Key-locking thread inserts
Solid threaded bushings with keys that resist rotation in the host, distinct from optional screw-locking threads and other insert systems.
Tags: components, fasteners, thread-inserts
On this page
Jergens thinwall 26322 and Carr Lane heavy-duty CL-1420-SKSL both receive 1/4-20 screws. Their host threads are 3/8-16 and 7/16-14, respectively. Driven keys resist rotation of the insert in the host. The named Carr Lane locking variant separately resists rotation of the screw. Check the host drawing and key engagement for the exact insert. Jergens specifications, Carr Lane internal-thread-locking heavy-duty inserts.
Identity and the two threaded interfaces
A solid threaded bushing receives a screw internally and threads into the host externally. Carr Lane threaded-insert overview, Howmet Camloc KEENSERTS.
Driving the keys into the host resists insert rotation. A screw-locking variant adds a separate feature at the inner thread. Jergens Thinwall Industrial Style, Carr Lane internal-thread-locking heavy-duty inserts.
Axial screw load passes through the insert body and host thread. Check host material and engagement before assigning capacity.
Named geometry and material examples
Dimensions below identify particular catalog entries, rather than hole-preparation instructions. Inch thread callouts retain their catalog notation; lengths are inches.
| Manufacturer and named variant | Internal thread | External thread | Listed length |
|---|---|---|---|
| Jergens 26322, Thinwall Industrial Style, stainless steel | 1/4-20, class 2B | 3/8-16 | 0.37 |
| Jergens 26323, same family | 5/16-18, class 2B | 7/16-14 | 0.43 |
| Carr Lane CL-1420-SKSL, Heavy Duty, stainless steel, internal thread locking | 1/4-20 | 7/16-14 | 0.37 |
The Jergens entries and inch internal-thread class come from its Thinwall Industrial Style table. The Carr Lane entry comes from its internal-thread-locking inch table. The two 1/4-20 examples illustrate that the same screw thread and listed length can accompany different external threads; they are not a substitution pair.
Jergens lists this thinwall family's body options as C1215 or equivalent carbon steel with a Parkerized finish, or passivated 303 stainless steel; keys are 302 stainless steel. Its page states that inserts with internal threads of 5/16-18 or larger have four keys. That statement is specific to this family, not a universal threshold for every thread series. Jergens specifications.
Carr Lane lists 303 stainless bodies and 302 stainless keys for the cited locking heavy-duty inch family. Its material table uses dashes for heat treatment and finish; those marks do not establish a particular coating or heat-treatment condition. Carr Lane materials table. Howmet's Camloc overview describes two or four preassembled keys depending on external-thread size, without giving the size boundary on that page. Howmet overview.
Wall style, host material and retention
Carr Lane distinguishes thinwall inserts by a smaller external-thread diameter than its standard heavy-duty inserts, describing a space-versus-pull-out-strength trade-off. This is a manufacturer family comparison, not a numerical strength ratio. Its “solid” key-insert variant is a plug for relocating a hole; that usage differs from “solid-wall” describing a threaded bushing rather than a wire coil. Carr Lane thinwall; Carr Lane family overview.
Parent-material statements are not consistent enough to combine into a universal compatibility list. Howmet's Camloc overview includes cast iron among its examples, whereas Carr Lane's family overview advises against brittle materials including cast iron and plastic. These statements concern different named offerings; they do not resolve suitability for an unspecified insert and host. Howmet Camloc overview; Carr Lane overview.
Flange geometry, key count, wall thickness, coatings and installation details belong to an identified part and drawing revision. The HTML sources reviewed here do not establish a flanged-series dimensional specification. Likewise, catalog shear-engagement areas and marketing strength descriptions do not establish joint capacity without applicable host properties, engagement geometry and a failure criterion.
Other insert systems
| System | Distinguishing feature in the named source |
|---|---|
| Coiled-wire insert | Böllhoff HELICOIL Plus Free Running is a coil with a rhombic profile. The Plus Screwlock version adds polygonal turns that clamp the screw flanks; this is screw locking, distinct from keys driven into a host. Böllhoff HELICOIL. |
| Solid self-tapping insert | SPIROL Series 10 forms a receiving thread in plastic with its coarse external thread during insertion. It is a thread-forming system for the stated softer plastics, not the keyed, pre-tapped-host arrangement described above. SPIROL Series 10. |
| Heat or ultrasonic insert | SPIROL describes locally remelted plastic conforming to external retention features such as knurls and undercuts, then solidifying. That retention mechanism differs from driven mechanical keys in a threaded host. SPIROL installation comparison. |
These examples distinguish mechanisms. They do not imply equivalent hole sizes, tooling, retention or fastener reuse behavior across systems.
Source basis and coverage limits
Reviewed and retrieved 2026-10-30 PDT (America/Los_Angeles). The cited sources are manufacturer HTML product pages: Howmet's Camloc overview; Jergens Thinwall Industrial Style; Carr Lane's family, thinwall and locking-heavy-duty pages; Böllhoff's UK HELICOIL page; and SPIROL's Series 10 and installation-comparison pages. No explicit technical edition, publication date or update date was established for these live pages. The review date is not a source revision. Search crawl dates and site copyright years are not document editions.
Carr Lane's indexed search excerpt contained shorter product wording than the opened page; the opened page's application sections and product/material tables support the claims here. The Jergens page was available as extracted web text; a separate direct HTML request returned HTTP 403, so a raw origin copy was not available for that source. Indexed snippets and linked PDFs are not treated as inspected drawings or additional evidence. No PDF or full standard was relied upon. Carr Lane lists an MS equivalent for its example, but this article does not establish compliance with an unseen standard or purchaser acceptance requirements.
Coverage is identification, interface distinctions and the named examples. It does not provide a general drill/tap/countersink sequence, removal recipe, allowable load, locking torque, reuse-cycle limit, temperature or corrosion rating. Those remain dependent on the exact product revision, host condition, joint design and applicable qualification. No customer installation, material lot, approved repair or process capability is established by these reference sources.