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Centre hole conical depth calculator
This calculator covers the conical section of a centre hole only. Pilot length, protective chamfer and centre-drill catalogue dimensions must be added separately. It does not recommend a numbered centre-drill size.
Formula and inputs
Cone depth = (large diameter − pilot diameter) / (2 tan(included angle / 2)).
Worked example
A 6 mm cone over a 2 mm pilot at a 60° included angle has a 3.464 mm conical section.
Use the result in your setup
Confirm the input dimensions and unit system against your drawing before calculating. Keep full precision during a calculation and round only the final value to suit the measurement or programming requirement. A numerical result does not account for a machine’s complete setup, workholding or control configuration.