Amazon.com: Ruelle Screw Chek'r SAE/ Inch Screw Thread Size Gauge (No. 1 to 5/16) 1/8 Inch Heavy Gauge Steel Screw Checker, Made in USA : Industrial & Scientific
About Machine Screws and Nuts – Sizes and Key Dimensions
Threading Wood for Machine Screws - FineWoodworking
Small Parts 0806FPP Steel Thread Cutting Screw, Zinc Plated Finish, Pan Head, Phillips Drive, Type F, #8-32 Thread Size, 3/8" Length (Pack of 100): Amazon.com: Industrial & Scientific
About Machine Screws and Nuts – Sizes and Key Dimensions
US Machine Screw Sizes
ANSI External Screw Threads Size Tolerances Chart
An easy to read chart of screw sizes and thread counts