BoltLab

Tapping & Threading Atlas

Explore BoltLab's structured tapping and thread-preparation data for metric, UNC, and UNF threads. Search by thread designation, filter the available records, and review tap-drill recommendations, ISO 2306 alternatives, tap types, standards, and data-quality status.

Data quality

  • Dataset: Tapping & Threading
  • Projection: T3 Tapping Projection
  • Thread systems: Metric, UNC, UNF
  • Records: 29 tapping profiles
  • Tap types: 7
  • Tap-drill values: 9 verified / 20 source-bound
  • ISO 2306 alternatives: 15 verified
  • Axial engagement: Not currently calculable
  • Last reviewed: 2026-08-15
  • Verification: Mixed — see record-level status
  • Sources: ASME, ISO

How BoltLab classifies and verifies engineering data

Search and filters

Results

Showing 29 of 29 tapping profiles.

M10x1.25

Metric · 10 mm · 1.25 mm · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 8.8 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M10x1.25
  • Source field: tap_drill_mm
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

M10x1.5

Metric · 10 mm · 1.5 mm · coarse

Tap drill: Verified

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 8.5 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M10x1.5
  • Source field: tap_drill_mm
  • Verification status: Verified
  • Cross-check: Matches Table 1 (coarse pitch series) exactly (verified 2026-08-15)
  • Last reviewed: 2026-08-15

M12x1.25

Metric · 12 mm · 1.25 mm · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 10.8 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M12x1.25
  • Source field: tap_drill_mm
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

M12x1.75

Metric · 12 mm · 1.75 mm · coarse

Tap drill: Verified

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 10.2 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M12x1.75
  • Source field: tap_drill_mm
  • Verification status: Verified
  • Cross-check: Matches Table 1 (coarse pitch series) exactly (verified 2026-08-15)
  • Last reviewed: 2026-08-15

M16x1.5

Metric · 16 mm · 1.5 mm · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 14.5 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M16x1.5
  • Source field: tap_drill_mm
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

M16x2.0

Metric · 16 mm · 2 mm · coarse

Tap drill: Verified

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 14 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M16x2.0
  • Source field: tap_drill_mm
  • Verification status: Verified
  • Cross-check: Matches Table 1 (coarse pitch series) exactly (verified 2026-08-15)
  • Last reviewed: 2026-08-15

M20x2.0

Metric · 20 mm · 2 mm · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 18 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M20x2.0
  • Source field: tap_drill_mm
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

M20x2.5

Metric · 20 mm · 2.5 mm · coarse

Tap drill: Verified

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 17.5 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M20x2.5
  • Source field: tap_drill_mm
  • Verification status: Verified
  • Cross-check: Matches Table 1 (coarse pitch series) exactly (verified 2026-08-15)
  • Last reviewed: 2026-08-15

M3x0.5

Metric · 3 mm · 0.5 mm · coarse

Tap drill: Verified

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 2.5 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M3x0.5
  • Source field: tap_drill_mm
  • Verification status: Verified
  • Cross-check: Matches Table 1 (coarse pitch series) exactly (verified 2026-08-15)
  • Last reviewed: 2026-08-15

M4x0.7

Metric · 4 mm · 0.7 mm · coarse

Tap drill: Verified

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 3.3 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M4x0.7
  • Source field: tap_drill_mm
  • Verification status: Verified
  • Cross-check: Matches Table 1 (coarse pitch series) exactly (verified 2026-08-15)
  • Last reviewed: 2026-08-15

M5x0.8

Metric · 5 mm · 0.8 mm · coarse

Tap drill: Verified

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 4.2 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M5x0.8
  • Source field: tap_drill_mm
  • Verification status: Verified
  • Cross-check: Matches Table 1 (coarse pitch series) exactly (verified 2026-08-15)
  • Last reviewed: 2026-08-15

