Centroid Community CNC Support Forum

I have a working Ajax converted 3 axis cnc mill that I added a DC1 for a 4th axis. I wired it all up with the exception of the servo power to the 4th axis. I went to the PID menu and all 4 encoders read rotation the way they should on that menu and I changed parameter 94 and 131 to indicate the rotary axis. Now if I attempt to home the machine or move any axis I get rapid movement and a stall error on an axis I didn't attempt to move. I then unhooked all connections associated with the 4th axis and restarted the system and get a continuing communication error with the 4th axis. I would like to do some work with the machine tomorrow but I am a bit lost. I am not sure if I should start from scratch on the machine setup or ? Any help is appreciated.

Brad,

It sounds like your encoder may be wired incorrectly causing it to count backwards.

While looking at the faceplate of the motor and with the shaft of the motor pointing towards you, rotate the motor shaft CCW and the count in the PID screen should get more positive.
If you rotate the motor shaft CW, it should get more negative

The 4th axis encoder does count up with ccw rotation. On the pid screen each encoder reads on the axis it should when that servo is rotated. When I use the jog panel and press Z- I get Y- movement, Z+= Y+ movement, Y-=X+ movement, Y+= X- movement, X+= 4th axis cw rotation, X-= 4th axis ccw rotation, pressing either 4th axis button on the jog panel gives a stall error.

Brad,

You need to change the drive mapping parameters (300-307). When you connected the DC1, the DC1 became Drive 1, so the parameters need to be changed accordingly. (300 = 2, 301 = 3, 302 = 4, 303 = 1)

That solved that problem. Next issue is homing the 4th axis. I installed a single switch that gets triggered on one point of the indexer. If I press Alt-I and cycle the switch I dont get a changing light like I do with the other limits so I can tell it where to home to. What do I have to do to fix this issue? Thanks for the help, I would pull my hair out trying to figure this out all on my own.

I used the search feature like I should have in the first place and figured out what to do with the homing switch and how to change my .hom file so I can home the machine. I have been trying to figure out what values to input on the jog and motor screens. Everything is set up for inches of travel per revolution and not degrees for the 4th axis. My dividing head is a 40 to 1 ratio, my servo to dividing head ratio is 2 to 1 so it takes 80 servo revolutions to turn the 4th axis 1 revolution. The encoder is 1000 line.

when you define an axis in the CNC11 setup parameters as a rotary axis (not linear) the turns ratio units in the setup table want REV/Degree revolution of the servo motor per degree of movement
so in other words.. how many revs of the servo motor will produce 1 degree of movement on the rotary table.

also be sure to adjust the Fast, Slow and Rapid rates for the rotary axis.. as they will now be in degrees per minute.. so typical values are
Slow jog = 2000 degrees per minute
Fast Jog 4000 Rapid 9000

i attached a rotary table install manual as a general guide