Building and installing 4 th axis for Crusader G based machine

[zoeper]

I need to manufacture some nylon cams and need to add a rotary axis to my mill.

Plan: Take a standard 6 or 8" Horizontal/ Vertical rotary table and convert it to CNC by the addition of a servo motor and decoder. I do not see any problems with this conversion and have all the tools at hand to do the mechanics.
The CNC'd rotary table then needs to be interfaced with the controll - and that's where i go (DUH??)

My controll is a Anilam GXM (grusader g) and the servo drives used for the other 3 axis are " DC Servo Amplifier Type 415"

On the controll side i have:
1. A black board accepting inputs from the encoders with U and S still unocupied. (W is used for the readout on the knee of the mill and well X Y and Z is obvious)

2. A Red card with the output sognals for X, Y and Z as well as a ribbon cable marked D/A for controlling coolant on/off, spindle F/R/off etc.

3. A blue card with U, W ans S analog outputs, of which only S is used to controll spindle speed. This card also has a ribbon cable marked EXP and from schematics it seems to be connected to the limit switches and M, S and T strobe inputs.

I can access all the parameters in the controll to set up U as a rotary axis and to set parameters like DIV U, + and - limits for U, rot U etc. and i think that it should be doable to set it up.

Now for the questions....
Do i need to use the same model of servo amp, or would something like a gecho do the trick? (the current amps have the following connections:
= bus
- Bus
+ armature
- Armature
+ 24 V DC
0V
-24 V DC
+ tach
- Tach
Fault
-15 v DC
0v
+15 V dc
enable
- command
+ command
Then there are test points for: Current, Tach, Command and 0V
and also tuning pots for Offset and command gain.

What size servo do i need for a 6 or 8 inch rotary table and would you advise that i gear it down and loose some speed? (i think 90 turns/ rev is standard for that size table)

I suppose i would also have to set up a limit switch on the table for indexing purposes? (and interface that to the controll) I do seem to have a number of D/A and EXP points spare, but how would these be configured in the controll?

I suppose that's enough questions for now.
Thanks
Pieter

[zoeper]

OK, going through circuit diagrams and manuals almost forgotten i stumbled across the Anilam OEM manual for my controll. This gives me all the information i need to hook up the 4 th axis to the controll, and included in there is the pinouts to hook up the axis brake and limit switches.
What i need to do now is to see if i can hook it up with just a motor and encoder and see if i can get it moving under command.

Does anyone know how the limit switch on a rotary axis operates? I would imagine that if you are using the encoder on the motor you would only ned one limit to give a index signal?

The other question that remains is the servo drive and the compatibility of modern units with my system. Any sugestions on this would be much apreciated, as my searches was unable to locate drives similar to the ones used in my system.

Pieter
Anyone wanting to get hold of a copy of the OEM manual feel free to ask.

[drgbt]

I added a 4th axis to a gxm some time back. I ran into trouble with the encoder count. Had to use a 90 to 1 table with a 1000 line encoder to get it work. Even the guys at anilam couldn"t figure out how to change the line count. No need for a limit because the table turning has no limit. On that control you don't have to set it up to home and you can set 0 anywhere you want it.

[zoeper]

I am just looking through the OEM manual and there parameter No. 53 in the installation table is ROTCNT - NUMBER OF LINES ON ENCODER RATARY AXIS: Set at 3600. Consult Anilam before making any change.
I can not see how any math involving 360 deg, 360/90 or 1000 counts is going to give you the 3600 that Anilam stipulates
I wonder why they would list it as a parameter if it is set in stone??

Am i right in asuming that you only used the controll signal and the encoder feedback to the controll to wire it up then?

What is the size of your rotary table, and what size motor did you use, or would you use if you did it again?

Pieter

[drgbt]

Thats the one I had trouble with. Rick at Anilam couldn't even figure out how to change it and he designed the contol. I would enter the pass word. It would allow me to change the number and I would save it and reboot but it had no affect.

[zoeper]

DRGBT,

So by putting a 1000 count encoder on the motor and using a 90 turn = 360 deg rotary table solved the problem even with the parameter as it is?

Do you have any pictures of your ratary axis?
Pieter

[drgbt]

Sounds right. Its been over a year and I sold the machine so I can't verify. I have a suspicion a change in the software was required to change the line count.

[zoeper]

I bought a nema23 brushless servo (with 1000 line encoder) and amp on e-bay, but looking at the specs i fear it could be on the light side. 6.6Lbs/in cont stall torque. dialing this into my torque driver and turning the handwheel on the rotary table (90:1) a fly might be able to stop it. dialing 4x that torqe into the driver starts to feel like business and it should be a breeze reducing speed by 4:1 (motor rated at 6000 rpm (gives 16rpm at the table)
My only concern is with what drgbt said about the controller being fussy about anything other than 90:1 and 1000 line encoder.

Do these brushless motors use the encoder output for phasing or could i in theory mount the encoder on the handwheel and have reduction between the motor and the handwheel stud?

If that's the case i would be happy to live with 4-8 rpm and rather have torque to spare.

[drgbt]

Any way you put the encoder on the input shaft of the rotary table instead of on the motor?

[zoeper]

DRGBT, i'm not sure what youre asking. If you're asking how the encoder is going to be mounted on the input shaft of the rotary table, i have not worked out all that detail yet, but i dont see any major problems doing that.

My bigger concern is that the motor drive might need input from the encoder to work out the phasing of the motor, in which case i might confuse the drive completely by putting the encoder somewhere other than on the motor.

I also worked out that using a 1:6 reduction from the motor to input shaft of the rotary table should give me (a very decent) 3564 lb-in (or 400 Nm) of torque at the working end @ 11.1RPM (That's 5.4s / revolution)

[zoeper]

My drive arrived on Friday and the motor should make it here by Wednesday or Thursday.
I can't wait for the hookup and testing to see if it will run on my machine.
Expect some feedback soon.
The drive is a parker compumotor TQ10 brushless ac drive and i was quite impressed to see that it can also be used to drive brushed DC motors. Is this a standard feature of AC servo drives? If so I would like to get hold of 3 more to replace the existing DC drives in my machine. (they would have to be a bit bigger than the one i just got though)
P