Find the correct tap drill size for threading operations. Includes SAE (inch), metric, and pipe thread sizes with clearance hole recommendations.
Cobalt drill bits for metal and hardened steel. Red Helix flute design clears chips faster. 1/16" to 1/2" in 1/64" increments.
View on AmazonSAE tap and die set with taper, plug, and bottom taps. High carbon steel handles most workshop threading jobs.
View on AmazonCompact brushless drill/driver with 2-speed transmission. 2 batteries included. Perfect for tap drilling operations.
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Thread engagement is the percentage of full thread depth achieved. 75% engagement provides nearly full strength (about 98%) while being much easier to tap than 100%. Going beyond 83% provides minimal strength gain but significantly increases tapping difficulty and tap breakage risk.
UNC (Unified National Coarse) has fewer threads per inch and is standard for general use. UNF (Unified National Fine) has more threads per inch, providing better holding power in thin materials and finer adjustment, but is more susceptible to cross-threading and stripping.
Yes, within reason. A slightly larger drill makes tapping easier but reduces thread engagement. A slightly smaller drill increases engagement but makes tapping harder and increases tap breakage risk. Try to stay within one or two drill number sizes of the recommended size.
For aluminum, you can use the standard 75% tap drill. Aluminum taps easily but tends to gall, so use plenty of cutting fluid. Some machinists prefer going one size larger (reducing to ~65% engagement) to prevent galling and tap binding.