Storage racks and machine area
Request diameter, TPI, UNC/UNF/BSW and spiral flute on the packing identification. This matters especially for nominally similar items such as 1/4-20 UNC and BSW.
THREADING TOOLS / INDUSTRIAL PROCUREMENT
UNC UNF and BSW Spiral Flute Tap
Keep UNC, UNF and Whitworth threads separate when replenishing blind-hole tap stock.
This inch-thread spiral flute series brings UNC, UNF and BSW designations into one 15-entry selection table. It serves blind-hole enquiries that require chips to return towards the entrance. The diameter, threads per inch and thread family must travel together on every order line.
15 defined entriesSize-by-size dimensions for an identifiable purchasing list.
HSS / HSS-CoTie the tool-material requirement to the selected application.
Order-line controlKeep the approved geometry and quantities together for replenishment.
- Spiral flute design for blind hole threading.
- UNC, UNF and BSW thread specifications.
- 60° American and 55° British Whitworth thread profiles.
- Material requirement selected with the requested thread execution.
PRODUCT SELECTION
Sizes, Dimensions & Drive Interface
Dimensions are in millimetres except thread designations, drive labels and lead counts. Read each column with the dimension reference below.
| Thread / designation | Overall length L (mm) | Working / cutting length Lc (mm) | Listed diameter d (mm) | Square / drive k (mm) | Pilot reference (mm) |
|---|---|---|---|---|---|
| 4-40 UNC | 44 | 8.5 | 3 | 2.5 | 2.3 |
| 6-32 UNC | 48 | 13 | 4 | 3.2 | 2.8 |
| 8-32 UNC | 52 | 13 | 5 | 4 | 3.4 |
| 10-24 UNC | 60 | 16 | 5.5 | 4.5 | 3.9 |
| 10-32 UNF | 60 | 16 | 5.5 | 4.5 | 4.1 |
| 1/4-20 UNC | 62 | 19 | 6 | 4.5 | 5.1 |
| 5/16-18 UNC | 70 | 22 | 6.1 | 5 | 6.6 |
| 3/8-16 UNC | 75 | 24 | 7 | 5.5 | 8 |
| 1/2-13 UNC | 85 | 29 | 9 | 7 | 10.8 |
| 1/8-40 BSW | 44 | 8.5 | 3 | 2.5 | 2.65 |
| 3/16-24 BSW | 60 | 16 | 5.5 | 4.5 | 3.75 |
| 1/4-20 BSW | 62 | 19 | 6 | 4.5 | 5.1 |
| 5/16-18 BSW | 70 | 22 | 6.1 | 5 | 6.6 |
| 3/8-16 BSW | 75 | 24 | 7 | 5.5 | 8 |
| 1/2-12 BSW | 85 | 29 | 9 | 7 | 10.7 |
Match pilot-hole preparation to the thread system, workpiece and agreed acceptance requirement.
Compare L, Lc, d and k size by size; overall lengths run from 44 to 85 mm. At 1/4-20, UNC and BSW have similar listed dimensions but different thread profiles.
Send the sizes and dimensions your customer needs.Request a Quote →
PRODUCT SELECTION
Application, Chip Path & Selection Limits
Match the component and operation
Use the spiral flute form to review chip removal from closed-bottom holes. UNC and UNF have 60° profiles; BSW uses a 55° Whitworth profile. Include the workpiece grade and the exact mating-thread designation.
Check the operating boundary
A shared nominal diameter does not make UNC, UNF and BSW interchangeable. Even matching TPI can conceal a different flank angle. HSS and HSS-Co requirements should be specified for the requested configuration, not inferred from colour.
PRODUCT SELECTION
Compare the Adjacent Product Families
| Product family | Selection boundary to review |
|---|---|
| UNC UNF and BSW Spiral Point Tap | For inch through-hole orders, match the thread family and leave space for forward-moving chips. |
| HSS Metric Spiral Flute Machine Tap | General metric return-chip spiral flute series for blind-hole selection; retain the published dimensions. |
| HSS BSP Parallel and Taper Pipe Thread Tap | Separate parallel G and tapered ZG requirements before sourcing a pipe-thread tap. |
Keep the selected family, thread designation and dimensional reference together. Shared nominal sizes or drive shapes do not establish interchangeability.