M6x1

Metric · 6 mm · 1 mm · coarse

Tap drill: Verified

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 5 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M6x1
  • Source field: tap_drill_mm
  • Verification status: Verified
  • Cross-check: Matches Table 1 (coarse pitch series) exactly (verified 2026-08-15)
  • Last reviewed: 2026-08-15

M8x1.0

Metric · 8 mm · 1 mm · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 7 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M8x1.0
  • Source field: tap_drill_mm
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

M8x1.25

Metric · 8 mm · 1.25 mm · coarse

Tap drill: Verified

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 6.8 mm
Metric drill convention

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ISO 2306, ISO 261, ISO 262, ISO 724, ISO 965-1

Data provenance
  • Source dataset: metric_threads
  • Source record: M8x1.25
  • Source field: tap_drill_mm
  • Verification status: Verified
  • Cross-check: Matches Table 1 (coarse pitch series) exactly (verified 2026-08-15)
  • Last reviewed: 2026-08-15

#10-24 UNC

UNC · 0.19 in · 24 TPI · coarse

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.1495 in
US customary drill convention

ISO 2306 alternative: 3.9 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unc_threads
  • Source record: #10-24 UNC
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

1/2-13 UNC

UNC · 0.5 in · 13 TPI · coarse

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.4219 in
US customary drill convention

ISO 2306 alternative: 10.8 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unc_threads
  • Source record: 1/2-13 UNC
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

1/4-20 UNC

UNC · 0.25 in · 20 TPI · coarse

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.201 in
US customary drill convention

ISO 2306 alternative: 5.1 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unc_threads
  • Source record: 1/4-20 UNC
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

3/8-16 UNC

UNC · 0.375 in · 16 TPI · coarse

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.3125 in
US customary drill convention

ISO 2306 alternative: 8 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unc_threads
  • Source record: 3/8-16 UNC
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

#4-40 UNC

UNC · 0.112 in · 40 TPI · coarse

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.089 in
US customary drill convention

ISO 2306 alternative: 2.35 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unc_threads
  • Source record: #4-40 UNC
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

5/16-18 UNC

UNC · 0.313 in · 18 TPI · coarse

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.257 in
US customary drill convention

ISO 2306 alternative: 6.6 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unc_threads
  • Source record: 5/16-18 UNC
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

#6-32 UNC

UNC · 0.138 in · 32 TPI · coarse

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.1065 in
US customary drill convention

ISO 2306 alternative: 2.85 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unc_threads
  • Source record: #6-32 UNC
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

#8-32 UNC

UNC · 0.164 in · 32 TPI · coarse

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.136 in
US customary drill convention

ISO 2306 alternative: 3.5 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unc_threads
  • Source record: #8-32 UNC
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

#10-32 UNF

UNF · 0.19 in · 32 TPI · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.159 in
US customary drill convention

ISO 2306 alternative: 4.1 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unf_threads
  • Source record: #10-32 UNF
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

1/2-20 UNF

UNF · 0.5 in · 20 TPI · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.4531 in
US customary drill convention

ISO 2306 alternative: 11.5 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unf_threads
  • Source record: 1/2-20 UNF
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

1/4-28 UNF

UNF · 0.25 in · 28 TPI · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.213 in
US customary drill convention

ISO 2306 alternative: 5.5 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unf_threads
  • Source record: 1/4-28 UNF
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

3/8-24 UNF

UNF · 0.375 in · 24 TPI · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.332 in
US customary drill convention

ISO 2306 alternative: 8.5 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unf_threads
  • Source record: 3/8-24 UNF
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

5/16-24 UNF

UNF · 0.313 in · 24 TPI · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.272 in
US customary drill convention

ISO 2306 alternative: 6.9 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unf_threads
  • Source record: 5/16-24 UNF
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

#6-40 UNF

UNF · 0.138 in · 40 TPI · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.113 in
US customary drill convention

ISO 2306 alternative: 2.95 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unf_threads
  • Source record: #6-40 UNF
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

#8-36 UNF

UNF · 0.164 in · 36 TPI · fine

Tap drill: Source-bound

Overall record status: Source-bound (engagement and process-parameter data are not yet available for any profile)

Primary tap drill: 0.136 in
US customary drill convention

ISO 2306 alternative: 3.5 mm · Verified

ISO 2306 provides a metric drill recommendation for these inch-thread records. It is shown separately from BoltLab's primary US-customary drill value and does not replace it.

