ASME B18.3 Cup Point Set Screws (Inch Series)
ASME B18.3 hex socket set screws with cup point in the inch series, #0 to 2" — the full collected 24-size table with thread length, UNC/UNF/UNEF thread availability per size, key width, key engagement and cup point diameter.
Last updated: 2026-11
Specifications
The inch-series counterpart of ISO 4029 covers the same cup-point duty — highest standard-point grip on pulleys, collars and stops — across the American size ladder from #0 to 2 inches, twenty-four sizes in the collected table. What the inch standard adds over the metric page is the thread-series matrix: per size, the table prints the threads per inch available in UNC, UNF and UNEF, with a dash where a series does not cover the size — reproduced verbatim, including the unthreaded smallest sizes and the coarse-only 1-3/4" and 2" tops of the range. The rest of the geometry follows the familiar pattern: thread length d, socket key width s, key engagement t min, and cup point diameter d z max/min for hardness matching against the mating surface. The cup marks the shaft it grips — for repeatedly adjusted parts prefer a flat or dog point — but where the joint is set once and stays set, nothing standard holds harder. For the metric counterpart see the ISO 4029 page on this site; the flat-point DIN 913-line equivalents carry the same point-style trade-offs in both unit systems.
| Standard | ASME B18.3 — hexagon socket set screws with cup point (inch series) |
|---|---|
| Series | #0 – 2 in (24 sizes tabulated); UNC/UNF/UNEF threads-per-inch matrix per size, dashes where a series does not cover the size |
| Tabulated geometry | Per size: thread length d as printed, PP for UNC/UNF/UNEF, key width s nominal, key engagement t min, cup point diameter d z max/min |
| Point style | Cup point — sharp circular edge bites a seating ring; highest standard-point grip, permanent surface mark |
| Family note | Inch-series cup point set screw; metric counterpart ISO 4029 (M1.6–M24); flat/dog/cone point siblings under ISO 4026/4027/4028 |
| Materials / strength | Not tabulated by the collected specification — per RFQ (property class and stainless grade per drawing callout) |
| Screw thread | d — thread length (in) | PP — UNC | PP — UNF | PP — UNEF | s nominal (in) | t min (in) | d z max (in) | d z min (in) |
|---|---|---|---|---|---|---|---|---|
| 0 | 0.06 | - | 80 | - | 0.028 | 0.05 | 0.033 | 0.027 |
| 1 | 0.073 | 64 | 72 | - | 0.035 | 0.06 | 0.04 | 0.033 |
| 2 | 0.086 | 56 | 64 | - | 0.035 | 0.06 | 0.047 | 0.039 |
| 3 | 0.099 | 48 | 56 | - | 0.05 | 0.07 | 0.054 | 0.045 |
| 4 | 0.112 | 40 | 48 | - | 0.05 | 0.07 | 0.061 | 0.051 |
| 5 | 0.125 | 40 | 44 | - | 0.062 | 0.08 | 0.067 | 0.057 |
| 6 | 0.138 | 32 | 40 | - | 0.062 | 0.08 | 0.074 | 0.064 |
| 8 | 0.164 | 32 | 36 | - | 0.078 | 0.09 | 0.087 | 0.076 |
| 10 | 0.19 | 24 | 32 | - | 0.094 | 0.1 | 0.102 | 0.088 |
| 1/4 | 0.25 | 20 | 28 | 32 | 0.125 | 0.125 | 0.132 | 0.118 |
| 5/16 | 0.3125 | 18 | 24 | 32 | 0.156 | 0.156 | 0.172 | 0.156 |
| 3/8 | 0.375 | 16 | 24 | 32 | 0.188 | 0.188 | 0.212 | 0.194 |
| 7/16 | 0.4375 | 14 | 20 | 28 | 0.219 | 0.219 | 0.252 | 0.232 |
| 1/2 | 0.5 | 13 | 20 | 28 | 0.25 | 0.25 | 0.291 | 0.27 |
| 5/8 | 0.625 | 11 | 18 | 24 | 0.312 | 0.312 | 0.371 | 0.347 |
| 3/4 | 0.75 | 10 | 16 | 20 | 0.375 | 0.375 | 0.45 | 0.425 |
| 7/8 | 0.875 | 9 | 14 | 20 | 0.5 | 0.5 | 0.53 | 0.502 |
| 1 | 1 | 8 | 12 | 20 | 0.562 | 0.562 | 0.609 | 0.579 |
| 1-1/8 | 1.125 | 7 | 12 | 18 | 0.562 | 0.562 | 0.689 | 0.655 |
| 1-1/4 | 1.25 | 7 | 12 | 18 | 0.625 | 0.625 | 0.767 | 0.733 |
| 1-3/8 | 1.375 | 6 | 12 | 18 | 0.625 | 0.625 | 0.848 | 0.808 |
| 1-1/2 | 1.5 | 6 | 12 | 18 | 0.75 | 0.75 | 0.926 | 0.886 |
| 1-3/4 | 1.75 | 5 | - | - | 1 | 1 | 1.086 | 1.039 |
| 2 | 2 | 4.5 | - | - | 1 | 1 | 1.244 | 1.193 |
Materials
- Material, property class and finish specified per RFQ — the collected specification table covers geometry only
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (ASME B18.3 Cup Point Set Screws (Inch Series)) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
How do I read the UNC/UNF/UNEF columns in the table?
Each column gives the threads per inch the standard provides in that series at that size — a #10 cup point set screw comes 24 TPI coarse (UNC), 32 TPI fine (UNF), and not at all in extra-fine, while 1/4" exists in all three (20/28/32). The dash is the standard saying the size is not made in that series, not an availability gap — reproduced as printed. Pick the series from the mating design: fine and extra-fine threads give finer setting adjustment on the same wrench input, which matters on precision stops; coarse threads are the default for general clamping.
What should an RFQ for ASME B18.3 cup point set screws state?
The designation (ASME B18.3), size and thread series per the table (e.g. 1/4-28 UNF), length, material and property class or stainless grade, finish, and quantity per size. Note the table carries geometry and thread data only — length availability is confirmed at quotation; commercial terms follow the quotation.
What is the MOQ and lead time for these screws?
Minimum order quantity is 10,000 pieces per item. Stocked sizes ship in 3–7 days; non-stock diameters, lengths or finishes are quoted with a confirmed schedule. Common sizes in this designation are widely stocked — confirm the exact schedule against quantity and size mix at quotation.
Related knowledge
- Thread-Forming vs Thread-Cutting vs Thread-Rolling Self-Tapping Screws: What the Evidence Settles on Base Material
- Screw Family Selection by Base Material: Wood, Machine and Self-Tapping Threads, Engagement and Coating
- Hex Bolts vs Socket Head Cap Screws: What the Evidence Settles on Strength, Clearance and Cost
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support