Custom Thread Adapters

When the Two Threads Just Won't Meet

Equipment from different countries and eras rarely shares a thread standard. You end up with a British BSP port on one side and an American NPT or a metric fitting on the other — and the adapter that bridges them isn't on any shelf. EKINSUN machines that part to order — call it a threaded adapter, thread converter or threaded connector, it's the same job — with the correct thread and seal on each end.

Give us the two threads (or a sample of each side) and the medium it carries; we make the link that fits and seals.

Conversions We Machine

Common Conversions & Special Threads

The combinations engineers ask us for most — each machined to order in the size, hand and material you specify:

Conversion / type	Typical use
NPT ↔ metric	Joining US/imperial-threaded equipment to ISO metric ports — e.g. a custom 1/4" NPT to M12×1.5 thread adapter
BSP ↔ UNF	British pipe thread to UNF/UN fine, common on imported machinery and instrumentation
Left-hand thread adapters	LH threads for gas (fuel/acetylene), rotating shafts and anti-loosening joints — single-point cut to the exact hand and pitch
Custom / non-standard pitch	Odd or obsolete pitches converted or reproduced when no standard tap or die exists — cut to your measured pitch

Not sure of the exact standard, hand or pitch? Send a sample and we identify it for you — see how we reverse engineer an unknown thread.

Metric size conversions — M6, M8, M10, M12 and up

Stepping between two metric sizes is the request we machine most often. An M8 to M10 thread adapter, an M8 to M6 reducer or an M10 to M12 step-up bush — male-to-female, male-to-male or female-to-female, in standard or fine pitch:

Size pair	Notes
M6 ↔ M8	Small fixtures, camera and lamp mounts, sensor bosses — either direction, any pitch
M8 ↔ M10	The most requested pair — mirror stems, machine feet, stud extensions
M10 ↔ M12	Automotive sensors, hydraulic ports, mounting studs — standard or fine pitch (M12×1.25 / M10×1)
M12 ↔ M16 and larger	Structural studs, tooling, machine spindles — solid one-piece adapters up to M100

Every adapter is turned from solid and single-point threaded, so any pair and pitch is available — including combinations no catalogue stocks. One piece is fine.

Cable gland thread adapters

Enclosure entry doesn't match your gland? We machine cable gland thread adapters and reducers — metric (M16, M20, M25, M32) to PG, NPT or BSP, in brass, nickel-plated brass, stainless or aluminium, with O-ring seats or sealing washers to preserve the IP rating. Enlarger and reducer styles, short-pattern for shallow enclosures, one-off or batch.

Buying in French or Spanish? The same adapters are covered in adaptateurs de filetage sur mesure and adaptadores de rosca a medida, with local thread standards and terminology.

Material & Finish Options

We machine thread adapters in the material your line demands, with finishing to match:

• 316 stainless — corrosion, marine, chemical and food-grade lines (316 machining)
• Brass — general fluid, air and water, available in small batches with no strict MOQ
• Aluminium 6061 / 7075 — where weight matters, with optional anodised finish for wear and corrosion resistance
• Carbon / alloy steel — for higher-pressure and hydraulic builds (see hydraulic adapters)

Getting the Seal Right

An adapter only earns its place if it doesn't leak. We machine the correct sealing feature for each standard:

Thread	How it seals
NPT / BSPT	Tapered thread — seals on the thread flanks (PTFE/sealant aided)
BSPP (G)	Parallel — seals on a bonded washer, O-ring or 30° cone
JIC / SAE	37° flare cone / O-ring boss
Metric	Flat, cone or O-ring depending on the port

Note that BSPT and NPT look similar but differ in taper and thread angle, so they aren't interchangeable — we machine a true converting adapter, not a forced fit.

Real parts from our shop

A few thread adapters that recently left our machines — click any photo to enlarge.

Frequently Asked Questions