An offline tap drill and clearance drill chart for metric, UNC and UNF threads, with a thread-depth calculator, pipe thread charts and the full drill index. No account, no network.
Where do the tap drill sizes come from?
They are the published sizes from the standard tables — ISO 261/262 for metric coarse and fine, and the Unified series for UNC and UNF. They are not calculated and rounded, so they match the chart on your workshop wall rather than disagreeing with it by a hundredth.
What percentage of thread do the chart's drills give?
About 75%, which is what almost every job wants: thread strength is nearly all won by then, and going deeper multiplies tapping torque for very little gain. The Bench tab works out the drill for any depth from 50% to 100% if you need a different one.
Why do some rows show no clearance drill?
Because the published close-fit clearance tables for numbered machine screws vary between sources. Rather than print a number we cannot stand behind, the row simply leaves it out. Metric clearances follow ISO 273 and imperial fractional clearances follow the standard close-fit series.
Can I search in whichever system I have?
Yes. Type the thread the way you say it — M6, m6x1, 1/4, 1/4-20, 10-24, #10 — and the chart finds it. Every size is shown in millimetres, and imperial rows also name the fraction, number or letter stamped on the drill.
What does the purchase add, and is the chart affected?
The chart is free and always will be. The one-time purchase unlocks the Bench tab: a thread-depth calculator in both directions, the NPT, BSPT and BSPP pipe thread charts, and the complete drill index across fraction, number, letter and metric sizes.
Does it work with no signal?
Entirely. Everything is in the app. Nothing is fetched and nothing is stored anywhere but your phone.
Email quicksupport36@gmail.com and describe what happened. Including your device model and iOS version helps.
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