- Practice · 3+3 marks
Slip gauges: wringing and building a size
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.
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.
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.
✓ Answer checked by Claude Opus 5.5 (high effort)
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