Prufi
PRU-143Declared input

Blind tap full thread and lead clearance

Machining

Scope and limits

Selected simple flat-bottom blind bore cylindrical depth against explicit full-thread depth plus selected tap physical lead and qualified bottom clearance in mm. No thread or engagement strength inferred. Explicit operation-compatible precursor geometry_state required (pre_tapping); omitted or finished_part is unassessed.

Standards and references

GUHRING-TAP-CHAMFER:web-2026-10-03

Gühring tap chamfer forms and blind-hole clearance

Source scope
Tap chamfer depends on the selected tool, material and blind/through application. Form C is 2–3 threads and Form E 1.5–2 threads, not a universal minimum thread engagement.
Implementation in Prufi
PRU-143 checks a selected simple flat-bottom blind bore. Explicit full_thread_depth_mm excludes incomplete threads; tap_lead_mm is the actual axial distance from the physical tap tip to the first full thread, including any extra nose. bottom_clearance_mm is a qualified additional margin. Sum must not exceed cylindrical depth. No pitch inference, thread annotation inference or thread strength assessment; conical floors, steps and through holes receive INFO. Explicit geometry_state=pre_tapping requires actual drilled precursor CAD; omitted or finished_part remains unassessed rather than inferring drilled depth from final threads.

STEP examples for this check

No public STEP example is currently assigned to this check.

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