Learn how to check the Turret alignment on a lathe and make turret adjustments on your CNC.

Lathe Turret alignments become necessary for many reasons. Machine crashes are the only reason for needing a turret alignment. The alignment of the turret controls how square your drills will run in your broing bar pockets. The ensure that they run parallel with Z-axis as well as cut on center with the part. If either alignment is out excessive tool wear or breakage will occur as well as sizing problems.. That is why a properly aligned turret is critical to any machining process.

For this turret alignment procedure you will need a magnetic base and an indicator. First, check the squareness of the turret by mounting the indicator in a place where you can sweep across the face of the turret. The indicator should not move when this axis is moved. If it does, you will have to try mounting it on the tailstock, sub spindle or main spindle. In general this should be under .0001 if you are performing the alignment. Depending on tolerance of parts will determine if it is necessary to perform a alignment. If the lathe is doing on center drilling this alignment is much more critical. When a machine is crashed the metal can become distorted so you may want to check multiple stations to confirm you are aligning it to the average tool face. This test checks that the turret face is parallel to the Z-axis slide.

This will affect how true your drills and boring bars run.

Radial or Rotational turret alignment inspection checks

Most CNC lathe turrets have a tool post slot that is milled into them at every station for grooving or turning tools. This slot should be parallel to the axis (usually X) in the cutting position. If there is not any slots, you will need to use a coaxial indicator to sweep the bore. Generally I prefer checking multiple boring bar pockets with a coax and then double check the tool slot. Reason being is the boring bar pocket is farthest from center and will show the most error and is what the true drilling centerline will be once you add your tools. Before mounting a boring bar holder always use a stone to clean up surfaces first and grab the best holder. Use a station number that the metal does not look damaged. If you can not find one then the tool slot is your best bet. Using the coax zero out the indicator with the hand wheel in the X axis plane, then sweep the bore perpendicular to X plane from top to bottom. The top should match the bottom. If it does not, the turret will have to be radially aligned. Double check 2-3 turret pockets just for reference to make sure they are the same and pick the best or average of them. Run the slots for additional reference, they should be zero.

Basic curved coupling Radial Alignment

Contact your machine tool builder or dealer for procedure or have them come in the first time to observe due to many different turret designs and ways to make adjustments. Below is a picture of one side of a basic curved coupling for a turret.