Forest-line Gantry Mill Control Issues

Good Morning,
I have a forest-line gantry mill that i currently have control issues with.
This machine is a series 11 fanuc control.
We had a power failure in our plant 6 months ago and ever since then we have been having issues with the machine.
We had the main spindle motor drive go bad (old analog siemens unit) we replaced it with a bardax digital dc drive.
Everything on the machine works fine with the new drive except the m19 indexing operation.
Ive had fanuc in here, i've had fives in here (they own forest-line now) and no one seems to know how this machine indexes.
M19 does not call up any parameters etc.
This machine is a 1992 vintage and its almost impossible to go through the ladder.
i am wits end with trying to figure it out.
Currently we are running it in "manual mode" only so much lines of G-code at a time.
any help or advice would be greatly appreciated.

This is going to be tough due to the original "bastardized" configuration using the Siemens drive. If the drive had been Fanuc then the M19 interface is pretty well documented. These hybrid setups are developed by the machine builder and lots of understanding of what they did 25+ years ago is lost.

Orientation is performed in two different methods. Electrically, and mechanically. An electric system uses the spindle motor to rotate until a magnetic flux sensor is activated and the drive holds the motor at the point that the magnetic flux signals are balanced. Mechanical orientation usually involves a lock pin or roller engaging a detent or hole in the spindle shaft with some prox sensors to verify location and state of engagement or release.

Typically in a hybrid setup with a drive that has orientation capability, when M19 is commanded, the ladder logic will output a Y address (physical output determined by the machine builder). If the logic conditions are met and place the CNC program and Ladder program in a "hold" state. When the spindle drive sees the Y signal as an input, it begins it's orientation function. Once the spindle drive has completed the orientation, it outputs a signal to the ladder that is read as an X input (physical input determined by the machine builder) to release the "hold" condition and allow the CNC program or Ladder program to resume execution.

Since all of this is determined by the machine builder, it will be very difficult to try to figure out over the web. An experienced tech on-site should be able to figure this out. It's not likely to be quick and easy though. The first place to start would be to determine if your machine uses an electric or mechanical orientation and if it is electric, does your new drive have an electric orientation function.

i believe it might be "mechanical" through an encoder pulse. There are no signals going to the drive to tell it to orient or anything like that during the m19 cycle. The control tell me like -50000 in the c axis, and that is it. I'm with you that this is a very strange and going to be very hard to figure out over the web but i appreciate all the input.

INDmachine said:

i believe it might be "mechanical" through an encoder pulse. There are no signals going to the drive to tell it to orient or anything like that during the m19 cycle. The control tell me like -50000 in the c axis, and that is it. I'm with you that this is a very strange and going to be very hard to figure out over the web but i appreciate all the input.

Click to expand...

That could be possible. Using the spindle as a "C axis" for orientation is possible AFAIK if the drive was Fanuc, but I've never seen it done that way. Using a 3rd party drive can only add to the mystery.

All I can do is wish you luck!

INDmachine said:

i believe it might be "mechanical" through an encoder pulse. There are no signals going to the drive to tell it to orient or anything like that during the m19 cycle. The control tell me like -50000 in the c axis, and that is it. I'm with you that this is a very strange and going to be very hard to figure out over the web but i appreciate all the input.

Click to expand...

To have any hope of solving this, you are first going to have to find out if this machine uses a hall effect sensor which in effect is a switch for determining home position or if it is using an encoder to determine position.

If it is a hall effect switch, then you need to find out if it is working. i.e. changes state at home position.

If it is an encoder then the control will need to be seeing pulses going in to the C-Axis. Make sure the belt is not broken to the encoder if it has an encoder.

Due to the age and that everything seems to work except the M19, I'm willing to bet that it has the hall effect sensor. If you actually had an encoder on the C-axis, there would probably be position errors showing up.

You also did not say exactly what it is doing during an M19. Normally on a machine with a hall effect sensor or the shot pin approach, the spindle will rotate slowly until home position is reached. The spindle will lock into position either by a brake, shot pin, or electrical hold.

If the spindle is just doing a slow rotate without stopping, then it is a sensor issue. If it is just setting there, then you have a much bigger hill to climb.

To answer your question about rotating etc. IT will just sit there.... if i manually move/spin the spindle by hand, lets say 20 degrees it will return to where it was. seems to be holding location via electrically, but there are no signals going to the drive to tell it to do something.

INDmachine said:

To answer your question about rotating etc. IT will just sit there.... if i manually move/spin the spindle by hand, lets say 20 degrees it will return to where it was. seems to be holding location via electrically, but there are no signals going to the drive to tell it to do something.

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Okay. It sounds like this system is close to working.

Does the spindle return to the home position from both directions? Why I ask is that an encoder system will return the spindle from either direction. A hall effect sensor will usually only return from a single direction.

It sounds like the control is not seeing the home position signal for the C axis.

Do you have schematics for this machine? If you do it should be relatively easy to figure out what is not happening.

I can certainly be wrong, but none of my Fanuc stuff uses Hall Effect sensors. They use VR sensors and a polarized magnet.

Probably not helpful to the problem here, but just wanted to say that "indexing" something via a hall effect sensor is a real difficult, typically impossible task.

You need a sensor with a variable output, not just on/off. On/off doesn't tell you enough.

Garwood said:

I can certainly be wrong, but none of my Fanuc stuff uses Hall Effect sensors. They use VR sensors and a polarized magnet.

Probably not helpful to the problem here, but just wanted to say that "indexing" something via a hall effect sensor is a real difficult, typically impossible task.

You need a sensor with a variable output, not just on/off. On/off doesn't tell you enough.

Click to expand...

I've worked on some machines that did use a Hall effect sensor on a Fanuc control. An OM to be specific.

The sensor was used to only determine if the spindle was in the home-orient position so on/off was adequate. It also used a pulse coder for the other needed information.

This is why I'm asking about if it returns to home from both sides or just one.

A true position encoder will correct error from both directions, the Hall Effect sensor only from one.

yes i can ture it CCW or CW and it will go back to the same point, right now i'm leaning towards the encoder either not giving the pulse, or the control not seeing it. i will keep everyone posted.