Need Help!- Haas VF3 1996 not finding Z-ref.

[Nordic]

Hi all, Im having problem with my (new) old Haas vf3.
For transport the Z motor was taken off and the hydraulic counterb.,electric box.
Cable of the xyz motors were unpluged
I have gone over the pic. of downtake of the machine and pre-pic. of the electrics and all seems to be as it should be.

Now, when I start the machine and set zeroref. and start the machine the Z axis starts to go down to ref.point (I think it is suppose to go down about 2inches) but does not seem to find it and drives Z-axis all the way to the hard stop (ca.100mm) above the table

I did not get any manuals or diagrams with the machine so Im in a "little" bit of a problem.
Has anyone got an idea how to get the electical diagrams and manuals for the machine if I dont know who sold it in the begining?

[Geof]

It sounds like the microswitch for the Z axis home position is faulty.

On Haas machines when the machine homes the Z axis it moves UP slightly until it operates the microswitch, then stops and reverses direction until the switch releases, then it starts counting pulses from the encoder and keeps moving down until the "Z channel signal" is detected. The "Z channel signal" occurs only at a specific point during one rotation of the encoder and this gives the precise zero position for home.

If the microswitch is stuck in the activated position the machine will only go down without counting pulses until it hits the hard stop. If the microswitch does not operate correctly the machine will go up until it hits something hard. You need to find this microswitch and test it.

You can test the switch on the machine by going to the Diagnostics screen and just operating the switch by hand. If it is working you will see an entry in this screen change between 1 and 0. Sorry, I can't recall what the name is for this entry or which page it is on so you will just have to operate the switch while looking at each page and see if anything changes.

Once you have fixed any problem with the switch you may still find the machine does not zero. I mention above how the machine counts encoder pulses between the switch and the Z channel pulse. If this count is too large or too small the machine will stop with a Grid Offset alarm. This may happen if the motor was not replaced in exactly the same alignment to the ball screw. The Grid Offset is adjusted by Parameter 127 and as far as I can remember should be something like 3000 (about 2 or 4 millimeters travel).

[tciofalo]

go to the haas site and you can download the manuel for your control

[aadrew10]

Hey Nordic,

Try this first. Take the way covers off the Z axis so you can get to the ball screw. With the machine off, rotate the ball screw by hand so the spindle raises. Just go about an inch or two. Then turn the machine back on, and try to zero the axis. You may need to use channel locks to get a good grip on the plastic capped end of the ball screw since it's up against the hard stop. Once you get it unstuck, you should be able to turn it by hand.

I had this problem with my X axis a few weeks ago. Sometimes stepper motors can be tricky and remember the last direction they turned. I'm not too clear on the reasoning, but it worked for me, it's an easy try, and might save you a bunch of money.

- Andrew