Telecurso 2000 - Metrologia - 02 Medidas e Conversões
Understanding Measurement Conversions in Metalworking
Introduction to Measurement Units
- The speaker is converting inches to millimeters for a company order, highlighting the importance of unit conversion in metalworking.
- Inches and millimeters are the most commonly used measurement units in metalworking; today's lesson will cover the English measurement system and common conversions.
The English Measurement System
- Discussion about verifying measurements, emphasizing that precision is crucial when dealing with measurements.
- A colleague mentions that inches are becoming less common, but they remain prevalent in metalworking alongside millimeters.
- The speaker explains the historical context of the yard as a standard unit established by King Henry I in the 12th century.
Historical Context of Measurements
- The yard was originally defined as the distance from a king's nose to his outstretched thumb; this definition has evolved over time.
- In 1959, the yard was standardized based on meters, equating to 91.44 cm.
- Legal definitions were established for relationships between yards, feet (12 inches), and miles (1 mile = 1760 yards).
Understanding Fractions and Decimals
- Explanation of how to read fractional inches: examples include 1/44 inch, 1/8 inch, etc., which can complicate calculations due to their imprecision.
- Introduction of decimal fractions for easier calculations; these include subdivisions like thousandths and millionths of an inch.
Practical Applications of Conversions
- Emphasis on using decimal values instead of fractions for accuracy; example given includes expressing measurements like "725 thousandths of an inch."
- A problem arises regarding converting drawings from inches to millimeters; understanding conversions is essential for accurate production.
Conversion Techniques
- Discussion on how to convert fractional inches into millimeters by multiplying by 25.4 (e.g., converting 2" and 3/8").
- Steps outlined for converting mixed fractions into millimeters through multiplication followed by addition.
Conversion of Measurements: Understanding Fractional and Decimal Inches
Introduction to Measurement Conversion
- The speaker introduces the concept of converting millimeters (MM) to fractional inches, using a denominator of 128.
- An example is provided with 12.7 MM converted by dividing by 25.4 and multiplying by 128, resulting in approximately 64/128 inches.
Practical Conversion Techniques
- The conversion process involves multiplying the value in millimeters by a factor derived from the relationship between 128 and 25.4, which equals approximately 5.04.
- For instance, converting again with 12.7 MM yields about 64/128 inches after simplification.
Converting Decimal Inches to Fractional Inches
- To convert decimal inches (e.g., .125 inches), one can multiply by the fraction equivalent (e.g., using 128 as a denominator).
- This results in fractions that can be simplified down to their lowest terms.
Additional Conversion Methods
- Converting fractional inches back into decimal form requires dividing the numerator by the denominator (e.g., converting 3/8 inch results in .375).
- To convert from decimal inches to millimeters, multiply by 25.4; for example, .375 inch converts to approximately 9.525 MM.
Visual Representation of Measurement Systems
- A graphical representation illustrates the equivalence between different measurement systems: fractional inches, decimal inches, and metric measurements like millimeters.