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Workshop reference

UNC and UNF Thread Chart

Common Unified coarse and fine threads with typical tapping-drill references.

ThreadSeriesTPITypical drill
#10-24UNC24No. 25
#10-32UNF32No. 21
1/4-20UNC20No. 7
1/4-28UNF28No. 3
5/16-18UNC18Letter F
5/16-24UNF24Letter I
3/8-16UNC165/16 in
3/8-24UNF24Letter Q
1/2-13UNC1327/64 in
1/2-20UNF2029/64 in

Reference values are general. Confirm the specification, standard and material required for the actual job.