How to Use a Lathe: Basics

November 9, 2024 Grace Gui 0 Comments

How to operate a lathe？In this blog, I will explain a few knowledge points for you to operate a lathe novice.

Basic lathe operation

1. Basic structure and operation of the lathe

1) Introduction to the main parts of the lathe

(spindle, bed, tool holder, tailstock, etc.)

In the previous article, we talked about the main parts and important components of the lathe.

New upgrade! What is the newly defined lathe in 2025?

2) The working principle of the lathe

The working principle of the lathe is to remove excess material and form the desired shape by rotating the workpiece at high speed, driven by the spindle, while the fixed tool cuts along the surface of the workpiece. The specific operation is as follows:

Workpiece rotation

The spindle drives the workpiece to rotate at high speed, and the workpiece moves continuously around its axis to form the cutting conditions. The speed and feed rate can be adjusted to suit the material and machining accuracy.

Cutting feed

The tool is fixed to the tool holder, and by controlling the feed system, the tool can be moved along the axis (longitudinal feed) or radially (transverse feed) of the workpiece.
In the process of contact between the tool and the workpiece, the cutting force is generated so that the material is cut off and the workpiece gradually forms an outer circle, an inner hole or other complex shapes.

Cutting process

A lot of heat is generated during the cutting process, and the cooling system cools the tool and the workpiece surface to ensure machining quality.
The operator can perform roughing or finishing by adjusting the feed rate and cutting depth to meet different machining requirements.

2. Lathe installation and levelling

1) Lathe installation steps

Site preparation

Select a solid, level floor and ensure that there is sufficient working space around the lathe for easy operation and maintenance.

The floor should have good shock resistance to reduce the effect of external vibrations on the lathe and ensure machining accuracy.

Basic machining

If the volume of the lathe is large, it is recommended to pour a concrete foundation at the installation site and install anchor bolts on the foundation to secure the lathe.

Ensure that the foundation is level and has sufficient bearing capacity to support the weight of the lathe.

Positioning the lathe

Use the lifting equipment to lift the lathe to the predetermined position, carefully aligning the horizontal and vertical directions of the bed.

Adjust the anchor bolts so that the lathe can be positioned easily. Avoid installing the machine in a damp or vibrating environment.

Connecting the power and cooling systems

Connect the power supply to the lathe in accordance with the electrical standard to ensure that the voltage and current meet the requirements of the machine.

Install the cooling system and connect the coolant pipe to check that there is sufficient coolant to prevent damage to the tool due to excessive temperature.

Check the strength of each component

Make sure that the connecting bolts of the main shaft, bed, tool holder, rear seat and other components are tightened.

Check the connection status of the feed system, electrical system and lubrication system to ensure the normal operation of each system.

2) The need and steps for levelling

The purpose of levelling a lathe is to ensure that the bed and guideway are in a level condition to avoid machining errors caused by tilting or unevenness. Here are the specific steps for levelling:

Initial levelling

Place the spirit level on the guide rail of the lathe bed to check that the bed is level.
Gradually adjust the height of the anchor bolt so that the lathe is initially level.

Precise levelling

Select several measuring points on the bed, usually including both ends and the centre of the bed, and make sure that all points are level by multi-point adjustment.
Repeat the levelling of the bed and guide with a more accurate level (such as an electronic level) to ensure that the entire bed is level.

Diagonal levelling

Set the diagonal level of the bed and check the levelness in the diagonal direction to prevent the bed from twisting in the diagonal direction.
Measure the level at the four corners of the bed and adjust the anchor bolts to ensure that the diagonal direction is fully balanced.

Spindle centre calibration

Clamp the standard workpiece, check the concentricity and straightness of the spindle centre, and ensure that the workpiece and tool remain centred during machining.
Fine tune the spindle centre deviation to ensure machining accuracy and to avoid spindle offset resulting in workpiece eccentricity.

Tighten the anchor bolts

After confirming that the lathe is level, tighten each anchor bolt in turn to prevent loosening during operation.
Finally, carry out a comprehensive inspection of the lathe, confirming the levelling data and ensuring the stability of the lathe level.

3. Specifications for safe lathe operation

Safety Precautions for Lathe Operation：

Equipment inspection

1）Before each use, check that the main shaft, tool holder, tailstock, feed system, cooling system and other key components of the lathe are in good condition.

2）Check that the tool is firmly installed and that the blade is sharp, to prevent safety hazards caused by loosening or blade damage.

Tool holding

1）Grip the workpiece firmly in the chuck or jig to ensure that it is correctly installed and will not come loose.

2）When machining large or long parts, the rear seat or bracket should be installed to provide additional support to prevent the workpiece from falling off during rotation.

The machine starts and stops

1）Before starting the lathe, make sure that the work area is clean and that all tools and workpieces are properly installed.

2）Do not adjust the workpiece or the tool during the rotation or cutting process of the lathe; if you need to make adjustments, first close the machine and stop it completely.

Feed and depth of cut

1）The cutting speed and feed should be adjusted to suit the workpiece material, size and type of tool to avoid the risk of overloading.

2）Avoid cutting too deep to prevent the tool from breaking or the workpiece from flying out and causing an accident.

Cutting fluid and cooling system

1）When using coolant, ensure that the cooling system is working properly to prevent coolant from splashing onto the operator’s body or eyes.

2）Do not touch the workpiece directly with your hand during turning to avoid burns or cuts caused by high temperatures or sharp edges.

Keep the work area clean and tidy

1）During operation, keep the floor and equipment free of oil and debris to prevent slipping or impact.

2）It is forbidden to place tools and debris on the lathe or near the tool holder during operation to avoid slipping or interfering with the operation.

Safety precautions

Know the position of the emergency stop button on the lathe so that the machine can be stopped quickly in an emergency.

Turning operation basis

1. Basic operation of lathe

1) Checking the work before starting the step

2) Tool installation and adjustment

3) Starting and feeding the cutting process of the lathe

2. Lathe cutting speed calculation

1) Cutting speed calculation formula

The cutting speed (VVV) refers to the relative linear speed between the cutting edge of the tool and the contact part of the workpiece, usually expressed in metres per minute (m/min). The cutting speed can be calculated using the following formula

V=π×D×N1000V = \frac{\pi \times D \times N}{1000}V=1000π×D×N where:

VVVV is the cutting speed (unit: m/min);
DDD is the diameter of the workpiece (unit: mm);
NNN is the spindle speed (unit: rpm, i.e. revolutions per minute);
π≈1416\pi \approx 3.1416π≈3.1416.

Formula converted to spindle speed:

If the cutting speed VVV and the workpiece diameter DDD are known, the required spindle speed NNN can be calculated:

N=1000× vπ ×DN = \frac{1000 \times V}{\pi \times D}N=π×D1000×V This formula helps to determine the best cutting speed and spindle speed for different materials and diameters to achieve the purpose of efficient machining.