Tap Drill, Thread & Fastener Calculators

Holes and threads are on almost every part, and they cause more scrap than they should. A tap breaks in a blind hole. A thread gauge will not go. A bolt head does not sit flush in its counterbore. The tools in this hub help you get these small features right before the part goes on the machine.

Start with the tap drill calculator. It gives the drill size for a chosen percentage of thread engagement in inch and metric threads. Then use the blind hole tap depth checker to make sure there is room below the tap for its lead and the chips. The thread edge margin tool warns you when a tapped hole sits too close to an edge.

To cut threads, use the helical thread milling generator on a CNC mill or the pass calculator for single-point threading on a lathe. To check a thread, the three-wire calculator gives the best wire size and the measurement over wires.

For holes, work out drill point depth, reamer stock allowance and countersink depth. The hole L:D tool flags deep holes that need peck drilling or a better drill. On the assembly side, look up clearance holes, bolt torque and preload, press fit force and shrink fit temperature.

The reference charts cover tap drills, socket head cap screws, countersunk bolts, pop rivets and wrench sizes. Always check the result against your drawing and the thread standard it calls for.