Dyna 20 won't Z reference home

[3bmachine]

Hello,
I have a 1989 CompuMill bedmill with a Dynapath 20 control. This is a fairly new machine to me - have used is successfully for a short while til just the other day. By mistake, I somehow let the Z go upwards and hit the overtravel switch which threw the machine into E stop. After awhile, I found the reset button in the control cabinet. I pushed that and lowered the Z at the same time and the machine reset itself.

Since then, however, I can't get the machine to Z home. It will physically move upwards til it hits the switch, but the machine does not recognize its home position.......gives me an alarm and says "Z not referenced" I took the front panel off. I lower the z and then try to reference it - I then push the limit switch with my finger and the z travel stops. It should then think its home, correct? But when I let go, it continues to move upward until it hits the switch. I learned that the control only needs two things to recognize z home - the switch being pushed and then finding the nearest marker pulse....so it appears it isn't doing the latter.

I thought the switch might be bad. I went into diagnostics and found the I/0 - it switches between 0 and 1 when I press the switch manually so that says the switch is good, correct? I checked to make sure the switch and the dog were still tight - thought they may have loosened over time and moved - both appear to be tight and in place.

Any thoughts on this?

Thanks in advance!

Shannon

[jagardner4]

A machine tool builder like Compumachine had the ability to alter the way an axis references. Sometimes they would set up the machine to hit the physical limit switch, then reverse the axis and reference coming off the switch. Check the specific sequence used to reference the X and Y axis. That may give you a better idea of what's suppose to happen.

The message you refer to, "Z Axis Not Referenced," will be seen on the Status page as soon as the CNC boots and until you reference the axis. There will also be messages for X and Y as well. These messages will be there until the indicated axis is successfully referenced. You don't want to ask an axis to go to the Home position before it is referenced. Realize that the Home position is not necessarily the same as the Reference position for any axis - the verbiage DynaPath uses is different from other controls.

All that being said, you may have lost the marker channel on the Z axis. Can you swap the Z axis motor with X or Y to check?

[3bmachine]

Got some new information today - when I started on this AM, the x and y would reference home - z would not - just as described on first post.

I then started switching around the drive cards. I did it so many times that I forgot what went where - but with either the x or y card in the Z position, the Z now works.......the dog is down off the switch - it moves upward, hits the switch, and slowly moves back down a slight amount and is referenced. Perfect! That must mean the Z drive is bad - BUT when I put that card back in the X slot, now the x won't reference - it does exactly what the Z did originally - moves towards the switch, contacts the switch, and then stops - does not move back the other way to reference zero. Its almost as if there are now two bad cards - which I'm not buying yet.

So what tells the X to move back off the switch when its referencing?