10 x .75 metric tap drill chart iso#

I'll use a #10-32 Unified screwthread for a worked example: they both have a 60 degree flank angle, a 1/8 Pitch flat at the Major Diameter, and a 1/4 Pitch flat at the Minor Diameter.)

10 x .75 metric tap drill chart iso#

(Remember that the basic forms of the Unified and ISO Metric screwthreads are IDENTICAL. Either metric or imperial units may be used, but the same unit must be used for both Major Diameter and Pitch.Ī corresponding rule of thumb to calculate the diameter of a hole to be single-start threaded with a Unified or ISO Metric threadform forming tap is 'Nominal Major Diameter minus the Single Depth of Thread', which is itself calculated from the basic threadform as '5/8 Pitch times Cosine 30 degrees'. All rights reserved.This evening's sermon is given from high atop one of my very favorite soapboxes - that understanding the fundamental geometry of the two most common threadforms, the Unified and ISO Metric threadforms, enables we of the proletariat to calculate thread-chart values for ourselves, in the absence sufficient reference material, without resort to memorized 'magic numbers':Īs Forrest Addy describes, the rule of thumb to calculate the diameter of a hole to be threaded by material-removing methods (a cutting tap, single-pointing, or milling) for single-start US Standard, Unified, and ISO Metric threadforms is 'Nominal Major Diameter minus Pitch'. One pitch length from the major diameter.įormula: Major Dia.

In general, you can find the tap-drill for any size 60 degree thread, subtract

METRIC FINE SIZES - TAP DRILL SIZE SIZE - 4 mm x. 75% thread) METRIC COARSE SIZES - TAP DRILL SIZE SIZE - 1mm x. Steam, Oilfield, and Gas Engine Restoration