Everyone loves new toys, and buying a lathe can be a significant investment. Without a bit of background knowledge, the marketplace can be a bit of a minefield and perhaps confusing. Let’s take a simple look at lathes without getting too lost in the technical stuff.
Lathes are fairly basic machines and no matter their size or design, they mostly feature the same basic components as illustrated here.
- Lathe Bed
- Tool Rest
1 – Headstock
On the left of the lathe as you stand in front of it is the headstock. Its configuration varies from manufacturer to manufacturer, but they mostly have the same things in common.
The motor is attached somewhere around the headstock. On this Nova Comet lathe, it is positioned beneath the bed of the lathe and connected to a set of three gears inside the headstock.
A belt connects the motor gears to a top set of gears on the spindle. The set of gears the belt is running over will determine the speed of the spindle.
Running through the headstock is a spindle. This is generally hollow with a ‘Morse Taper’ on the right hand side to allow for certain accessories to be inserted with a friction fit. Also on this side is the spindle thread – this is where scroll chucks and other accessories are screwed onto. Depending on the size of the lathe, the spindle diameter and thread size will vary.
The distance from the centre of the spindle to the lathe bed is often known as the ‘Radius’. Multiply this by 2 and got get to the measurement known as the ‘Swing’. See below for more on this.
On the left of the spindle there is normally a Hand Wheel that is used to safely rotate to the spindle when the lathe is switched off.
The headstock may also support the control switches.
2 – Lathe Bed
Holding all the parts of the lathe together is the lathe bed. Modern lathes tend to have two flat iron bars, ground down smooth to allow the tool rest and tailstock to slide easily along it.
On this lathe, the motor is houses underneath the bed, as is the control panel on the right hand end.
Lathe beds are commonly measured by their ‘Distance Between Centres’ which is the maximum distance between the headstock and tailstock spindles when the tailstock is at its further point away from the headstock. See below for more on this.
3 – Motor
Electric motors are used (via the gears and drive belt) to turn the spindle.
The power of the motor is measured in kilowatts or horse power. 750 kilowatts is roughly equal to 1 horse power. The more horses you have, the more powerful the motor.
This Nova Comet lathe has a 750kw motor, or three quarters of one horse power.
4-5 – Banjo and Tool Rest
Between the headstock and tailstock is the ‘Banjo’ and inside that is the Tool Rest.
The Banjo (I have no idea why it is called that) sits directly on the lathe bed and can be moved into virtually any position around a work piece and be locked in place by the locking handle.
The Tool Rest is inserted into the banjo and locked into position with its own locking handle after it has been rotated, raised or lowered to where the user needs it in order to present the tool correctly to the work.
6 – Tailstock
Closest to the end of the lathe, and sliding on the lathe bed is the Tailstock.
Through the top of the tailstock runs a hollow ‘Quill’ (or Spindle) which on the left hand side (usually) has an identical Morse Taper to the headstock spindle.
The Quill can be extended out of the tailstock by turning the hand wheel on the right side of the tailstock and locked in place with the locking screw above, or to the side of it.
Various accessories can be inserted into the tailstock, but most commonly a ‘Live Centre’ is used to add additional support to the work, particularly spindle work.
The entire tailstock assembly can be slid along the lathe bed to the desired position and then locked in place with the locking handle.
Safety: All the locking handles on the banjo, tool rest and tailstock should be in their ‘locked’ position and checked before starting the lathe.
7 – Controls
Different lathes have different controls. Most modern lathes have what’s known as electronic variable control. This is where the speed of the lathe is control by a rotating switch from slow to fast. This will change depending on the gear ratio set with the drive belt in the head stock.
The control panel may also have an revolutions per minute (RPM) scale or digital readout to tell the user the speed the spindle is spinning at.
Of course there are Stop and Start buttons, too.
There may also be a ‘Forward’ and ‘Reverse’ switch. For safety, the lathe should always be run Forwards – ie, with the spindle spinning towards you. If the lathe is running backwards, any unsecured attachments on the headstock spindle are in danger of unwinding from the thread and causing injury.
With older lathes, or those at the more basic end of manufacture, there may not be any electronic variable speed. If this is the case, the speed of the lathe is increased or decreased by changing the position on the drive belt on the gears in the headstock. If there are three gears, your lathe will have three speeds, for example.
With only a few exceptions, every lathe features these parts. The parts illustrated here may well look different on other machines, or in the case of the motor and controls, they may be mounted elsewhere on the machine. And of course, other lathes may have other features.
Mini Lathes: These lathes are generally lathes with a swing less than 10″
Midi Lathes: Lathes with a swing of 10 to around 12 inches are known as Midi lathes.
Lathes with a swing of greater than 12 inches are Full Size lathes.
*These are generalisations, and may vary from manufacturer to manufacturer.
Lathes are mostly sized by their maximum capacity – their ‘Swing’ and their ‘Distance Between Centres’.
Swing: The maximum diameter the lathe can hold.
Distance Between Centres: This is the maximum distance between the headstock and tailstock spindles.
This Nova Comet lathe has a 12″ swing and 16″ between centres so would be known as a 12-16 lathe. These measurements are not the overall size of the lathe.
Lathe Bed extensions to increase the distance between centres are common accessories for lathes and bolt securely onto the right hand end of the bed and allow the tailstock to slide further away from the headstock.
Floor stands are also commonly available for mini and midi lathes, too so. These are helpful if you need to be able to move the lathe around a smaller workshop or simply prefer to keep benches clear for other work. Full Size lathes are sold complete with a set of legs as they are usually too heavy to be bench mounted.
Other accessories such as Chucks, Drive and Live Centres, different tool rests and a huge number of others all require their own grouped posts and are not necessary here.