Threaded Insert Fitted Height (UNC Threads)
Installed insert fitted height per UNC designation 2-56 through 1/2-13 — the installed insert's reach for engagements from 1d to 3d, on the same drill and tap data grid as the UNC drilling-depth chart.
Specifications
The UNC fitted-height companion: for each UNC coarse designation from 2-56 through 1/2-13, the installed insert height at engagements of 1d, 1.5d, 2d, 2.5d and 3d (d = nominal major diameter), tabulated against the same drill bit, drilled-diameter and tap outer-diameter columns as the UNC drilling-depth chart — shared grid, verified cell-for-cell. This is the inspection-side number for inch-series insert work: after installation, the fitted height is what you measure or gauge against to confirm the insert sits where the drawing wants it, whether that is flush under a cover plate or a set distance down a counterbore. Read it as a pair with the UNC drilling-depth page: engagement from the joint, depth from that chart, fitted height from this one. Pitch prints in millimetres as on the sibling chart. Insert length selection against a required fitted height is an RFQ line.
| Coverage | 22 UNC coarse designations, 2-56 through 1/2-13 — same ladder as the UNC drilling-depth chart |
|---|---|
| Chart column | Insert fitted height at 1d / 1.5d / 2d / 2.5d / 3d engagement, mm as printed (no sub-1d columns on the UNC charts) |
| Shared columns | Pitch (mm); drill bit diameter; drilling diameter min./max.; tap minimum outer diameter — identical values across the UNC drilling-depth and fitted-height charts (cross-checked, 0 diffs) |
| Not tabulated | UNF companions on their own page; insert lengths, flushness classes — per RFQ |
| Nominal Diameter | Pitch (mm) | Drill Bit Diameter (mm) | Drilling Diameter | Tap | Insert Fitted | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| min. | max. | Min Outer Diameter | 1d | 1.5d | 2d | 2.5d | 3d | |||
| 2-56 | 0.453 | 2.4 | 2.30 | 2.50 | 2.77 | 1.7 | 2.8 | 3.9 | 5.0 | 6.1 |
| 3-48 | 0.529 | 2.7 | 2.65 | 2.80 | 3.20 | 2.0 | 3.2 | 4.5 | 5.8 | 7.0 |
| 4-40 | 0.635 | 3.1 | 3.00 | 3.15 | 3.67 | 2.2 | 3.6 | 5.1 | 6.5 | 7.9 |
| 5-40 | 0.635 | 3.4 | 3.33 | 3.50 | 4.00 | 2.5 | 4.1 | 5.7 | 7.3 | 8.9 |
| 6-32 | 0.794 | 3.8 | 3.68 | 3.89 | 4.54 | 2.7 | 4.5 | 6.2 | 8.0 | 9.7 |
| 8-32 | 0.794 | 4.4 | 4.34 | 4.52 | 5.20 | 3.4 | 5.5 | 7.5 | 9.6 | 11.7 |
| 10-24 | 1.058 | 5.2 | 5.06 | 5.28 | 6.20 | 3.8 | 6.2 | 8.6 | 11.0 | 13.4 |
| 12-24 | 1.058 | 5.8 | 5.72 | 5.92 | 6.86 | 4.4 | 7.1 | 9.9 | 12.6 | 15.4 |
| 1/4-20 | 1.270 | 6.7 | 6.62 | 6.86 | 8.00 | 5.1 | 8.2 | 11.4 | 14.6 | 17.8 |
| 5/16-18 | 1.411 | 8.4 | 8.24 | 8.49 | 9.77 | 6.5 | 10.5 | 14.5 | 18.4 | 22.4 |
| 3/8-16 | 1.588 | 10.0 | 9.89 | 10.12 | 11.59 | 7.9 | 12.7 | 17.5 | 22.2 | 27.0 |
| 7/16-14 | 1.814 | 11.6 | 11.51 | 11.78 | 13.47 | 9.3 | 14.9 | 20.4 | 26.0 | 31.5 |
| 1/2-13 | 1.954 | 13.2 | 13.12 | 13.40 | 15.24 | 10.7 | 17.1 | 23.4 | 29.8 | 36.1 |
| 9/16-12 | 2.117 | 14.9 | 14.75 | 15.03 | 17.04 | 12.2 | 19.3 | 26.5 | 33.6 | 40.7 |
| 5/8-11 | 2.309 | 16.5 | 16.38 | 16.68 | 18.88 | 13.6 | 21.5 | 29.4 | 37.4 | 45.3 |
| 3/4-10 | 2.540 | 19.8 | 19.60 | 19.91 | 22.35 | 16.5 | 26.0 | 35.5 | 45.1 | 54.6 |
| 7/8-9 | 2.822 | 23.0 | 22.84 | 23.18 | 25.89 | 19.4 | 30.5 | 41.6 | 52.7 | 63.8 |
| 1″-8 | 3.175 | 26.4 | 26.09 | 26.47 | 29.53 | 22.2 | 34.9 | 47.6 | 60.3 | 73.0 |
| 1″ 1/8-7 | 3.629 | 29.5 | 29.36 | 29.74 | 33.29 | 24.9 | 39.2 | 53.2 | 67.8 | 82.0 |
| 1″ 1/4-7 | 3.629 | 32.8 | 32.54 | 32.92 | 36.46 | 28.1 | 44 | 59.9 | 75.7 | 91.6 |
| 1″ 3/8-6 | 4.234 | 36.2 | 35.84 | 36.35 | 40.42 | 30.7 | 48.2 | 65.7 | 83.0 | 100.5 |
| 1″ 1/2-6 | 4.234 | 39.5 | 39.02 | 39.53 | 43.62 | 33.9 | 52.9 | 72 | 91.0 | 110.0 |
Materials
- Geometry chart — the insert material decision follows the family pages (carbon steel, stainless A2/A4, exotic alloys). Quote parent material and required installed height with the UNC callout on the RFQ
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 (Threaded Insert Fitted Height (UNC Threads)) 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 quantities and lead times for this family are confirmed at quotation — send your sizes, grades and quantities on the RFQ and the quote will carry a firm schedule. Sample availability is confirmed with the 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
What does fitted height tell me that drilling depth does not?
Drilling depth is what the machinist cuts; fitted height is what inspection and the mating design see after install. A cover gasket that must seat on the parent face around the insert cares about fitted height: if the insert stands proud of the intended height, the gasket bridges the insert instead of sealing on the parent, and the joint leaks or loosens. A counterbored installation cares in the other direction — the insert must reach down to the counterbore floor or the screw bottoms on unthreaded parent. Neither check is possible from drilling depth alone, which is why the source splits the grid. On the UNC chart both numbers read at the same designation and engagement, so the pairing is one row each: depth from the drilling-depth page, height from this one, and the drawing shows how they stack.
The engagement I need sits between two columns — which fitted height applies?
Neither directly: the columns tabulate whole engagements (1d, 1.5d, 2d, ...), and a half-step need means the design is between the tabulated inserts. The honest options are to move the design to the next tabulated engagement (usually the right answer — the cost difference between 1.5d and 2d is one length class of insert) or to take it as an RFQ line where the required fitted height is stated explicitly and the insert length is quoted against it rather than read from a column. What you should not do is interpolate the fitted height and order the interpolated length: inserts are supplied in discrete lengths (1d, 1.5d, 2d, 2.5d, 3d classes), so the physical installed height will be the tabulated value of the length you bought, not your interpolation. Match the design to a column, or spec the height and quote.
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