Tap types: Bottoming Tap, Plug Tap, Spiral Flute Tap, Spiral Point Tap, Taper Tap

Standards: ASME B1.1, ISO 2306

Data provenance
  • Source dataset: unf_threads
  • Source record: #8-36 UNF
  • Source field: tap_drill_in
  • Verification status: Source-bound
  • Last reviewed: 2026-08-15

Tap types

Structural, sourced application knowledge for the seven tap types in BoltLab's tapping domain. Facts are labeled by evidence kind — general taxonomy, manufacturing characteristic, typical application, or manufacturer-specific recommendation — and by verification status.

Taper Tap

A tap with a gradually tapered chamfer at the point, typically engaging six to eight threads before reaching full thread form, used to start threads gradually and reduce cutting force per pass.

Manufacturing characteristics

  • Chamfer length is approximately 7-10 threads/pitches, the longest of the three chamfer-length tap styles. (Source-bound)

Typical applications

  • Long chamfer distributes cutting load gradually and makes the tap easier to start straight/square, but it cannot cut full-depth threads within roughly 7-10 pitches of the bottom of a blind hole. (Source-bound)

Plug Tap

A tap with a moderate chamfer length, shorter than a taper tap but longer than a bottoming tap, engaging approximately three to five threads before reaching full thread form.

Manufacturing characteristics

  • Chamfer length is approximately 3-5 threads/pitches, shorter than a taper tap and longer than a bottoming tap. (Source-bound)

Typical applications

  • General-purpose tap; commonly the sole tap used for through-hole tapping, and can start in an unthreaded hole (unlike a bottoming tap). (Source-bound)

Bottoming Tap

A tap with a short chamfer, typically engaging one to one and a half threads before reaching full thread form, designed to cut threads as close as practical to the bottom of a blind hole.

General taxonomy

  • Incomplete internal threads are inherently present at the bottom of a tapped blind hole -- the physical reason bottoming taps exist as a distinct style. (Verified)

Manufacturing characteristics

  • Chamfer length is approximately 1-2 threads/pitches, the shortest of the three chamfer-length tap styles. (Source-bound)

Typical applications

  • Cannot start in an unthreaded hole; used to extend threads to the base of a blind hole after a taper and/or plug tap has already established the thread. (Source-bound)

Spiral Point Tap

A tap with an angled point ground onto the flutes that pushes chips forward, ahead of the tap and out through the far side of the hole, commonly associated with through-hole applications.

Manufacturing characteristics

  • Also called a gun tap or gun-nose tap; a forward-angled point ground onto the cutting chamfer drives chips forward, ahead of the tap. (Source-bound)

Typical applications

  • Suited to through-hole tapping only. In a blind hole the forward-pushed chips have nowhere to go, pack at the bottom, and can bind and break the tap. (Source-bound)

Spiral Flute Tap

A tap with helical (spiral) flutes that lift chips backward out of the hole entrance during cutting, commonly associated with blind-hole applications.

Manufacturing characteristics

  • Helical (spiral) flutes lift chips backward, up and out of the hole entrance, opposite in direction to a spiral-point tap. (Source-bound)

Typical applications

  • Suited to blind-hole tapping, where chips cannot be pushed forward out of a closed bottom. (Source-bound)

Forming Tap

A tap that forms threads by radially displacing material rather than cutting it, producing no chips; also referred to as a roll tap or fluteless tap.

