Lathe Tools And Uses

The spindle rotates by means of an electric motor and a system of belts and pulleys and gear trains. Altering the setup of the drive train varies the speed. The part is secured in the rotating spindle by various means including three-jawed chucks, collets and centres. A tailstock fixes the end of the part with a centre. It can also be used to hold tools, which can be used for drilling, threading, reaming or cutting tapers. Different length parts can be accommodated easily by moving the tailstock to different sections of the bed to which it is attached.

A carriage holds and controls the tool used for cutting. It consists of a saddle, which can slide along the bed, an apron from which the tool is fed against the rotating part, a cross slide which regulates the traversing motion of the tool, a tool compound which enables the tool to be set at various angles and a tool post slot that houses the tool post.

The shape of the tool used varies depending upon the type of work required. Facing tools are ground to have sufficient clearance, finishing tools have a rounded nose to provide a fine finish, roughing tools leave more surface area behind for support to enable deeper cuts. There are also left hand cutting tools and tools for cutting aluminum which are angled differently again with the cutting edge above centre to reduce vibration. The tool is secured on the top of the tool post by bolts or alternatively by a quick release lever.

Moving the tool is accomplished by hand rotation of a slide mechanism or sometimes by an automatic or power feed, depending on the model of lathe. Another movement axis is the compound, which enables cuts of varying angles to be made. All these movements can be measured against a micrometer dial indicator to allow for minute adjustments.

The cutting speed of the machine is the rotation of the part against the tool measured in feet per minute. Another measurement is the feed rate, which is the distance of tool travel during one revolution of the part. The variables, applied to the cutting speed and feed, dictate the smoothness of the finished product. Therefore, the type of material to be cut is a deciding factor when determining the correct speed and feed rate. Other factors to be considered are the depth of the cut and condition of the tools and the lathe. Trial and error is sometimes the best way to determine the correct settings to achieve the best result as all of these factors vary greatly among different machines.

During operation the lathe reduces the diameter of a part to the required dimension with a roughing or finishing tool. A flat face can be achieved, which is perfectly perpendicular to the axis of the cylindrical section using a facing tool. A parting tool is used for manufacturing narrow grooves and for cutting parts. A parting tool must be positioned so that it will clear the part throughout the horizontal movement and so that the tip of the tool is aligned with the exact centre of the part. Drilling is another operation, which can be conducted on a lathe with the holes accurately aligned with the centre axis of the part. Boring is similar to drilling in that a hole is made through the centre of the part but with boring, the hole is enlarged with the tip of the tool being extended into the hole and wound outwards. A part can have an external thread cut with a die and internal threads can be created using a tap. Another method for creating a thread is to cut the thread on the lathe using a special cutting tool with an angled nose.

Michael Russell

Your Independent guide to Lathe