The Content Of The Article:

Modeling, general mechanics, machining a broken part... The possibilities of the metal lathe are so important that it would be a real shame to deprive oneself of it.

This machine tool is basically designed to shape cylinders, such as axles or driveshafts.

The workpiece, rotated in a horizontal plane, is worked thanks to a cutting tool clamped on the machine (unlike the wood lathe). Most of today's towers have a steerable trolley for making cones.

Another essential function, the machine allows to machine threads by combining rotation of the workpiece and movement of the tool.

Finally, another possibility to know, a ride can also help a handyman for small milling.

## Find the right speed

To correctly machine the metals, it is necessary to determine the rotation speed (Vr) of the mandrel, expressed in revolutions per minute, as a function of the cutting speed (Vc) expressed in meters per minute and the diameter of the piece (D) to machined.
For that, it is necessary to apply the following formula:

Vr = Vc / Π (ft) x D.

However, on amateur tours, we must, alas, be satisfied with an approximation.
Remember that with tools HSS (high speed steel) or carbide pellet, easy to use for beginners, the rotation speed is:
- 120 m / min for aluminum,
- 20m / min for steel and cast iron
- 30m / min for brass and bronze.

## Prepare the metal lathe

Adjust the movement of the trolley by adjusting the backgauge (small wedge) of play catch. Neither too hard nor too loose.

Adjust also steering wheels, trolleys, scabbard and lead screw, if applicable. Tight, they are too hard, loose, they have play.

Observe the assembly order of the jaws in the chuck. They must meet at the center of the latter.

## Machine a short piece

The short pieces are taken at one end in the three-jaw chuck.

## Machine a long piece

The long pieces are taken at both ends.
For more precision, train the room with a knock.

To work at the end of a long piece, use a fixed bezel to support the blank to be machined.

## To machine a bowl

Centering cups are machined with a drill chuck.
The room is blocked by the fixed telescope.

Do not pull out the sleeve of the mobile doll too much to avoid cantilevers.

Adjust the speed of the lathe by moving the drive belt to the correct pulley.

The cutting edge of the tool must be at the height of the axis of rotation. To adjust it, align with the tailstock.

The lead screw allows the automatic advance of the support of the tool (straggler) along the bench, for a regular machining.