ON topic- turret alignment

Doing a turret alignment- Mori CNC Lathe. The book specifies using an
indicator along the turret tool holder surface. Tapping the Turret until
there is zero indicator movement, in X. Which makes sense obviously. So
long as the tool holder surface is not munged up.
Assuming nothing serious is amiss, seems that indicating a boring tool
holder, or two is on center is the more accurate method, but I am not
one to question Mori.
Previous owner used an interesting trick. Turret face and holder both
use 4 taper pins. They would leave one pin out, and use that one to
re-align. Certainly faster than re-mounting-indicating-mounting again.
But not a secure/strong as 4 pins. In a crash, 3 or 4 is not going to
make much difference. But regular interrupted cutting with 3 vs 4 taper
pins probably does.
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A lot of service engineers I know don`t put the taper pins in.Especially on lathes where the turret has to be pulled to get at the pins. I would think that clocking down the back face of a toolholder seat is for indicating squareness of turret but that you would need to sweep a boring bar holder to get centre.
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Having done many, MANY of these, I can tell you what's always been recommended by Mori factory service, and the slight variations on that which gave the best results for me.
With regard to the pins, most models only came with 2 pins from the factory. The procedure after a crash is to remove the damaged or sheared pins, then put the turret back where it belongs by installing new pins in the holes that were empty (and which, therefore, were not damaged by the crash). Then, with the new pins and fresh holes defining proper position, you ream the holes that were damaged, just enough so they're clean, straight, and will accept new pins. You put new pins in those holes, then REMOVE the pins from the holes that have never been crashed. That way, you always have two holes that were never damaged, and can always realign the turret.
With regard to the right way to check turret alignment, running an indicator along the surface of any clean, undamaged turning tool slot is the way to make sure the turret is in the right place with respect to its rotation. Period. If you then sweep a boring bar holder and find that it's not centered, do NOT try to rotate the turret to fix that.
If one boring holder is above center, there's usually another that's below center; and some will be twisted or angled, or whatever. These are tool holders, not gauges. In some cases, the holders need to be replaced. Sometimes, just the dowel pins on the holders. or the bushings in the turrets that accept these pins, will need to be replaced or repaired. On many machines, a more thorough investigation will show that the spindle is out of line with repect to the turret's proper center height. That's more common that many people realize. Most just align the turret and think the machine is fixed after a crash. Seldom true.
Also, the pins in the turret have nothing to do with the machine's ability to take interrupted cuts. It's the screws holding the coupling halves to the turret and the body casting which are responsible for strength and rigidity. All the pins do is give you a way to put the turret where it belongs, and a way to absorb destructive energy when the screws are overstressed. By the time the pins start to carry even an ounce of cutting (or crashing) load, the machine's already damaged and out of line. So two pins is the way to go, and save two good holes for the future.
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Kirk Gordon

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