The tailstock is one of the basic components of a conventional lathe. It is situated on the opposite side to the headstock and can be moved along the machine bed. Its main function is to support the workpiece in the lathe, particularly when the workpiece is long, slender or prone to bending.
The tailstock is one of the basic components of a conventional lathe. It is situated on the opposite side to the headstock and can be moved along the machine bed. Its main purpose is to support the workpiece in the lathe, particularly when the workpiece is long, slender or prone to bending.
The tailstock can also be used to clamp tools such as drills, reamers or countersinks. This extends the lathe’s capabilities and allows additional operations to be carried out without having to transfer the workpiece to another machine.
What is a tailstock used for?
Most commonly, the tailstock is used to support long workpieces rotating in a lathe chuck. One end of the workpiece is clamped in the spindle, whilst the other is supported by a centre set in the tailstock sleeve.
This arrangement increases the rigidity of the system and reduces vibrations during turning.
The tailstock is used, amongst other things, for machining:
- long shafts,
- axles,
- pins,
- rods,
- small-diameter components,
- workpieces requiring axial drilling.
The greater the length of the workpiece in relation to its diameter, the greater the risk of deflection during machining.
Why is it important to support the shaft in a lathe?
During turning, a cutting force acts on the workpiece. If the shaft is long and clamped only in the chuck, it may begin to bend.
This leads to a deterioration in surface finish, problems with dimensional stability and the occurrence of vibrations.
Supporting the shaft on a lathe using a tailstock helps to minimise these issues. The workpiece is stabilised at two points, thereby maintaining greater rigidity during operation.
This is particularly important when machining with a large overhang beyond the chuck.
When should the tailstock be used?
There is no single length at which a tailstock is always mandatory. The decision depends on the diameter, material, overhang of the workpiece, cutting parameters and the required accuracy.
In practice, it is advisable to use a tailstock when the shaft begins to show signs of vibration or deflection.
Support is particularly recommended when turning long and thin workpieces, at greater cutting depths, and when high dimensional accuracy is required.
If the workpiece is short and rigid, a tailstock may not be necessary.
Fixed or swivelling centre?
Various types of centres can be used in the tailstock.
A fixed centre does not rotate with the workpiece. It requires adequate lubrication of the contact surface and is mainly used for specific operations.
A rotating centre has its own bearings and rotates with the workpiece. It is more suitable for higher rotational speeds and prolonged operation.
In most typical workshop applications, a rotating centre is a very practical solution.
How do you prepare the workpiece for support?
To use the centre correctly, a centre mark must be made at the end of the spindle. It should be precisely aligned with the workpiece’s centre line and have a geometry suited to the centre used.
An incorrectly machined shoulder may cause runout, uneven support and accelerated wear of the contact surface.
Once the tailstock has been positioned, extend its sleeve and gently press the centre against the workpiece. The pressure should be sufficient to stabilise the workpiece, but not excessive.
Applying too much pressure may cause overheating, bearing overload or a change in the geometry of the slender shaft.
The tailstock as a tool holder
The tailstock is not used solely for support.
A drill chuck or a tool with a Morse taper can be mounted in its sleeve. This allows the lathe to drill directly along the axis of the workpiece.
The tailstock can be used for:
- pre-drilling,
- drilling,
- reaming,
- counterboring,
- certain threading operations.
The workpiece then rotates in the spindle, whilst the tool mounted in the tailstock is moved along the axis.
Tailstock and support – how do they differ?
The tailstock supports the workpiece at its end. However, this is not always sufficient.
With very long shafts, a fixed or movable support may also be required. This supports the workpiece closer to the cutting point and limits deflection at the centre of its length.
Therefore, the tailstock and support are not competing solutions. In demanding machining operations, they can be used simultaneously.
How do you set up the tailstock correctly?
The tailstock should be aligned with the spindle axis. If it is offset from the axis, it may cause conical rather than cylindrical turning.
It is therefore advisable to check its alignment before precision machining.
The condition of the guides and the cleanliness of the contact surfaces are also important. Dirt under the tailstock base can affect its alignment.
Once moved into the correct position, the tailstock must be securely locked onto the bed.
When is a tailstock not sufficient?
With very thin and long shafts, supporting just the end may not eliminate deflection in the central section.
In such cases, the cutting parameters should be reduced or an additional support used.
Similarly, with heavy workpieces, the permissible load on the tailstock and the centre used must be checked. The support element should not bear loads greater than those specified by the machine manufacturer.
Summary
The tailstock is primarily used to stabilise long and slender workpieces and to mount tools for drilling and other axial operations.
Proper support of the spindle on a lathe reduces vibration, minimises deflection and helps maintain the required turning accuracy. The tailstock should be used wherever the workpiece protrudes significantly beyond the chuck or where the chuck’s rigidity is insufficient.
A well-adjusted tailstock enhances safety and precision during operation, which is why it is one of the most important components of a conventional lathe.
