| *DRILL SIZES FOR Free Cutting Metals Steel, Aluminum Copper and Copper Alloys | |
|---|---|
| Drill Size | Decimal |
| 56 | .0465 |
| 53 | .0595 |
| 53 | .0595 |
| 51 | .0670 |
| 50 | .0700 |
| 48 | .0760 |
| 48 | .0760 |
| 44 | .0860 |
| 43 | .0890 |
| 39 | .0995 |
| 38 | .1015 |
| 36 | .1065 |
| 33 | .1130 |
| 29 | .1360 |
| 29 | .1360 |
| 26 | .1470 |
| 5/32 | .1562 |
| 11/64 | .1719 |
| 15 | .1800 |
| 8 | .1990 |
| 3 | .2130 |
| F | .2570 |
| I | .2720 |
| 5/16 | .3125 |
| Q | .3320 |
| W | .3860 |
| 27/64 | .4219 |
| 31/64 | .4844 |
| 1/2 | .5000 |
| 17/32 | .5312 |
| 9/16 | .5625 |
| 21/32 | .6562 |
| 11/16 | .6875 |
| 49/64 | .7656 |
| 51/64 | .7969 |
| 7/8 | .8750 |
| 59/64 | .9219 |
|
*Drill sizes recommended for “Free Cutting Materials” produces 65-75% of thread. **For “Hard or Rough Materials”, 60-70% of thread. |
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TAPPING TIPS Strength of tapped holes: Strength tests show that any increase over 60% of thread for the tapped holes does not increase static strength of fastening. Bolts break at 55% of engagement. Tapping blind holes: Drill hole deep enough to accommodate chips. Tap breakage: If difficulty or breakage occurs, check drill size in view of material hardness and make sure tap is sharp. Breaking small drills: Small drills (1/8″ and under) break easily when they are not run at high speeds. Difficulty in drilling: If starting drill is difficult, thinning web of drill at the point solves this problem. Class of fit: Most commercial bolts and screws are made to fit 2A external thread standards, which fit with 2B tapped threads. |
|
| Tap Size | ||
|---|---|---|
| Diameter | Threads Per Inch | |
| UNC | UNF | |
| 0 | 80 | |
| 1 | 64 | |
| 72 | ||
| 2 | 56 | |
| 64 | ||
| 3 | 48 | |
| 46 | ||
| 4 | 40 | |
| 48 | ||
| 5 | 40 | |
| 44 | ||
| 6 | 32 | |
| 40 | ||
| 8 | 32 | |
| 36 | ||
| 10 | 24 | |
| 32 | ||
| 12 | 24 | |
| 28 | ||
| 1/4 | 20 | |
| 28 | ||
| 5/16 | 18 | |
| 24 | ||
| 3/8 | 16 | |
| 24 | ||
| 7/16 | 14 | |
| 20 | ||
| 1/2 | 13 | |
| 20 | ||
| 9/16 | 12 | |
| 18 | ||
| 5/8 | 11 | |
| 18 | ||
| 3/4 | 10 | |
| 16 | ||
| 7/8 | 9 | |
| 14 | ||
| 1 | 8 | |
| 12 | ||
|
*Drill sizes recommended for “Free Cutting Materials” produces 65-75% of thread. **For “Hard or Rough Materials”, 60-70% of thread. |
||
|
TAPPING TIPS Strength of tapped holes: Strength tests show that any increase over 60% of thread for the tapped holes does not increase static strength of fastening. Bolts break at 55% of engagement. Tapping blind holes: Drill hole deep enough to accommodate chips. Tap breakage: If difficulty or breakage occurs, check drill size in view of material hardness and make sure tap is sharp. Breaking small drills: Small drills (1/8″ and under) break easily when they are not run at high speeds. Difficulty in drilling: If starting drill is difficult, thinning web of drill at the point solves this problem. Class of fit: Most commercial bolts and screws are made to fit 2A external thread standards, which fit with 2B tapped threads. |
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| **DRILL SIZES FOR Hard or Tough Metals Carbon & Alloy Steel, Heat Treated Steels, Stnls Steels |
|
|---|---|
| Drill Size | Decimal |
| 3/64 | .0469 |
| 53 | .0595 |
| 53 | .0595 |
| 50 | .0700 |
| 49 | .0730 |
| 46 | .0810 |
| 45 | .0820 |
| 43 | .0890 |
| 42 | .0935 |
| 38 | .1015 |
| 37 | .1040 |
| 7/64 | .1094 |
| 32 | .1160 |
| 29 | .1360 |
| 28 | .1405 |
| 24 | .1520 |
| 21 | .1590 |
| 16 | .1770 |
| 14 | .1820 |
| 6 | .2040 |
| 7/32 | .2188 |
| 14/64 | .2656 |
| J | .2770 |
| P | .3230 |
| R | .3390 |
| 3/8 | .3750 |
| 25/64 | .3906 |
| 7/16 | .4375 |
| 29/64 | .4531 |
| 1/2 | .5000 |
| 33/64 | .5156 |
| 35/64 | .5469 |
| 37/64 | .5781 |
| 43/64 | .6719 |
| 45/364 | .7031 |
| 25/32 | .7812 |
| 13/16 | .8125 |
| 57/64 | .8906 |
| 15/16 | .9375 |
|
*Drill sizes recommended for “Free Cutting Materials” produces 65-75% of thread. **For “Hard or Rough Materials”, 60-70% of thread. |
|
|
TAPPING TIPS Strength of tapped holes: Strength tests show that any increase over 60% of thread for the tapped holes does not increase static strength of fastening. Bolts break at 55% of engagement. Tapping blind holes: Drill hole deep enough to accommodate chips. Tap breakage: If difficulty or breakage occurs, check drill size in view of material hardness and make sure tap is sharp. Breaking small drills: Small drills (1/8″ and under) break easily when they are not run at high speeds. Difficulty in drilling: If starting drill is difficult, thinning web of drill at the point solves this problem. Class of fit: Most commercial bolts and screws are made to fit 2A external thread standards, which fit with 2B tapped threads. |
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