Manufacturing characteristics

  • Requires a larger pre-tap hole diameter than an equivalent cutting tap, since material is displaced outward rather than removed. (Source-bound)

Typical applications

  • Unsuitable for brittle materials such as cast iron, which can crack rather than flow under the forming pressure. (Source-bound)
  • Produces no chips, which removes chip-evacuation as a constraint on blind-hole use -- unlike cutting taps, hole geometry (blind vs. through) is not the limiting factor for this tap type; material ductility is. (Source-bound)

Manufacturer-specific recommendations

  • Requires a ductile workpiece material -- commonly cited minimum elongation of roughly 8% and maximum hardness of roughly Rc 30 -- because threads are formed by plastic displacement, not cutting. (Source-bound)

Hand Tap

A tap designed for manual operation with a tap wrench, typically supplied as part of a set spanning taper, plug, and bottoming chamfer styles for a given thread size.

Typical applications

  • Designed for manual operation with a tap wrench; commonly supplied as a taper/plug/bottoming set for progressive blind-hole tapping by hand. (Source-bound)

Explore tap types

Learn how taper, plug, bottoming, spiral-flute, spiral-point, forming, and other tap types differ in geometry, application, and evidence.

Tap Type Guide

Standards

Standards references describe the documented relationship of the data record to the cited standard. They do not imply that every field on the record is directly specified by that standard.

  • ISO 965-1
  • ISO 261
  • ISO 262
  • ISO 724
  • ISO 2306 — Drills for use prior to tapping screw threads
  • ASME B1.1 — Unified Inch Screw Threads (UN, UNR, and UNJ Thread Forms)

Thread engagement

BoltLab can calculate radial thread engagement from thread geometry and drill diameter, but it does not currently provide a universal target engagement percentage. Axial engagement length calculations remain unavailable because the required material-strength data is not yet part of the dataset.

Data interpretation

  • Primary tap drill — the profile's main value, in its own labeled convention (metric drill convention for metric, US customary for UNC/UNF).
  • ISO 2306 alternative — shown only for UNC/UNF, always a separate value, never a replacement for the primary drill.
  • Verified (tap drill) — independently cross-checked against the cited primary source.
  • Source-bound (tap drill) — bound to a verified BoltLab source record, but not yet independently cross-checked against the primary standard.
  • Field-level vs. overall status — a profile's tap-drill value can be individually verified while the profile as a whole remains source-bound, because thread-engagement and tapping-process-parameter data are not yet available for any of the 29 profiles. The two states are shown separately on every card and are not the same claim.

Download

This download is generated from BoltLab's Tapping & Threading Atlas projection. Verification status is preserved at the field level.

Download tapping atlas CSV

Related tools

Related engineering references

FAQ

What is the BoltLab Tapping & Threading Atlas?

It is BoltLab's structured engineering data product for tapping and thread-preparation information across metric, UNC, and UNF threads, built from BoltLab's verified knowledge layer and projection pipeline rather than written as a general guide.

What tap-drill information does BoltLab provide?

Each record shows a primary tap-drill value in its own convention (the metric drill convention for metric, US-customary drill series for UNC/UNF), a verification status, and where applicable a separately labeled ISO 2306 alternative drill value for UNC/UNF threads.

Why are some tap-drill values source-bound?

Source-bound means a credible source supports the value, but it has not been independently cross-checked against a primary standard table in this phase. BoltLab labels these explicitly rather than presenting every value as equally certain.

What is the ISO 2306 alternative drill value?

For UNC and UNF threads, ISO 2306 provides its own metric drill-diameter recommendation using a different sizing convention than BoltLab's primary US-customary value. It is shown as a separate, independently verified field and does not replace or average with the primary value.

Does BoltLab provide a universal thread-engagement percentage?

No. BoltLab can calculate radial thread engagement from thread geometry and a chosen drill diameter, but it does not assert a universal target engagement percentage, and axial engagement length remains not calculable because the required material-strength data is not yet part of the dataset.

Can I download the tapping data?

Yes. The same projection data shown on this page is available as a CSV download, with verification status preserved at the field level.

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