Technical resources
Thread charts, grade markings and other reference guides.
Inch thread and tap drill chart
UNC (USS/Coarse) and UNF (SAE/Fine) threads per inch and tap drills.
Metric thread and tap drill chart
Coarse, fine, extra fine and ultra fine pitches by diameter.
Bolt grade markings
How to identify SAE, metric and stainless bolt and nut grades.
Pipe thread (NPT) chart
Threads per inch, outside diameter and tap drill for NPT pipe sizes.
Abrasive grit chart
Which grit to use, from heavy stock removal to finishing.