Helicoil Drill Chart

The minimum drilling depths shown below allow for the following recommended practices:

Countersinking the drilled hole to prevent a feather edge at the start of the tapped hole. 3/4 - 1-1/2 pitch of insert "set down" to allow for maximum production tolerance. Dimensions are shown for both plug and bottoming taps.

Helicoil Drilling Data - Metric   For plug Taps 5/16" or M8 and smaller. F is equal to the insert nominal length (Q) + ½ the nominal bolt diameter + 5 Pitch (allowing for tap chamfer, countersink and maximum “set-down”). For Plug Taps 3/8" or M10 and larger F is equal to the insert nominal length (Q) + 5 Pitch (allowing for tap chamfer, counter sink and maximum “set-down”). For bottoming Taps. F is equal to the insert nominal length (Q) + 3 Pitch (allowing for tap chamfer, countersink and maximum “set-down”).