HEAD STOCK

Head stock

HEADSTOCK

     The headstock is normally mounted rigidly to the bed and holds all the mechanisms, like combinations of pulleys or gears, controlling etc. Also it contain spindle. The spindle can be made to turn at different speeds.

HEADSTOCK SPINDLE

     The end of the headstock spindle is usually machined so that it can carry a faceplate,chuck,drive plate, internal or external collets – or even special attachments designed for particular jobs. In turn, these attachments hold the workpiece that is going to be machined.

BACKGEAR
As its name implies, backgear is a gear mounted at the back of the headstock (although in practice it is often located in other positions) that allows the chuck to rotate slowly with greatly-increased torque (turning power). Backgeared lathes are sometimes referred to a “BG” or “BGSC” – the latter meaning “backgeared and screwcutting”. At first, the ability to run a workpiece slowly might seem unnecessary, but a large-diameter casting, fastened to the faceplate and run at 200 rpm would have a linear speed at its outer edge beyond the turning capacity of a small lathe. By engaging backgear, and so reducing the speed but increasing the torque, even the largest faceplate-mounted jobs can be turned successfully.

LEADSCREW
      important part on a lathe machine. Originally termed a “master thread”, or described as the “leading screw”, but now always referred to as the “leadscrew”, this is a long threaded rod normally found running along the front of the bed or, on some early examples running between the bed ways down the bed’s centre line. By using a train of gears to connect the lathe spindle to the leadscrew  – and the leadscrew to the lathe carriage the latter, together with its cutting tool, could be forced to move a set distance for every revolution of the spindle.

Apron

Apron Mechanism

SADDLE
The casting that fits onto the top of the bed. The term saddle is a self-explanatory, that is it slides along it is known, almost universally, as the “Saddle”
APRON
    The vertical, often flat and rectangular “plate” fastened to the front of the “Saddle” is known as the “Apron”. It carries a selection of gears and controls that allow the carriage to be driven (by hand or power) up and down the bed. The mechanism inside can also engage the screwcutting feed and various powered tool feeds, should they be fitted. The leadscrew, and sometimes a power shaft as well, are often arranged to pass through the apron and provide it with a drive for the various functions.

     All screw-cutting lathes have what is commonly-called a “half-nut” lever that closes down one and sometimes two halves of a split nut to grasp the leadscrew and provide a drive for screwcutting.
Apron design can be roughly divided into “single-wall” and “double-wall” types. The “single-wall” apron has just one thickness of metal and, protruding from it (and unsupported on their outer ends) are studs that carry gears. The “double-wall” apron is a much more robust structure, rather like a narrow, open-topped box with the gear-carrying studs fitted between the two walls – and hence rigidly supported at both ends. This type of construction produces a very stiff structure – and one that is far less likely to deflect under heavy-duty work; another advantage is that the closed base of the “box” can be used to house an oil reservoir the lubricant ion which is either splashed around or, preferably, pumped to supply the spindles, gears and even, on some lathes, the sliding surfaces of the bed and cross slide as well.