How to Align Lathe Tailstock

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Aligning the tailstock of your lathe with the headstock is an essential adjustment that every lathe operator should know how to make. Learn about lathe tailstock alignment, why alignment is necessary, and how to align lathe tailstock for your required level of precision. 

How to Align Lathe Tailstock

The tailstock of a lathe is located on the right side. Unlike the headstock, which is fixed in place, the tailstock can slide back and forth on rails attached to the lathe’s bed or carriage

Lathe machine

Tailstocks are generally made in two pieces – an upper and lower piece. The lower piece is fixed in place, but the upper piece can be moved either forward or back. 

Sometimes, the upper piece moves out of alignment. This could be due to excessive vibration or heavy use. Another reason the upper piece might be misaligned is called the off-center taper technique. In this method of creating tapers, the tailstock is adjusted to be significantly out of alignment. 

If you notice that you’re unintentionally tapering every workpiece, that’s a good indicator that your tailstock is significantly out of alignment and needs adjustment. Budget friendly lathes will need aligning more frequently, but even lathes designed for specific activities like bowl turning will need aligning occasionally.

Roughly Align a Lathe Tailstock By Sight

If your work doesn’t require accuracy to the nearest thousandth of an inch, you can align your tailstock by sight instead of using a test bar. 

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  1. Loosen the tailstock clamp. The tailstock clamp is what connects it to the bed. You will not be able to adjust the tailstock if this clamp is tightened. 
  2. Insert tools into the set screws. The tailstock has two set screws, one on either side. They are usually turned using a screwdriver, socket wrench, or Allen key. 
  3. Find the index markers. There should be a line or arrow on the upper pieces of the tailstock, and a matching line or arrow on the lower piece. Find these index markers to tell roughly how far out of alignment the tailstock is. 
  4. Align the pieces. Turn the set screws against each other and watch the index markers. Adjust the tailstock from side to side until the index markers are aligned. This ‘by sight’ method is a good benchmark 
  5. Tighten the tailstock clamp. Reattach the tailstock to the bed using the clamp. 

Perfectly Align a Lathe Tailstock With a Test Bar and Indicator Dial

If you’re doing precision work, use a test bar and indicator dial to perfectly align your tailstock with your headstock. Test bars are perfectly straight and perfectly round rods with center holes on each end. 

Lathe machine tail lock
  1. Clean out the headstock and tailstock. Remove all attachments from the headstock and tailstock. Clean out the headstock bore and the tailstock quill. Using a rag and your fingers, ensure there are no metal chips or waste material remaining.
  2. Install good centers. To use a test bar for aligning a lathe, you must have an undamaged and accurate center installed in both the headstock and the tailstock. You may wish to use a brand new center for this purpose. Suspend the test bar between the headstock and the tailstock. 
  3. Place a dial indicator in the tool rest. The dial indicator should be perpendicular to the test bar with the plunger tip resting roughly at the center of the test bar. 
  4. Adjust the tool rest. Move the tool rest as far to the left of the carriage as it will go. Bring the tool rest closer to the test bar, depressing the plunger, until the dial reads zero. 
  5. Check the alignment. Slide the tool rest down the carriage rails towards the tailstock, watching the indicator. If the headstock and tailstock are in alignment, the dial will read zero for the entire time. If the dial moves, this indicates a misalignment. Park the tool rest at the area of greatest discrepancy. 
  6. Align the tailstock with the headstock. Unlock the tailstock, freeing it from the lathe bed. Keeping the dial in place, use screwdrivers, socket wrenches, or an Allen key to move the top of the tailstock towards or away from you until the dial reads zero. Lock the tailstock down again. 
  7. Recheck the alignment. Slide the indicator back and forth along the test bar again, watching the dial. Adjust the tailstock again if necessary. When the dial reads zero across the whole length of the test bar, your headstock and tailstock are aligned. 

Conclusion

Aligning the tailstock of a lathe is sometimes necessary to correct a taper. Using a test bar and indicator dial, you can precisely align your tailstock to the nearest thousandth of an inch. For less precise application, you can align the tailstock by sight, using just the index markers on the top and bottom pieces of the tailstock. 

Ellenkate grew up on job sites run by her family’s construction company. She earned her theater degree from The Hartt School, a prestigious performing arts conservatory in Connecticut. Her design and DIY work from her Chicago loft was featured in the Chicago Reader and on Apartment Therapy.