---
title: "Basic lathe operations"
subject: "Workshop Technology"
chapter: 6
key: "semester_2/workshop_technology:lathe-operations-explained"
source: https://www.bctengineer.com/q/semester_2/workshop_technology/lathe-operations-explained
site: BCT Engineering
---

# Basic lathe operations

Workshop Technology · Chapter 6: General Machining Processes “Chip-forming”

- Asked in: year not given, 6 marks
- Video: [All Lathe Machine Operations: Turning, Facing, Taper Turning, Boring, Knurling, Tapping, Forming](https://www.youtube.com/watch?v=km6ickQglVY) — Shubham Kola
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/workshop_technology/lathe-operations-explained
- Whole chapter: https://www.bctengineer.com/md/semester_2/workshop_technology/chapter-6

## Question

Explain the following lathe operations with sketches: (a) facing, (b) straight turning, (c) parting off, (d) knurling, (e) boring.

## Short answer

Facing: cross-feed to flatten ends. Straight turning: axial feed reduces diameter. Parting off: radial feed with narrow blade cuts blank. Knurling: rollers displace metal for grip. Boring: single-point bar enlarges a hole. All use appropriate feed, speed, and rigid setup.

## Answer

#### (a) Facing
Machining the end of the job flat and perpendicular to its axis. The tool is fed from the outside inward (or from the centre outward) with the cross slide, with the carriage locked.

```text
  chuck |=========|
        |  job    |<-- tool moves across
```

#### (b) Straight turning
Reducing the diameter of a cylindrical job. The tool moves parallel to the axis with the carriage feed. Roughing uses a large depth of cut and feed; finishing uses a small depth and feed with a fine nose radius.

```text
  chuck ||====================|
        ||   job (rotating)   |
                     [tool]
              <----- feed parallel to the axis
```

#### (c) Parting off
Cutting a finished piece off the bar using a narrow, blade-type parting tool fed radially by the cross slide. The tool is set on the centre line and used with a low feed and coolant, with a short overhang and a rigid set-up to avoid chatter.

```text
  chuck ||========|  |=====|
        ||  bar   |  | piece being cut off
                   ^
            parting tool fed radially
```

#### (d) Knurling
Producing a diamond (cross) or straight pattern on the surface for grip (handles, nuts). A knurling tool with two hardened rollers is pressed into the rotating job at low speed (about 1/3 of the turning speed) with oil. The metal is displaced, not cut, so the diameter increases slightly.

```text
  chuck ||=#=#=#=#=#=#========|
        ||  job (knurled part) |
             (o)(o)  <- knurling rollers pressed in
```

#### (e) Boring
Enlarging an existing hole with a single-point boring bar held in the tool post. The job is rotated in a chuck and the tool feeds axially inside the hole. It gives accurate size and concentricity; the bar should be short and rigid.

```text
  chuck ||==========|
        ||  ______  |
        || |    <===|===== boring bar (fed along the axis)
        || |______  |
        ||==========|
```

Other operations: drilling and reaming (through the tailstock), taper turning, thread cutting, grooving, chamfering.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. In facing, the tool is fed
   A. Parallel to the axis by carriage feed
   B. Across the job with the cross slide, with the carriage locked
   C. Axially inside a hole
   D. By swivelling the tailstock
   Answer: B. Facing makes the end flat and perpendicular to the axis using cross slide movement. (Key point: Facing)

2. For parting off, the tool should be
   A. Set above centre with high feed
   B. Set on the centre line, with low feed and coolant, kept rigid to avoid chatter
   C. Fed along the axis
   D. Used without coolant
   Answer: B. A narrow parting tool is fed radially on centre height with low feed and coolant to avoid chatter. (Key point: Parting off)

3. Knurling produces a grip pattern by
   A. Cutting chips from the surface
   B. Displacing metal with hardened rollers, slightly increasing diameter
   C. Grinding the surface
   D. Boring
   Answer: B. The rollers press the pattern in; the metal is displaced, not cut, so diameter increases slightly. (Key point: Knurling)

4. Boring on a lathe is
   A. Making a new hole with a twist drill
   B. Enlarging an existing hole with a single-point boring bar for accurate size and concentricity
   C. Cutting a finished piece off the bar
   D. Turning an external taper
   Answer: B. A single-point boring bar enlarges an existing hole; it should be short and rigid. (Key point: Boring)

## Related in Workshop Technology

- [Basic forging operations](https://www.bctengineer.com/question.md?key=semester_2%2Fworkshop_technology%3Aforging-operations-explained) — Workshop Technology, chapter 9
- [Taper turning: set-over and compound angle](https://www.bctengineer.com/question.md?key=semester_2%2Fworkshop_technology%3Ataper-turning-setover-numerical) — Workshop Technology, chapter 6
- [Turning time and metal removal rate](https://www.bctengineer.com/question.md?key=semester_2%2Fworkshop_technology%3Alathe-turning-time-mrr-numerical) — Workshop Technology, chapter 6
- [Sheet metal cutting and forming operations](https://www.bctengineer.com/question.md?key=semester_2%2Fworkshop_technology%3Asheet-metal-operations-explained) — Workshop Technology, chapter 8

## Related in other subjects

- [Lathe operations, taper turning and turning calculations](https://www.bctengineer.com/question.md?key=semester_4%2Fmanufacturing_and_production_processes%3Alathe-operations-taper-turning-numerical) — Manufacturing and Production Processes, chapter 7
- [SCR from complementary BJTs; turning off SCR](https://www.bctengineer.com/question.md?key=semester_4%2Fadvanced_electronics%3Acomplementary-bjt-scr-turn-off) — Advanced Electronics, chapter 7
- [Data structure and basic operations](https://www.bctengineer.com/question.md?key=semester_4%2Fdata_structure_and_algorithm%3Adata-structure-basic-operations) — Data Structure and Algorithm, chapter 1
- [Linked list and its basic operations](https://www.bctengineer.com/question.md?key=semester_4%2Fdata_structure_and_algorithm%3Alinked-list-and-operations) — Data Structure and Algorithm, chapter 4