Machine guides › General manual lathe

How to operate a manual lathe

General steps that apply to most manual centre lathes. Your own machine’s manual comes first.

Before you switch on

• Clear the bed, cross-slide and chip tray of tools, rags and swarf. Nothing should be able to fall into the chuck.
• Check oil levels in the sight glasses (headstock, apron and gearbox, where fitted) and oil the slideways and any oil points your manual lists.
• Make sure the work is held securely and the chuck key is out of the chuck. Make a habit of never letting go of the key while it is in the chuck.
• Turn the chuck by hand one full turn to check the work, jaws and tool clear the carriage, toolpost and tailstock.
• Check the guards and emergency stop work. Wear eye protection; roll up sleeves, take off gloves, rings and watches, and tie back long hair.

Setting the speed

• Work out the spindle speed from the cutting speed for the material and the work diameter with the RPM calculator. Large work and hard materials need lower speeds.
• Change gears, belts or speed ranges only with the spindle stopped, unless your manual says otherwise. If the levers will not engage, turn the chuck slightly by hand rather than forcing them.
• If you are unsure, start slower. You can always go faster once the cut looks and sounds right.

Feeds: the leadscrew and the feed shaft

• Many lathes have two drives to the carriage: a feed shaft for ordinary turning and facing feeds, and a leadscrew used only for screwcutting. Using the feed shaft for general turning keeps wear off the leadscrew. Smaller lathes may use the leadscrew for both.
• Select the feed rate on the gearbox or change gears (the chart on the machine tells you the settings), then choose the direction. The speeds and feeds calculator suggests a starting feed.
• Do not engage the power feed and the half-nuts at the same time. Most lathes have an interlock, but don’t rely on it.
• Know where the carriage will stop. Disengage the feed well before the chuck or a shoulder; power feed will not stop by itself.

Threading: engaging the half-nuts

• Set the gearbox or change gears for the pitch (see the thread calculator and change gears), and use a slow speed until you are confident.
• Close the half-nuts on the correct mark of the thread dial for the pitch you are cutting. If the thread pitch does not match the leadscrew system (metric on an imperial leadscrew, or the reverse), leave the half-nuts closed and reverse the spindle to return.
• Withdraw the tool at the end of each pass before you stop or reverse. The full method is in the screwcutting guide.

Chuck safety

• Never exceed the chuck’s maximum speed, and slow down for large or unbalanced work.
• Keep the length of work sticking out short; support long work with the tailstock centre or a steady.
• Fit or remove chucks only with the machine isolated, and follow your manual for the spindle nose type (threaded, camlock or taper). Protect the bed with a board when changing chucks.
• Never reach over a turning chuck, and never try to stop it by hand.

Shutting down

• Withdraw the tool, disengage feeds and half-nuts, and stop the spindle. Let it come to rest on its own.
• Set speed controls to their lowest or neutral position if your manual recommends it, and isolate the machine at the wall.

Cleaning and oiling

• Clear swarf with a brush or hook, never with bare hands or compressed air, which drives chips into slideways and eyes.
• Wipe the slideways and leadscrew and leave a light film of oil. Oil the points on your manual’s lubrication chart at the intervals it gives, and use the oil grades it specifies.
• Note anything unusual (noise, play, leaks) and fix it before the next job.