---
title: "Slip gauges: wringing and building a size"
subject: "Workshop Technology"
chapter: 4
key: "semester_2/workshop_technology:slip-gauge-wringing-build-up"
source: https://www.bctengineer.com/q/semester_2/workshop_technology/slip-gauge-wringing-build-up
site: BCT Engineering
---

# Slip gauges: wringing and building a size

Workshop Technology · Chapter 4: Measuring and Gauging

- Asked in: year not given, 3+3 marks
- Video: [Slip Gauges explained in hindi || what is slip gauge || metrology and instrumentation || slip gauge](https://www.youtube.com/watch?v=sO9k7waLLws) — Gear Institute Mechanical Engineering Videos and Physics by Gear Institute
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/workshop_technology/slip-gauge-wringing-build-up
- Whole chapter: https://www.bctengineer.com/md/semester_2/workshop_technology/chapter-4

## Question

What are slip gauges (gauge blocks)? Explain wringing. Using a set of 87 pieces (1.001 to 1.009 in steps of 0.001 mm; 1.01 to 1.49 in 0.01 mm; 0.5 to 9.5 in 0.5 mm; 10 to 100 in 10 mm), select the minimum number of blocks to build 48.325 mm.

## Short answer

Slip gauges are lapped blocks of precise thickness. Wringing is sliding two clean blocks together with a twist, causing adhesion by molecular attraction. Minimum blocks for 48.325 mm: 1.005 mm, 1.32 mm, 6.0 mm, and 40.0 mm, summing to 48.325 mm.

## Answer

#### Slip gauges
Slip gauges are rectangular blocks of hardened steel, carbide or ceramic, lapped flat and parallel to a very high accuracy, with the two working faces a precise distance apart. They are the working standard of length in workshops, used to calibrate other gauges, to set sine bars and comparators, and for precision inspection. Grades: 00 (reference and calibration), 0 (inspection), 1 and 2 (workshop).

#### Wringing
Wringing is sliding two clean blocks together with light pressure and a twisting motion so that they stick together.
- The faces are lapped so flat that a thin film of oil or moisture, together with molecular attraction, holds them with a force of many newtons; the joint thickness is nearly zero (about 0.01 micron).
- Procedure: clean the faces, place one block across the other at right angles, then slide and rotate it until the blocks are aligned.
- It lets several blocks be combined to give any size, with the errors adding up only slightly.

#### Building 48.325 mm (87-piece set)
Remove the decimal places starting from the last digit, using one block each time.

| Step | Remaining size | Block taken |
|---|---|---|
| 1 | 48.325 | 1.005 (removes the 0.005) |
| 2 | 47.320 | 1.32 (removes the 0.32) |
| 3 | 46.000 | 6.0 |
| 4 | 40.000 | 40.0 |

Check: 1.005 + 1.32 + 6.0 + 40.0 = 48.325 mm.

**Answer: four blocks - 1.005 + 1.32 + 6.0 + 40.0 = 48.325 mm.**

## Check yourself

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

1. Slip gauges are mainly used as
   A. Cutting tools
   B. A working standard of length for calibration and precision inspection
   C. Clamping devices
   D. Surface roughness testers
   Answer: B. They are lapped blocks serving as the workshop standard of length, used to calibrate gauges and set instruments. (Key point: Use of slip gauges)

2. What is wringing?
   A. Welding blocks together
   B. Sliding clean lapped blocks together with a twisting motion so they stick
   C. Bolting blocks together
   D. Heating blocks to join them
   Answer: B. Very flat faces held by a thin oil or moisture film and molecular attraction stick together when slid and twisted. (Key point: Wringing)

3. How is a size built up from a slip gauge set to use the fewest blocks?
   A. Start from the largest block
   B. Eliminate the last decimal digit first, then work upwards, one block each time
   C. Use only blocks with equal sizes
   D. Choose random blocks and adjust
   Answer: B. Remove the decimal places from the last digit upwards, each time taking one block. (Key point: Build-up method)

4. Which combination builds 48.325 mm with four blocks?
   A. 1.005 + 1.32 + 6.0 + 40.0
   B. 1.005 + 1.3 + 6.0 + 40.0
   C. 1.002 + 1.32 + 7.0 + 40.0
   D. 1.005 + 1.32 + 5.0 + 40.0
   Answer: A. 1.005 + 1.32 + 6.0 + 40.0 = 48.325 mm. (Key point: Blocks for 48.325 mm)

## Related in Workshop Technology

- [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
- [Hand tapping and tap drill size](https://www.bctengineer.com/question.md?key=semester_2%2Fworkshop_technology%3Ahand-tapping-tap-drill) — Workshop Technology, chapter 3
- [Thread cutting on lathe and change gears](https://www.bctengineer.com/question.md?key=semester_2%2Fworkshop_technology%3Alathe-thread-cutting-change-gears) — Workshop Technology, chapter 6

## Related in other subjects

- [Slip gauges: wringing and building a stack](https://www.bctengineer.com/question.md?key=semester_3%2Fmetrology%3Aslip-gauge-wringing-and-stack) — Metrology, chapter 4