WORKSHOP & SUPPLIER REVIEW
Workshop, Material Handling & Order Organisation
In an inch-thread stock programme, thread-family identification is an order-control issue. Keep the 55° BSW family separate from 60° UNC/UNF items while discussing sample matching and size-by-size replenishment.
Bar-stock handling
Carry the HSS / HSS-Co requirement with the item drawing when discussing material preparation for this range.
Component feed and transfer
Keep the approved item identity and dimensional revision with components during order discussions. Use the exact thread and drive dimensions to distinguish similar tools.
Plan the order around the approved item
- Define the thread and application using this product’s selection table.
- Compare the tool interface and cutting geometry with the sample or drawing.
- Agree sample acceptance, quantities by size and the requested pack arrangement.
- Reference the same approved item and revision for replenishment.
QUALITY & SAMPLE ACCEPTANCE
Quality Review for the Selected Specification
Prioritise thread-family identification and TPI in sample acceptance. Holder dimensions are a separate check; a tap fitting the same chuck does not establish compatibility with the customer’s internal thread.
Use the following items to define the sample and order acceptance brief.
| Review item | What to agree | Procurement risk addressed |
|---|---|---|
| Thread identification | UNC/UNF/BSW, nominal size and TPI | Avoid the wrong thread family or pitch |
| Dimensions and holding | Compare L, Lc, d and k size by size; overall lengths run from 44 to 85 mm. At 1/4-20, UNC and BSW have similar listed dimensions but different thread profiles. | Avoid holder mismatch, insufficient reach or unintended substitution |
| Geometry / set identity | Prioritise thread-family identification and TPI in sample acceptance. Holder dimensions are a separate check; a tap fitting the same chuck does not establish compatibility with the customer’s internal thread. | Avoid the wrong cutting form or incomplete member sequence |
| Sample acceptance plan | Agree the reference drawing, acceptance method and sampling requirement for the application | Make sample approval and repeat-order review refer to the same item |
PROCUREMENT & REPLENISHMENT
Packaging, Custom Requests & Bulk Purchasing
Keep the packing brief specific
Use a separate stock line for each full inch-thread designation. For mixed wholesale orders, keep UNC/UNF/BSW labels visible in the packing brief so similar-diameter taps remain distinguishable during picking and restocking.
Marking, packs & repeat orders
Request diameter, TPI, UNC/UNF/BSW and spiral flute on the packing identification. This matters especially for nominally similar items such as 1/4-20 UNC and BSW.
Turn the selection into a clear purchasing list
Keep UNC, UNF and Whitworth threads separate when replenishing blind-hole tap stock.
SELECTION & BUYER QUESTIONS
Product Questions
Are UNC and BSW taps interchangeable at the same TPI?
No. UNC uses a 60° profile and BSW uses 55°. Diameter and TPI alone are not a complete thread specification.
Is an inch-size spiral flute tap intended for blind holes?
The spiral flute form helps move chips towards the entrance, making it relevant to blind-hole selection. Check lead allowance, workpiece material and full-thread depth.
Which UNF size is listed?
The table includes 10-32 UNF. Do not infer a complete UNF range from this mixed UNC/UNF/BSW list.
Can I order this as a metric spiral flute replacement?
Only if the component thread requirement is changed and verified separately. An inch designation is not interchangeable with a nearby metric diameter.
Why must the thread series appear on the packing list?
A 1/4-20 UNC item and a 1/4-20 BSW item share a nominal size and TPI but have different profiles. Explicit series labels reduce picking ambiguity.
What extra information is needed for a BSW blind-hole enquiry?
State BSW, nominal diameter and TPI, workpiece, drilled depth, full-thread depth and holder dimensions. Include quantity and the requested material specification.
PRODUCT ENQUIRY
Request a Quote for UNC UNF and BSW Spiral Flute Tap
Send the selected thread designation, quantities and the application details below. Add a drawing or size list to keep the enquiry tied to the required configuration.