Holes

2. Holes 3 Basic Types Drilled - Straight Cylinder Counterbore - Two cylinders, one on top of the other. Used to receive a bolt head. Countersink - A cone on top of a cylinder. Used to accept a flat head bolt/screw.

3. Hole Types Hole Counterbore - receives a bolt head Countersink - receives a flat head screw or bolt

4. Hole Feature Placement • A hole feature requires a hole center point sketched on an existing feature. You can also select endpoints or center points on existing geometry as hole centers.

5. Threaded Holes • Threads can be added to holes for bolts or screws. There are several types of threads series. Each is identified by their: • Major Diameter • Threads Per Inch • Thread Series Identification • Ex. 9/16 - 12 UNC • This represents a thread with a major diameter of 9/16”, 12 threads per inch and is a standard Unified National Course thread.

6. Thread Patterns • UNF - Unified National File • UNC - Unified National Course • UNS - Unified National Special • UNEF - Unified National Extra Fine • ISO - International Standards • UN - American National (External Thread) • UNR - American National (Internal Thread)

7. Pitch Depth Rounded Root Unified National Thread Form

8. Pitch Depth Flat Root American National Thread Very similar to Unified National Threads but has a Flat Root.

9. Pitch Depth Flat Root Metric Thread Forms - ISO

10. Unified And American Threads .5 - 13 UNC - 2A _ .75 Blank=Right hand, LH=Left Hand A=External, B=Internal • Class of Fit • 1=large tolerance , 2=General purpose, 3=low tolerance Thread Series - UNF, UNC, UN, UNR # of Threads per Inch Major Diameter Thread Annotations Thread Depth - Internal

11. Thread Annotations ISO Thread Forms M12 X 1.5--6H • # Between 3 & 9 identifies grade of tolerance • 3 - 5 Fine, 6 is most common, 7-9 Course • Letter Denotes Thread Tolerance H=low, G=tight • H or G for Internal, g or h for External Thread Pitch in millimeters followed by a dash X means by Nominal Major Diameter in millimeters Designates Metric