1995 VF-OE Spindle dropping out mid program

Hi folks,

Sorry about the barrage of questions lately but after 6 months of waiting delays and problems I finally have a machine that mostly works as it should, and now I'm tackling the snags.

So, sometimes 40 minutes, sometimes 5, and occasionally immediately but either way the spindle will stop mid program.

The control thinks its still running on the diagnostic page. 1 displayed at the SP CW line.
The relay board LED is out however, relay not in the on position (visible through the clear plastic case)
And the table will happily keep on going and would break a tool if I didn't catch it in time.

I can accelerate the spindle dropping out by overriding the feedrate +20 or 30%, and that's cutting fresh air on a part 70% cut but never finished because of the spindle! I've even turned the spindle down whilst cutting the fresh air.

Logically it seems the signal is getting lost from the "brain" to the relay board. Could it be a voltage dropping somewhere? Poor power supply?

I'm programming it at 3.5m/min out of a possible 5m/min maximum (200inches) and it does tend to kick out at rapid moves which leads me to the voltage drop issue again.

Any hints or suggestions most welcome - I have nearly machined a complete part after owning this reliability disaster for 10months!!

Thanks,
Tom.

You could check to see if the 0-10v spindle signal is reaching the spindle drive, at least I assume this uses a spindle drive and not a vector drive. I just recently had an issue I tracked down to the connector coming off the maincon. It took reseating and some dielectric to fix. If the spindle return signal matches the in, I'd guess the drive is faulty. There are some diagnostics on it I think, some numbers that flash or something.

Thanks for that.

As I suspected, I'll have to spend some patient time going over the connectors very slowly.

Is there a confirmation signal that the spindle is turning that can be seen in the diagnostic page?

I can't recall for sure, but I think there is a commanded speed and real speed. If I recall correctly, the drive returns a real speed with a 0-10v signal.

Thanks for your help.

Went around with a can of switch cleaner and disconnected, cleaned, worked, and reconnected just about every connection in the cabinet.
Satisfying job to do but sadly still hasn't cured the problem.

I'm guessing now that it must be one of the ribbon cables but I'll have to try and chase things and work logically up the line.
At least I'm managing to use the machine albeit slowly, which is 10 times better than it being a 4ton paperweight!

Have you checked the command voltage at the drive at commanded speed? It should be linear, 10v = max rpm

Not as yet. A commanded max of 7500 delivers an apparent 7623rpm actual rpm on the current commands page.

Spindle seems to kicks out on jerky rapid moves but as previously overriding the feedrate to 60% allows me to complete a long program.

I'd really sort of suspect the drive. The drive also supplies your high voltage dc, at least if it is brushless. Perhaps the internal caps, or diode bridge?

This is a brushed servo machine, last of the line apaprently.

12v and 5v DC supply comes from a metal box up the top that I suspect is just like what you might find in a PC judging by the plugs and wire colours.

Ok, news is that it's getting the signal perfectly. 10v at 7500, 5v at 3750rpm.

Soon as it misbehaves again I'll see if it's still being told what RPM to run at.