Interpreting Blueprints 230

This class provides an overview of common features found in prints and describes how to properly inspect them. Includes an Interactive Lab.

Class Details

Class Name:
Interpreting Blueprints 230
Number of Lessons:
Additional Language:
Spanish, Chinese

Class Outline

  • Objectives
  • The Importance of Reading Prints
  • The Sample Print
  • Common Shop Terminology
  • Angles, Chamfers, and Tapers
  • Sample Print: Angled Features
  • Common Hole Features
  • Sample Print: Hole Dimensions
  • Corner Radii and Arcs
  • Sample Print: Radius Dimension
  • Surface Finish
  • Sample Print: Surface Finish
  • Threads
  • Thread Standards
  • Sample Print: OD Thread
  • Summary


  • Describe the relationship between prints and inspection.
  • Identify information in a print relating to a section view.
  • Identify shop terminology that commonly appears in prints.
  • Identify information in a print that specifies angled features.
  • Describe proper methods for checking an angled feature on a part.
  • Identify common types of hole features.
  • Describe proper methods for checking a hole on a part.
  • Identify information in a print that specifies a feature with a radius.
  • Describe proper methods for checking a corner radius on a part.
  • Describe how surface finish is specified in a common print.
  • Describe proper methods for checking surface finish on a part.
  • Identify common methods for specifying a thread in a print.
  • Describe a thread based on its standard specification.
  • Describe proper methods for checking an OD thread on a part.

Job Roles


  • Metalforming I
  • MSSC Fast Track Quality
  • MSSC Quality Practices and Measurement


Vocabulary Term Definition
arc A curved feature representing a portion of a circle.
auxiliary view A view drawn at a right angle to an angled feature of the part. Auxiliary views show the true size of an angled surface.
blind hole A hole that is closed at its bottom.
blueprint A document containing all the instructions necessary to manufacture and inspect a part. The key sections of a blueprint are the drawing, dimensions, and notes.
bolt hole pattern A number of holes with centers that are positioned around the circumference of an imaginary circle.
bore gage A hole inspection gage that makes three points of contact within the hole. Bore gages are handheld, variable instruments that provide very accurate readings of hole sizes.
boss A raised, circular peg or protrusion. A boss often has a hole in the center and is used to improve assembly.
burr A rough, sharp edge remaining on a part after machining or stamping. Burrs pose an injury risk and interfere with the fitting of parts.
casting A part formed by pouring molten metal into a mold until it cools and solidifies into its final shape. Castings tend to have rougher surface textures.
center For circles and arcs, it is the point that is equally distant from all other points located on the circle's circumference or the arc.
center line A line used to define the center of a hole, a cylindrical part, or symmetrical part. Center lines consist of alternating long and short dashes.
chamfer A small, angled surface added on the end of a shaft, around the opening of a hole, or along an edge. A chamfer removes the sharp edge and helps remove burrs.
corner radius A rounded internal corner located where two features meet on either a flat or cylindrical part.
counterbore A larger diameter added at a hole opening, with a flat surface between the two diameters. A counterbore provides a space for the head of a bolt or other type of fastener.
countersink An enlarged, angled surface added to a hole opening. A countersink differs from a counterbore because it leaves a tapered opening.
deburring The removal of burrs on a part by processes such as grinding or filing.
degrees A common unit of measurement used to indicate the size of an angle.
diameter The distance from one edge of a circle to the opposite edge that passes through the center. Round or cylindrical features require diameter measurements.
fillet A rounded internal corner. A fillet adds strength to the corner and is often easier to machine.
go gage A gage on or in which a good part should fit easily.
hidden line A line used to define a part feature that is not visible in a specific view. Hidden lines consist of a series of short dashes.
ID thread A thread located on the interior surface of a cylindrical hole.
knurl A patterned series of grooves or diamond-shaped marks formed into the part surface. A knurl is added to provide a surface for gripping.
machining The process of removing metal to form or finish a part, either with traditional methods like turning, drilling, milling, and grinding, or with less traditional methods that use electricity, heat, or chemical reaction.
microinches One-millionth (.000001) of the U.S. standard inch. Surface roughness is typically measured in microinches.
neck A groove or smaller-diameter section between two larger diameters on a cylindrical part. A neck allows a flush or tight fit between the largest diameter and another part.
no-go gage A gage on or in which a good part should not fit.
nose radius The rounded tip on the cutting edge of a single-point tool. The nose radius on a tool leaves a matching corner radius on a part.
OD thread A thread located on the exterior surface of a cylindrical part or feature.
optical comparator An inspection instrument that projects a magnified shadow of a part feature onto a screen for measurement.
pictorial method A blueprint method of specifying a thread by attempting to represent the actual two-dimensional appearance of the thread.
pin gage A hardened, cylindrical gage used to inspect the size of a hole. Pin gages are available in standard diameters.
pocket An enclosed recess, often in a rectangular part. Most pockets are square or rectangular with rounded corners.
profilometer An inspection device that uses a stylus to trace along the surface of a part and determine its average roughness.
radius The distance from the center to the edge of a circle or arc. The size of a radius determines the size of the circle or arc.
radius gage A handheld gage with an accurate, rounded corner used to inspect the size of a corner radius on a part. Radius gages are available in a set that offers a range of sizes.
roughness The inherent, fine, closely spaced irregularities remaining on a part surface after manufacturing.
schematic method A blueprint method of specifying a thread by showing a series of parallel lines.
section line A line used to identify the imaginary cut portion of a part in a section view. Section lines appear as a series of diagonal lines drawn close together.
section view A view illustrating a rotated section resulting from an imaginary cut in the part. Blueprints may contain a variety of different section views.
simplified method A blueprint method of specifying a thread by including pairs of solid and dashed lines drawn parallel to the thread. The simplified method is the most common method for specifying a thread.
spotface A shallow, larger diameter added at the top of a hole. A spotface is most often used on castings to provide a flat surface for assembly.
stylus A small, cone-shaped spherical point made of diamond that contacts the part and measures surface roughness.
surface finish The degree of smoothness of a part's surface after it has been manufactured. Surface finish is the result of the surface roughness, waviness, and flaws remaining on the part.
taper For a cylindrical part, it is a gradual decrease in diameter from one end to another. For a flat or rectangular part, it is an angled surface that gradually changes from a larger height to a smaller height at a constant slope or incline.
thread A raised, helical rib or ridge around the interior or exterior of a cylindrically shaped object. Threads are found on screws, nuts, and bolts and are used to fit parts or provide motion.
thread class A number and letter combination that indicates the degree of fit for a thread.
thread form The specific shape or profile of a thread. Thread forms include V-shaped or square threads.
thread ring gage A disk of heavy metal with a central, threaded hole made to match a particular OD thread. The gage is screwed onto the part being inspected as though the two are mating parts.
thread series A thread designation that identifies the coarseness or fineness of a thread.
THRU A hole that passes completely through a part's material.
Unified thread system A standard thread form based on inches that was developed by the U.S., Canada, and Great Britain.