Module 2: Assessment Quiz

Module: U8M2 - Metal Lathe Operations Duration: 20-30 minutes Passing Score: 70%

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What is the first step before performing any turning operation on the metal lathe?

Select the cutting tool

Calculate the RPM

Verify the workpiece is securely held, the chuck key is removed, and all guards are in place

Turn on the coolant pump

Submit

Explanation: Safety verification is always the first step. A loose workpiece or forgotten chuck key can cause catastrophic injury. Guards protect against flying chips and coolant splash.

What operation produces a flat surface perpendicular to the lathe axis?

Turning

Facing

Boring

Knurling

Submit

Explanation: Facing cuts across the end of the workpiece from the outside diameter toward the center (or center toward the outside), producing a flat surface perpendicular to the axis of rotation.

When turning a stepped shaft, which diameter should be turned first?

The smallest diameter

The largest diameter, then progress to smaller diameters

Any diameter—order does not matter

The middle diameter

Submit

Explanation: Turning the largest diameter first maintains maximum workpiece rigidity. As you remove material to create smaller diameters, you are working with less material to support cutting forces. Turning small diameters first creates thin, flexible sections that deflect under cutting pressure.

What is the function of the cross slide on a metal lathe?

To rotate the tool post

To move the tailstock

To move the cutting tool radially (perpendicular to the lathe axis) for controlling depth of cut and facing operations

To change spindle speed

Submit

Explanation: The cross slide moves the cutting tool in the X-axis (toward and away from the workpiece center). Each graduation on the cross slide dial typically represents 0.001" of tool movement. On most lathes, the diameter changes by twice the cross slide movement (since you are cutting on one side only).

What is the purpose of the compound rest in turning operations?

To lock the carriage in position

To hold the chuck

To provide angular tool movement for chamfers, tapers, and threading operations

To feed coolant to the cutting zone

Submit

Explanation: The compound rest can be rotated to any angle relative to the workpiece axis. This allows the tool to be fed at an angle for short tapers and chamfers. For threading, the compound is typically set to 29° or 29.5° to feed along one flank of the thread form.

What lathe operation uses a single-point tool to create external or internal screw threads?

Knurling

Parting

Threading (single-point threading)

Boring

Submit

Explanation: Single-point threading uses a ground or inserted thread-form tool fed at a precise pitch using the lead screw and half-nut. The lathe's gear train is set to synchronize spindle rotation with carriage travel to match the desired thread pitch (e.g., 20 TPI, 1.5mm pitch).

When parting off (cut-off) on the lathe, what is the correct tool height?

Above center

Well below center

Exactly on center or very slightly above (0.005-0.010")

Tool height does not matter for parting

Submit

Explanation: A parting tool must be set precisely on center height. If below center, the tool will rub instead of cutting and can climb over the workpiece. If too far above center, it can dig in aggressively. The tool should be perpendicular to the workpiece axis with no angular offset.

What is "boring" on the lathe?

Drilling a hole through the spindle bore

Cutting external threads

Enlarging and truing an existing hole using a single-point boring bar

Making the operation less interesting

Submit

Explanation: Boring uses a boring bar (a cantilevered single-point tool) inserted into an existing hole to enlarge it to a precise diameter with good surface finish and concentricity. Boring corrects issues that drilling cannot control: hole diameter accuracy, roundness, straightness, and surface finish.

What causes "chatter" during a turning operation?

Dull cutting tool only

Incorrect coolant mixture

Vibration from insufficient rigidity—tool overhang too long, workpiece unsupported, worn bearings, or excessive depth of cut

Using the wrong type of metal

Submit

Explanation: Chatter is self-excited vibration that produces a distinctive pattern of regularly-spaced marks on the workpiece surface. Common causes include: excessive tool overhang, unsupported workpiece length, worn machine bearings, aggressive cutting parameters, or resonance between the tool and workpiece. Increasing rigidity and adjusting speed/feed typically eliminates it.

When drilling on the lathe using a drill chuck in the tailstock, what is the maximum recommended drill depth per peck?

Full depth in one plunge

1-2 times the drill diameter per peck, then retract to clear chips

0.010" per peck

5 times the drill diameter

Submit

Explanation: Peck drilling (advancing 1-2 drill diameters, then retracting to clear chips) prevents chip packing, which causes drill overheating, deflection, and breakage. Deeper holes require more frequent pecks and coolant flooding.

What is a steady rest used for on the metal lathe?

To hold the cutting tool

To replace the tailstock

To support long workpieces at an intermediate point along their length to prevent deflection during turning

To measure workpiece diameter

Submit

Explanation: A steady rest clamps to the lathe bed and provides three-point support to the workpiece at a position between the chuck and tailstock. It prevents long, slender workpieces from deflecting away from the cutting tool, which would cause taper, chatter, and dimensional inaccuracy.