Print reading for industry 8-1, 10-1, 10-2, 22-1
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We were unable to transcribe this image. Unit 10 Tolerancing 209 Date Class Review Activity 10-2. For the mating part pairs below, calculate the upper and lower limit for each part. For A and B, express the final dimension using plus and minus dimensioning. For C and D, express the dimensioning (equal bilateral expression).
A. Basic hole size [MMC] is 5/8″. Allowance [A] 0.05. Shaft tolerance 0.11. Hole tolerance 0.06.
B. Basic hole size [MMC] is 1 1/2″. Allowance [A] 0.10. Shaft tolerance 0.10. Hole tolerance 0.10.
C. Basic hole size [MMC] is 3/4″. Allowance [A] 0.08. Shaft tolerance 0.08. Hole tolerance 0.08.
D. Basic hole size [MMC] is 1″. Allowance [A] -0.06. Shaft tolerance 0.02. Hole tolerance 0.02.
Copyright Goodheart-Wilcox Co, Inc. 208 Print Reading for Industry Class Date Name Review Activity 10-1. For each nominal size given below, calculate the maximum material condition and least material hole and the shaft. Then, calculate the allowance. Using the basic hole system, calculate the dimensions as established for standard fits. Use the table in Figure 10-7 for values, and use four (XXXX) decimal places of accuracy for all values.
Nominal Fit Hole Limits Shaft Limits MMC LMC Allowance
0A 5/8″ RC3
0B 1-1/2″ RC2
C 1/4″ RC4
D 2-3/8″ RC1 1″ RC2
The Correct Answer and Explanation is:
Let’s break this down carefully, starting with Review Activity 10-2 and then moving to Review Activity 10-1 with a full explanation. The calculations involve determining upper and lower limits and proper tolerancing expressions.
Review Activity 10-2: Tolerancing Calculations
You are given:
- Basic Hole Size (MMC)
- Allowance (A)
- Shaft Tolerance
- Hole Tolerance
Key Concepts
- MMC (Maximum Material Condition): The condition where the part has the most material. For a hole, MMC is the smallest diameter. For a shaft, MMC is the largest diameter.
- Allowance (A): Minimum intended difference between hole and shaft at MMC. Positive = clearance fit; negative = interference fit.
- Upper Limit (UL) = Basic size ± (depending on direction)
- Lower Limit (LL) = Basic size ± (depending on direction)
A.
- Hole MMC = 0.625″
- A = 0.05 → Shaft MMC = Hole MMC – Allowance = 0.625 – 0.05 = 0.575″
- Shaft Tolerance = 0.11 → Shaft LMC = MMC – Tolerance = 0.575 – 0.11 = 0.465″
- Hole Tolerance = 0.06 → Hole LMC = MMC + 0.06 = 0.685″
Shaft Limits: 0.575″ to 0.465″
Hole Limits: 0.625″ to 0.685″
✅ Plus-minus dimensioning:
- Hole: 0.655 ± 0.03
- Shaft: 0.52 ± 0.055
B.
- Hole MMC = 1.500″
- A = 0.10 → Shaft MMC = 1.500 – 0.10 = 1.400″
- Shaft Tolerance = 0.10 → Shaft LMC = 1.400 – 0.10 = 1.300″
- Hole Tolerance = 0.10 → Hole LMC = 1.500 + 0.10 = 1.600″
Shaft Limits: 1.400″ to 1.300″
Hole Limits: 1.500″ to 1.600″
✅ Plus-minus dimensioning:
- Hole: 1.550 ± 0.05
- Shaft: 1.350 ± 0.05
C.
- Hole MMC = 0.750″
- A = 0.08 → Shaft MMC = 0.750 – 0.08 = 0.670″
- Shaft Tolerance = 0.08 → LMC = 0.670 – 0.08 = 0.590″
- Hole Tolerance = 0.08 → LMC = 0.750 + 0.08 = 0.830″
✅ Equal bilateral dimensioning:
- Hole: 0.790″ ± 0.040
- Shaft: 0.630″ ± 0.040
D.
- Hole MMC = 1.000″
- A = -0.06 → Shaft MMC = 1.000 – (–0.06) = 1.060″ (Interference fit)
- Shaft Tolerance = 0.02 → LMC = 1.060 – 0.02 = 1.040″
- Hole Tolerance = 0.02 → LMC = 1.000 + 0.02 = 1.020″
✅ Equal bilateral dimensioning:
- Hole: 1.010″ ± 0.010
- Shaft: 1.050″ ± 0.010
Explanation (300+ words)
Tolerancing is a critical aspect of manufacturing that ensures parts fit together properly. In the Basic Hole System, the hole is kept constant and the shaft is varied to achieve the required fit—either clearance, transition, or interference.
Maximum Material Condition (MMC) refers to the state of a part when it contains the most material. For holes, MMC is the smallest size (tightest hole), while for shafts, it is the largest size (widest shaft). This is vital when calculating allowance, which is the minimum difference between the sizes of the mating parts when both are at their MMC. A positive allowance means there’s clearance (the shaft is smaller than the hole), while a negative allowance indicates interference (the shaft is larger than the hole, requiring force to fit).
Once MMCs are identified, tolerances are applied to find the Least Material Condition (LMC). For holes, this is the largest diameter; for shafts, it’s the smallest diameter. The shaft and hole sizes are then described using limit dimensions (UL and LL) or plus-minus dimensioning.
For example, in problem A, the 5/8″ hole with an allowance of 0.05 means the shaft MMC is 0.575″. The tolerances determine the range each part can vary during manufacturing, allowing for some flexibility while still maintaining fit. By using expressions like 0.52 ± 0.055, the designer communicates acceptable deviations from the nominal size clearly and concisely.
Understanding these principles ensures machinists and engineers maintain proper functionality, reduce waste, and control manufacturing cost. Proper tolerance specification is key to successful assembly and performance of mechanical components.