Lathe tailstock alignment on CNC machinery and equipment

Tailstock alignments on CNC lathes are usually very simple. But do require that the main spindle or headstock be in perfect alignment first. Some people will use a coax indicator and clamp it in the main spindle and then sweep the center of the tailstock. This setup is only good to get it close and is not usually necessary. The correct way to align the tailstock is to chuck a piece of bar stock in the spindle at least 3" in diameter if possible and a minimum of a foot long. The diameter should be large enough that it does not deflect during cutting.

Check alignment of lathe tailstock to spindle

1. Perform head stock alignment first!! (Under .0004" taper over 6 inches approx.)
2. Chuck up a minimum 3" material to prevent deflection from tool pressure. Use a test piece long enough to simulate your actual part
3. You may want to consider checking the machine level before making the adjustment. Especially if it is a long bed machine.
4. Engage tailstock
5. Make short program to turn and entire length of part
6. Measure diameter at each end and subtract the large end from the small end to determine how much taper is present
7. Also check in middle of the part to verify there was no deflection when the part was machined.

Once you find out how much taper you have. You will need to find some adjustment push pull screws to move the tailstock up and down. There will also be hold down bolts similar to a headstock or turret body. There is also a gib that can be adjusted if necessary.

Tailstock alignment and machine adjustment

There are several ways to align a tailstock which works simliar for any CNC or basic machine. The way below describes adjusting the tailstock when engaged with the part. This removes any backlash from the gib for the tailstock and ensures the tailstock should be parallel to the axis.

1. First lock the push-pull screws against each other to prevent movement when cracking the main hold down bolts.
2. Crack loose the hold down bolts for the tailstock body
3. Engage the tailstock
4. Adjust the push pull screws slightly
5. Snug up the tailstock body bolts
6. Take another cut and check taper. You may be off more then when you started the first time. This is normal.
7. Repeat this procedure and make multiple adjustments until the taper is eliminated
8. Tighten down the hold down bolts
9. Take another cut to make sure nothing moved after locking down bolts