Tech Tips Index RASK CYCLE  TECH TIPS

B.S.F SCREW THREADS
Dia of Bolts Threads Per inch Dia. Tap Drill Core Dia   Dia of Bolts Threads Per inch Dia. Tap Drill Core Dia
7/32 28 .1770 .1731   3/4 12 21/32 .6433
1/4 26 .2055 .2007   13/16 12 23/32 .7058
9/32 26 .238 .2320   7/8 11 25/32 .7586
5/16 22 .261 .2543   1 10 57/64 .8719
3/8 20 .316 .3110   1-1/8 9 1 .9827
7/16 18 3/8 .3664   1-1/4 9 1-1/8 1.1077
1/2 16 27/64 .4200   1-3/8 8 1-15/64 1.2149
9/16 16 .492 .4825   1-1/2 8 1.358 1.3399
5/8 14 35/64 .5335   1-5/8 8 1-31/64 1.4649
11/16 14 39/64 .5960    

       

U.N.C Screw Threads

U.N.F. Screw Threads

Dia

(Inch)

 NO. OF Threads Core Dia.

(Inch)

 Tap Drill   Dia

(Inch)

 No. Of Threads Core Dia.

(Inch)

 Tap Drill
1/4 20 .1959 5.2 mm   1/4 28 .2113 5.50 mm
5/16 18 .2524 6.60 mm   5/16 24 .2674 6.90 mm
3/8 16 .3073 8.00 mm   3/8 24 .3299 8.50 mm
7/16 14 .3602 9.40 mm   7/16 20 .3834 9.90 mm
1/2 13 .4167 10.80 mm   1/2 20 .4459 11.50 mm
9/16 12 .4723 12.20 mm   9/16 18 .5024 12.90 mm
5/8 11 .5266 13.50 mm   5/8 18 .5649 14.50 mm
3/4 10 .6417 16.50 mm   3/4 16 .6823 11/16 in.
7/8 9 .7547 49/64 mm   7/8 14 .7977 0.804 in
1 8 .8647 22.25 mm   1 12 .9098 23.25 mm
1-1/3 7 .9704 63/64 in.   1-1/8 12 1.0348 26.50 mm
1-1/4 7 1.0954 1-7/64 in.   1-1/4 12 1.1598 29.50 mm
1-3/8 6 1.1946 1-1364 in.   1-3/8 12 1.2848 1.290 in.
1-1/2 6 1.3196 1-21/64 in.   1-1/2 12 1.4098 36.00 mm
1-3/4 5 1.5335 1.35/64 in.          
2 4-1/2 1.7594 1.25.65 mm