Chapter 10
Give the standard height of dimension text.
.12 inches or 3 mm
What is the recommended length-to-height ratio of arrowheads?
3:1
Describe baseline dimensioning.
A method of dimensioning whereby each feature dimension originates from a common surface, axis or center plane. Each dimension is independent, so there is no tolerance buildup.
Describe Tabular Dimensioning.
A system in which size and location dimensions from datums or coordinates (x, y, and z axes) are given in a table that identifies features on the drawing.
Unilateral Tolerance
A tolerance in which variation is permitted in only one direction from the specified dimension.
Bilateral Tolerance
A tolerance that allows variation in both directions from the design size. (.1000 + .002/-.005).
What is the ASME document that governs the standard for dimensioning and tolerancing?
ASME Y14.5-2009
Identify a possible disadvantage of chain dimensioning.
Caution should be used, as the tolerance of each dimension builds on the next -- known as tolerance buildup or stacking.
Describe a clearance fit.
Clearance between mating parts; largest size of shaft must be smaller than smallest size of hole.
What are the standard units of linear measurements on engineering documents?
Decimal inches
How should decimal in numerals be treated?
Decimals should be clear and bold, and in line with bottom of numerals.
How are notes for holes dimensioned on an engineering document?
Hole sizes are dimensioned with leaders to the view, where they appear as circles, or dimensioned in a sectional view. Leader should center upon beginning (left side) or end (right side) of note.
Describe how holes are located.
Locate a hole center in the view where the hole appears as a circle, or in a sectional view.
Describe Locational fits.
Locational fits are intended to determine only the location of the mating parts, may be rigid or accurate ( as with interference fits), or provide some freedom of location ( as with clearance fits). LC -- clearance fits; LT -- transition fits; LN -- interference fits.
Specified Dimensions
Normal size or part of dimension from which limits are calculated.
Dimension
Numerical value used on a drawing to describe size,shape, location, or machine process
Feature
Physical portion of object -- surface, hole, edge, etc.
Describe running and sliding fits.
RC are intended to provide a similar running performance with suitable lubrication allowances throughout their range of sizes.
List the factors that influence sheet size selection.
The drawing scale to be used, total drawing area, the amount of clear area needed for general notes, and future revisions.
Limits of Dimension
The largest and smallest possible boundaries to which a feature may be made as related to the tolerance of the dimension.
When all dimensions are metric, what is the general note that should accompany the drawing?
UNLESS OTHERWISE SPECIFIED, ALL DIMENSIONS ARE IN MILLIMETERS.
Discuss proper dimension line spacing.
Uniform distance from object ( 3/4" for first dimension, 10 mm minimum), succeeding lines equally spaced (1/2" thereafter 6 mm minimum). Place smallest dimensions closest to object and progressively larger dimensions outward. Group dimensions, and dimensions between views, when possible.
Define least material condition.
When a feature contains the least amount of material; external features at lower limit; internal features at upper limit.
Define maximum material condition.
When a feature contains the most amount of material; external features at upper limit; internal features at lower limit.
Local or specific notes
connected to specific features on vies
Actual size
produced size or part size as measured after production
General notes
separate from views and relate to the entire drawing
Name two classifications of dimensions.
size and location
Tolerance
total permissible variation in size. Difference of the lower from the upper limit.
Should all of the dimension arrowheads on a drawing be the same size?
yes