Lathe center crash, centerline is off

We had a bad crash on a Mazak quick turn nexus 100 ms. Tools were about .150" above centerline because the turret was knocked out of position.
We had mazak out for repairs and he reset the turret rotation so it runs true with the X axis. The machine still leaves a .016-.020" nub when facing. when I went to dial the drill holder in it was out about .040" total runout the highpoint being what would be Y axis. How do we bring the machine back on center if we can't operate the Y axis?

.. you doo the job right the next time- that's how.


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Think Snow Eh!
Ox

.020 nub and .040 runout... Your .020" off.

I hope you didn't pay the guy.

Did you watch him realign it? Did he just pop the taper
pins in and call it good?

Did he realign the headstock first? When you have a crash, you have
to square up the spindle first.. Especially on a slant bed.

Odds are that if you knocked the turret out, you knocked the spindle
out too.

Squaring up a 2 axis lathe is really something you should learn how to do, no
need to call a tech.. And WAIT.. And then PAY.. Just knock her back into
square and keep making chips.

so first. Check you spindle, make sure that you are not cutting a taper.

And then you have to knock the turret back in.

And then we can all have the taper pin argument AGAIN...

Something a lot of techs overlook after a crash is to make sure the face of the turret is parallel to the X axis travel. Checking the headstock should align the spindle to the X and Z axis. If the turret face is not square, the turret must be aligned to the X slide before aligning the turret rotation to get the tools on center.

Thanks for advice.

So the tech aligned the rotation of the turret to the x axis, didn't look at the spindle

Bobw said:

Squaring up a 2 axis lathe is really something you should learn how to do, no
need to call a tech.. And WAIT.. And then PAY.. Just knock her back into
square and keep making chips.

so first. Check you spindle, make sure that you are not cutting a taper.

Click to expand...

Care to elaborate a bit on the process of truing/squaring a 2 axis lathe? I might need this in the future lol

metalmadness said:

Care to elaborate a bit on the process of truing/squaring a 2 axis lathe? I might need this in the future lol

Click to expand...

So long as the headstock is on the same plane as the rest of the bed this is what I do.

-Align the face of the turret along the x axis of the machines travel.
-Align the rotation of the turret to the spindle centerline,
-Take a very light test cut and measure the taper. If there is significant taper, loosen the headstock, rotate it, tighten it down, and take another test cut. Keep doing this until you have little to no taper. You can get the alignment very close with this method but not perfect, in theory the test part should measure slightly bigger farther from the spindle due to deflection.

TheBigLebowski said:

So long as the headstock is on the same plane as the rest of the bed this is what I do.

-Align the face of the turret along the x axis of the machines travel.
-Align the rotation of the turret to the spindle centerline,
-Take a very light test cut and measure the taper. If there is significant taper, loosen the headstock, rotate it, tighten it down, and take another test cut. Keep doing this until you have little to no taper. You can get the alignment very close with this method but not perfect, in theory the test part should measure slightly bigger farther from the spindle due to deflection.

Click to expand...

If the headstock weren't in the same plane, you would just need to re-align the turret rotation once more IF the headstock needed to be rotated correct?

70olds said:

If the headstock weren't in the same plane, you would just need to re-align the turret rotation once more IF the headstock needed to be rotated correct?

Click to expand...

Something like that. Unless you are out by a mile, I'd just do the headstock before the turret.

You're generally going to take your test cuts on something thats a bit beefy, so .20 or .030
above or below centerline isn't going to kill you.

It really is a lot easier to get it all dialed in when the headstock and the turret are both
on the same plane.

We had a lathe like that where I used to work. X axis slide was horizontal. a '96
Mazak QT20. Every time somebody crashed it. Just loosed the 8 bolts, push the taper
pins in, tighten, pull the pins, and it was always nuts. Then do the head stock..

On a slant bed, if your headstock isn't lined up EXACTLY like it was at the factory,
your taper pins probably aren't going to get you close enough. Depending where the
pivot is for the headstock, a tenth this way or that way over 6 inches can land you
either WAY over here.. Or WAY over there.