensors inside indicate the correct tool has been selected, then the turret reverses direction against a pawl locking the tool in place. In this state, the DC motor stalls.

To keep the motor from burning up in the stalled state, I have figured out from taking measurements from my old controller that once the unit locks up, the spike in current is detected, and then reduced using PWM to a safe current that will not burn the motor up.

I'm able to replicate this by using an Arduino micro controller, an h bridge, and a current sensor.

The Arduino controls the turret motor by means of an h bridge. There is also a current sensor monitoring the load on the motor which feeds data back to the micro controller. There is one output relay connected from acorn to the micro controller. When a tool change is called, the relay is energizes thus triggering the micro controller to start searching for the correct tool.

Once the correct tool is found by the four turret sensors, the relay de-energies, the turret reverses and locks.

While the turret it is searching for the correct tool, the micro controller is monitoring current spikes. Why is this important while searching for a tool? Crashes. Been there done that, not much fun. I'm hoping this will help mitigate damage if any should the machine screw up or I have a brain fart.

I also plan to have the microcontroller time out should the turret spin say in excess of two rotations. After this, I figure something is wrong.

As mentioned above, when the correct tool is found, the turret reverses, The motor stalls, the micro controller senses the increase and then reduces it to a safe level with PWM.

I also plan to use the Arduino to reduce the number of inputs required to read the tool position. I'm going to take the four inputs from the gray logic and convert it to binary outputs (0-7) and feed this into the acorn. This will reduce the inputs needed from 4 to 3. Not much, but every input counts here.

More to come

Ben

[martyscncgarage]

A little update on my tool turret.

While I have not attempted to use the PLC program that I got from centroid yet, I have addressed some of the concerns I had with running the 24vdc turret motor.

As mentioned before, the way the system works is the turret rotates in one direction until the sensors inside indicate the correct tool has been selected, then the turret reverses direction against a pawl locking the tool in place. In this state, the DC motor stalls.

To keep the motor from burning up in the stalled state, I have figured out from taking measurements from my old controller that once the unit locks up, the spike in current is detected, and then reduced using PWM to a safe current that will not burn the motor up.

I'm able to replicate this by using an Arduino micro controller, an h bridge, and a current sensor.

The Arduino controls the turret motor by means of an h bridge. There is also a current sensor monitoring the load on the motor which feeds data back to the micro controller. There is one output relay connected from acorn to the micro controller. When a tool change is called, the relay is energizes thus triggering the micro controller to start searching for the correct tool.

Once the correct tool is found by the four turret sensors, the relay de-energies, the turret reverses and locks.

While the turret it is searching for the correct tool, the micro controller is monitoring current spikes. Why is this important while searching for a tool? Crashes. Been there done that, not much fun. I'm hoping this will help mitigate damage if any should the machine screw up or I have a brain fart.

I also plan to have the microcontroller time out should the turret spin say in excess of two rotations. After this, I figure something is wrong.

As mentioned above, when the correct tool is found, the turret reverses, The motor stalls, the micro controller senses the increase and then reduces it to a safe level with PWM.

I also plan to use the Arduino to reduce the number of inputs required to read the tool position. I'm going to take the four inputs from the gray logic and convert it to binary outputs (0-7) and feed this into the acorn. This will reduce the inputs needed from 4 to 3. Not much, but every input counts here.

More to come

Ben

Interesting Ben,
Keep us posted on your progress....I think Jasen reused his turret board on his smaller CNC 5, does the 6P/120 not have a similar arrangement?....
Marty