1. Features… Learning to read the information
Every drawing should include all the information… however, it is not always clear unless you know what you are seeing.
L. Tatro CHSE 2011

2. Objectives Students should be able to…
Understand the different meanings of commonly used symbols used in drafting.
Relate terms to the appropriate features.
Visually identify different features and understand how they are displayed in drafting.

3. Reading the numbers… Understanding the symbols…
Often times symbols are used to help explain what we are seeing in the drawings. Universal symbols are used so every person reading the drawings can understand them…
If they know the meaning of each symbol used.
L. Tatro CHSE 2011

4. Symbols…
#X: This means that this applies throughout the drawing ___# of times.
n This means diameter
q This means centerline
v This means Counterbore (a square cut oversized hole symmetrically around a smaller through hole
x This means depth. This will be given when a hole, or counterbore does not go through the entire part.
w This means countersink. When a hole has an interior chamfer this symbol is used.
8 2O Along with a countersink
symbol, a degree value is
given for the tapered angle.
When seeing a set of numbers
stacked, this is used to give a
acceptable range (tolerance).
L. Tatro CHSE 2011

5. Continued R This means radius
TYP This means typical and is used when a drawing has a situation that repeats itself and is constant.
EQL SP Used when the distance between hole or features have a repeating value. Typically used in polar dimensioning .
BC means bolt circle and is used when a circular centerline is used to make the center locations of a bolt pattern.
L. Tatro CHSE 2011

6. Understanding the terms..
From Page 134 from your text
Understanding the terms..
This segment will help you identify and understand many of the terms used in the drafting/machining industry for specific features.

7. Fillet: A rounded interior blend between surfaces.
Round: A rounded exterior blend between surfaces.
Counterbore: A cylindrical recess around a hole, usually to receive a bolt head or nut.

8. Countersink: A conical shaped recess around a hole, usually to receive a tapered screw head.
Spotface: A shallow recess like a counterbore, used to provide a good bearing surface for a fastener.
Boss: A short raised protrusion above the surface of a part, often used to provide a strong flat bearing surface.
Boss

9. Lug: A flat or round tab protruding from a surface usually to provide a method for attachment.
Flange: A flattened collar or rim around a cylindrical part to allow for attachment.
Chamfer: An angled surface, used on cylinders to make them easier to start.
Flange

10. Neck: A small groove cut around the diameter of a cylinder or hub to receive a key, used to attach hubs, gears, and other parts to a cylinder so they won’t turn on it
Neck
Keyway : A shaped depression cut along the axis of a cylinder to receive a key (When mating two parts to prevent rotation).
Keyway
alouline.info

11. Knurl: A pattern form on a surface to provide for better gripping or more surface area for attachment, often used on knobs and tool handles.
Rib: Like a boss, a rib is used internally to add strength to, or between features.
Bushing: A hollow cylinder that is often used as a protective sleeve or guide, or as a bearing.
RIB

12. Self Quiz…. Left click to see the feature name in order1 2 3 4 5 7 6 8 9 10 11 12 13

13. Understanding Lines and their meaning

16. SECTION/HATCH LINES CUTTING PLANE LINE CENTER MARK BORDER LINE
DEGREES AND EVENLY SPACED
CUTTING PLANE LINE
MED-DRK AND THICK
CENTER MARK
MED AND THIN
BORDER LINE
DRK AND THICK
OBJECT OR VISIBLE
DRK AND THICK
CENTER LINE
MED & THIN
EXTENSION
MED AND THIN
DIMENSION LINE
MED & THIN
CONSTRUCTION LINE
LIGHT AND THIN
TITLE BLK/BORDER LINE
DRK AND THICK