vk45 fourth axis add?

[Dancy]

I have all the parts to do this. Servo motor, servo drive, cables, resistors, ect.....

anyone know how to enable it on the machine?
anyone know how to configure it?

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[Dancy]

Some things I found....looking at the wiring seems the 4th and the X axis are connected to the same place...a typo? Maybe not. I found something in the Hitachi Maintenance manual that may imply one needs two SVIF boards. Shows a jumper that may select the function of the SVIF. (setting pins = jumpers in Hitachi speak)

Anyone that HAS a fourth axis that could answer silly questions? Was it installed later or did the VK come that way? Do you have two SVIF boards? How are they connected?

[Dancy]

Hoping you might be able to help. I have been wanting to add a fourth axis to my VK45 for years and last year I purchase a second VK45 for parts. I grabbed the X axis servo drive and servo, cables, resistor, relays and the SVIF board. Wired in all parts to my original VK.

I have set the following parameters as follows. I tried to match values to what the X axis has just for testing.
parameter:
5 bit 3 = 1
10 bit 1 = 0
23 = 30
27 = 3
31 = 200
43 = 15000
66 = 500.000
67 = -500.000
71 = 0
75 = 0
79 = -500.000
83 = 0
87 = 0
91 = 0
110 = .0079
137 = 570.000
173 = 10000

I tried all address combinations listed in parameter 01 & 08. Only seems to change the name (A,B,C,U,V & W) on the position display.

Last I did a comparison of the ladder paths for Z and A. It starts at the press of the + button (1084 and 1086) ....triggers coil 3131 & 3133 respectively. The contacts for the latter two then trigger 3261 & 3263 labeled "feed +Z axis, HIY=FO" and "feed +4th axis, HI4=FO". Those coils have no contacts in the ladder and I can't find them in the schematics.

Kept getting the NO OPTION error so I changed param 6 position 6 that matches the address of 4786. Rebooted the machine and boom! No more error! I can now select the A axis with the "Handle" and pressing cw or ccw for A in jog mode no longer creates an alarm.

The position screen now shows X,Y,Z & A. The diagnostic 01 screen now shows all four servos and I was able to adjust the servo "droop" amount to near 0 on the A axis. (AE does not flicker as XE,YE & ZE do). Diagnostic 02, line 3 bits 3&4 toggle when A+ or A- is pressed. Diagnostic 03 line 9 shows *dec of one for X,Y,Z but not A. Line 10 shows all four "ready". Line 11 shows all four "off". Line 13 shows no over travel on any axis. Diagnostic 09, line 60, the A and B phase flicker if I rotate the shaft of the A servo. The multi status "speed", pg 2 will show values for all axis’s except A.

I went through the maintains manual’s servo diagnostics, checking each signal to the servo drive. All were present and of the correct values however when I checked the supply voltage I found the brake relay was not engaged. I had missed a wire. Some interesting things I noticed in this unpowered state. I cannot use 100% rapids (such as when the machine is not had all axis referenced to “zero”). I noticed at times, I can go to the DIAG page and rotate the servo by hand and the encoder count changes. This is not always the case. Seems to happen after a program ends with G28. If the machine state is that I can cause the count to change via rotation, I noticed the VCMD signal would show up the correct polarity for a given direction. If left there more than a few seconds, a 031 WATCHDOG alarm would trigger.

Present state. I fixed the power to the brake relay. Now moving the servo is out of the question. It is being held by the control. It still will not move via “HAND”, “JOG” nor “RAPID” and if in MIDI mode I send G1 F10. A10. I get an immediate 031 WATCHDOG alarm.

I have two Hitachi documents that discuss the watchdog. One involving maintenance of the main board identifies a jumper to disable the watchdog timer (does not seem like a good idea and could cause a servo run away). The second talks about mods to the SVIF board, setting the 8 pos switch and installing a jumper and resistor.

Most I have found says “replace boards”. I don’t think that is the problem as I can disable the 4th axis and no more alarm. Any ideas?