HeliCoil / Thread Insert Calculator
Estimate drill size and STI tap direction for common metric coil-thread inserts. Supplier charts differ; verify the insert brand and standard before production.
✓ Runs in your browser↔ Metric and inch unitsƒ Formula shown
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Enter machining data
Default values are examples. Replace them with your actual setup data.
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Formula and engineering notes
Formula / logic
Lookup-style estimate for common metric coil-thread inserts using STI taps. Drill sizes vary by supplier; this build uses common chart values such as M6×1.0 → 6.2 mm and M10×1.5 → 10.3 mm.
Lookup-style estimate for common metric coil-thread inserts using STI taps. Drill sizes vary by supplier; this build uses common chart values such as M6×1.0 → 6.2 mm and M10×1.5 → 10.3 mm.
Engineering disclaimer: these tools are for estimating and planning. Verify production parameters with toolmaker catalogs, machine limits, material data, and applicable standards.
Frequently asked questions
Can this result be used directly on a CNC machine?
Use it as a starting value only. Check the tool manufacturer data, machine limits, workholding, coolant and material condition before production.
Which units does the calculator support?
The calculator shows the units beside each input. Select metric or inch units where the page provides a unit-system control.
Why can shop results differ from the calculation?
Tool geometry, coating, runout, rigidity, chip evacuation, material hardness and machine power can change the practical result.