TABLE OF CONTENTS 
| Tap Drill Sizes | S = D m - 1.0825 P % (Unified Threads) |
| S = D m - 1.2990 P % (American Standard Threads) | |
| S = D m - 1.0825 P % (ISO Metric Threads) | |
| Percentage of Full Thread | |
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| Determining Machine Screw Sizes | |
| D m = N 0.013 + 0.060 | |
| All dimensions in mm | |
| D m=Major Diameter, P = Pitch, % = Percentage of Full Thread, S = Size of selected Tap Drill, N = Number of Machine Screw | |
| Courtesy of the Society of Manufacturing Engineers |
| Material | Rake Angle, degrees | Speeds ft/min | Lubricant | Comments |
|---|---|---|---|---|
| Alloys, high temperature, nickel or cobalt base nonferrous | 0 10 | 5 10 | Sulfur-chlorinate d mineral lard oil | Nitrided tap or one made from M41, M42, M43, or M44 Steel recommended. Use plug tap having 3-5 chamfered threads. To reduce rubbing of the lands, eccentric or con- eccentric relieved land should be used. To control a continuous chip use a spiral pointed tap for through holes; use low-helix angle spiral fluted taps for blind holes. Oxide coated tap recommended. |
| Aluminum | 8 20 (10 15 recomended) | 90 100 | Heavy duty water soluble oil or light base mineral oil | Spiral pointed... |
