Haas VF2 Z axis crash, now Z is off .027"

[SC300DRIFTER]

I recently had a .250 pin stop to locate a part in a production program and someone removed the M0 that stopped the pin just above the part to locate it. The pin came down and slammed into the part alarming the machine out. Z axis still moved and I was able to handle jog it up and return it to home position, the ATC still operates smooth and everything seems fine EXCEPT Z axis is off .027"

The problem is Z axis seems to be off now. I used an indicator and a Renishaw probe to pick up a known position (table) and it repeatedly came out .027" with both methods.

Any suggestions or recommendations on how to correct this difference in Z axis would be greatly appreciated. We have about 80 programs on this machine that all have preset offsets in the programs, they will all need to be adjusted accordingly if we cant correct the .027" in Z axis globally. Is there a way to adjust this in the parameters?

Thanks! This is my first post here at CNCZone so I am not sure if I put this in the correct spot.

[mniadna]

I crashed Z once and it backed the locking nut off the support bearing(servo side) It made my Z off. You could hear the ball screw slap back and forth when you would rapid Z from + to -.

[Delw]

does it repeat everytime except its .027 off?
recalibrate your probe.

then do all your tools on the tool setter

[Geof]

As far as I recall the connection between the servo motor and the ballscrew is not fixed with a keyway but is a friction grip which can slip if severely overload. I suspect this is what happened in your case, the pitch on the Z axis screw is about 0.2" I think so your 0.027" represents about 40 degrees of slip.

I think the only way to get back to your original position would be to release and retighten this clamp with everything in the original position but this would be difficult. You might be able to do it by resting the nose of the spindle on something solid and recording the Z axis position. Then release the clamp and jog the motor by 0.027" before retightening it. But this approach is a bit hokey and I doubt whether it could be done to a good enough accuracy.

It also means working on the machine with everything powered up and active which is not a good idea.

There is no way I know about to change the 0.027" in the Parameters. The homing position is determined by the position of the position marker signal from the encoder. This is a signal that occurs at a precise position of the encoder which corresponds to a precise position of the screw, your crash has moved the relationship between the two.

[mniadna]

I think you could use "grid shift" to correct for the .027" I think that would alter your too changer height, though...

[behindpropeller]

I recently had a .250 pin stop to locate a part in a production program and someone removed the M0 that stopped the pin just above the part to locate it. The pin came down and slammed into the part alarming the machine out. Z axis still moved and I was able to handle jog it up and return it to home position, the ATC still operates smooth and everything seems fine EXCEPT Z axis is off .027"

The problem is Z axis seems to be off now. I used an indicator and a Renishaw probe to pick up a known position (table) and it repeatedly came out .027" with both methods.

Any suggestions or recommendations on how to correct this difference in Z axis would be greatly appreciated. We have about 80 programs on this machine that all have preset offsets in the programs, they will all need to be adjusted accordingly if we cant correct the .027" in Z axis globally. Is there a way to adjust this in the parameters?

Thanks! This is my first post here at CNCZone so I am not sure if I put this in the correct spot.

Did you re-zero the machine after the crash?

If it was off by that much wouldn't it make the tool change position off too?

[Geof]

.....If it was off by that much wouldn't it make the tool change position off too?

It will be off but 0.027" is not enough off to cause problems with the tool changer. I had a machine that was off by about 0.1" and it still changed, it was noisy but it changed.

[smallplanes]

Does thee Haas have a soft overload and a hard overload? Our our 6 Mori does so we have never had that kind of problem. I want to learn all i can about the Haas because we should be getting a VF-9 coming in any day now. We are just going to be running light weight parts on it but long. I hope you get it fixed so i will know how to fix it myself. Thanks and the best of luck to you.



Thanks and good luck
Ivan

[Geof]

What do you mean by soft overload and hard overload?

[Machineit]

What do you mean by soft overload and hard overload?

Maybe "Soft Limit" and Hard Limit." Soft meaning the switch and hard meaning a physical limit.

[smallplanes]

Yes those are the switches i,m talking about and they should save your machine from damage.

Thanks

[underthetire]

Err, let me correct the Mori thing. ALL Mori's will or can move the Z axis in a crash. The hard/soft limits have nothing at all to do with a Spindle in to a part. I would suspect your tool change is now off .027 as well. Would you really notice it? Probably not on the umbrella changer, but you might on a side mount. I would do an axis shift to move the Z down by the .027 before I did any re-calibration. Excess wear on tool changer parts is common on all mills from Z crashes moving the servo coupling. I would check the coupling bolts to make sure the collet is still tight, sometimes spinning them like you did can loosen things up, last thing you want is a head coming loose and sinking in to the table. Seen it, dont like it. Haas should have a parameter similar to grid shift on a Fanuc, although i'm really just cutting my teeth configuring a Haas right now. There are a whole lot of options in parameters for those, and they are spelled out much nicer than the fanuc stuff.