Threaded Insert Fitted Height (UNF Threads)
Installed insert fitted height per UNF designation 2-64 through 1/2-20 — the installed insert's reach for engagements from 1d to 3d, on the same drill and tap data grid as the UNF drilling-depth chart.
Specifications
The UNF fitted-height chart closes out the inch-series insert set: for each UNF designation 2-64 through 1/2-20, the installed insert height at 1d to 3d engagement, on the same shared machining grid as the UNF drilling-depth chart (drill bit diameter, drilled diameter min./max., tap minimum outer diameter — cross-checked cell-for-cell, zero differences). The use is the same as its UNC sibling — the inspection-side number confirming the installed insert sits where the drawing wants it — with the fine-pitch caveat that UNF installations often serve thin-wall or vibration-sensitive parents, where the fitted-height check matters more because there is less parent material to hide a seating error in. Read designation-to-designation (full callout: nominal + TPI), pair with the UNF drilling-depth chart at the same engagement, and flag any design that needs a height between tabulated engagements as an RFQ line rather than an interpolation. Pitch prints in millimetres as on the sibling charts.
| Coverage | 21 UNF fine designations, 2-64 through 1/2-20 — same ladder as the UNF drilling-depth chart |
|---|---|
| Chart column | Insert fitted height at 1d / 1.5d / 2d / 2.5d / 3d engagement, mm as printed |
| Shared columns | Pitch (mm); drill bit diameter; drilling diameter min./max.; tap minimum outer diameter — identical values across the UNF drilling-depth and fitted-height charts (cross-checked, 0 diffs) |
| Not tabulated | Insert lengths, flushness classes, parent-material corrections — 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 | |||
| 2-64 | 0.396 | 2.3 | 2.29 | 2.44 | 2.70 | 1.8 | 2.9 | 4.0 | 5.0 | 6.2 |
| 3-56 | 0.453 | 2.7 | 2.62 | 2.77 | 3.10 | 2.0 | 3.3 | 4.6 | 5.8 | 7.1 |
| 4-48 | 0.529 | 3.0 | 2.97 | 3.14 | 3.53 | 2.3 | 3.7 | 5.2 | 6.6 | 8.0 |
| 6-40 | 0.635 | 3.8 | 3.66 | 3.81 | 4.33 | 2.9 | 4.6 | 6.4 | 8.1 | 9.9 |
| 8-36 | 0.706 | 4.4 | 4.32 | 4.47 | 5.08 | 3.4 | 5.5 | 7.6 | 9.7 | 11.8 |
| 10-32 | 0.794 | 5.1 | 5.00 | 5.16 | 5.86 | 4.0 | 6.5 | 8.9 | 11.3 | 13.7 |
| 1/4-28 | 0.907 | 6.7 | 6.55 | 6.72 | 7.53 | 5.5 | 8.6 | 11.8 | 15.0 | 18.1 |
| 5/16-24 | 1.058 | 8.3 | 8.17 | 8.35 | 9.31 | 6.9 | 10.9 | 14.9 | 18.8 | 22.7 |
| 3/8-24 | 1.058 | 9.9 | 9.75 | 9.93 | 10.90 | 8.4 | 13.2 | 18.0 | 22.8 | 27.5 |
| 7/16-20 | 1.270 | 11.5 | 11.39 | 11.59 | 12.76 | 9.8 | 15.4 | 20.9 | 26.5 | 32.0 |
| 1/2-20 | 1.270 | 13.1 | 12.97 | 13.16 | 14.35 | 11.4 | 17.8 | 24.1 | 30.5 | 36.8 |
| 9/16-18 | 1.411 | 14.7 | 14.59 | 14.79 | 16.12 | 12.9 | 20.1 | 27.2 | 34.4 | 41.4 |
| 5/8-18 | 1.411 | 16.3 | 16.18 | 16.38 | 17.71 | 14.5 | 22.4 | 30.4 | 38.3 | 46.2 |
| 3/4-16 | 1.588 | 19.5 | 19.39 | 19.60 | 21.11 | 17.5 | 27.0 | 36.5 | 46.0 | 55.6 |
| 7/8-14 | 1.814 | 22.7 | 22.62 | 22.84 | 24.58 | 20.4 | 31.5 | 42.7 | 53.8 | 64.8 |
| 1″-14 | 1.814 | 26.0 | 25.86 | 26.11 | 27.76 | 23.6 | 36.3 | 49.0 | 61.7 | 74.4 |
| 1″-12 | 2.117 | 26.0 | 25.86 | 26.11 | 28.15 | 23.3 | 36.0 | 48.7 | 61.4 | 74.0 |
| 1″ 1/8-12 | 2.117 | 29.2 | 29.03 | 29.29 | 31.33 | 26.5 | 40.7 | 55.0 | 69.3 | 83.6 |
| 1″ 1/4-12 | 2.117 | 32.4 | 32.21 | 32.21 | 34.50 | 29.7 | 45.5 | 61.4 | 77.2 | 93.1 |
| 1″ 3/8-12 | 2.117 | 35.5 | 35.38 | 35.38 | 37.68 | 32.8 | 50.3 | 67.8 | 85.2 | 102.6 |
| 1″ 1/2-12 | 2.117 | 38.7 | 38.56 | 38.56 | 40.85 | 36.0 | 55.1 | 74.1 | 93.1 | 112.2 |
Materials
- Geometry chart; the insert is the material decision — carbon steel, stainless A2/A4 and exotic alloys per the family pages. State parent material and required installed height with the full UNF 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 (UNF 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
My UNF insert installed 0.4 mm proud of the fitted height on this chart. Reinstall or accept?
First check what you installed against what the drawing called: the fitted height is engagement-specific, so a 2d insert in a hole cut for 1.5d stands one length class proud, and the fix is the right insert, not rework of a correct one. If the lengths match and the height is still off, the usual suspects are an over-drilled or over-tapped hole (check the drilled-diameter min./max. limits on the UNF drilling-depth chart — a fine-pitch UNF hole above its max installs shallow) or debris/coil stacking at install. What the chart cannot tell you is the drawing's tolerance intent: the tabulated fitted height is the nominal the source prints, and whether 0.4 mm proud is acceptable is a gasket-sealing and assembly question answered by the drawing. Quote the measured height, the installed designation and length on the RFQ and the disposition is made against the installation spec, not against this table alone.
Why is the UNF fitted height lower than UNC at the same nominal size and engagement?
Because the thread is finer: d is the nominal major diameter in both series, but the installed insert's height tracks the thread turns and coil geometry of the specific pitch — a 1/4-28 UNF insert at 1d engagement presents fewer, tighter turns than a 1/4-20 UNC, and the tabulated heights reflect each series' own installed geometry. This is another reason the series never interchange: the drilling-depth chart and fitted-height chart of the wrong series would both mislead, in different directions. Take both numbers from the same series' pages, matched on the full designation, and if a repair drawing mixes UNC and UNF inserts on one housing, work the two series' charts side by side — that is exactly why we publish the four inch-series pages as a matched set.
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