Female To Female Thread Adapters And Reducers.

What are Female To Female Thread Adapters And Reducers?

Female to female thread adapters and reducers, also known as reducing coupling nuts or female thread converters, are part of Accu's thread adapters and reducers range, joining two mismatched male threads without altering either component. Each one is a hexagonal body with a tapped bore in each end face, and the two bores differ in size, pitch, standard or hand, so it looks like a long coupling nut whose holes do not match. Because the conversion is carried inside the adapter, a UNF stud on imported equipment can meet a metric rod on your own fixture with nothing retapped or remachined, and the joint can be undone at any point.

Imperial threads are cut to class 2B and metric threads to class 6H, the general-purpose tolerance classes for internal unified and ISO metric threads, so each end mates with standard studs, bolts and threaded rod from any supplier. That makes a female to female thread adapter a regular fixture on test rigs, calibration jigs and instrumentation set-ups, where sensors, actuators and frames built to different standards have to be joined quickly and separated again.

How Female to Female Thread Adapters Work.

Fitting one starts with the two male threads you need to join. The first is screwed fully into its matching bore, the second into the opposite bore, and a spanner on the hex flats brings the joint up tight, with a lock nut against each face where the assembly must not turn. Load then runs in a straight line from one stud, through the solid hex section between the bores and out through the other, keeping the connection on a single axis. Right to left versions carry the same metric coarse thread at both ends, but one end is left-handed. Turning the body pulls both studs in or drives them apart together, so length or tension can be set without rotating either rod.

Take a tensile test rig built around a US-made in-line load cell with a 3/8-24 UNF stud at each end, driven by a metric pneumatic cylinder whose piston rod ends in an M10 x 1.25 thread. A 3/8-24 UNF to M10 (1.25 mm Fine) female to female thread adapter screws onto the piston rod at one end and the load cell stud at the other, putting the sensor directly in line with the actuator inside a 38 mm long body with a 16 mm hex. Without it, the options are remachining the cylinder rod or sourcing a special load cell. Both cost far more time than the adapter does. This is the kind of job a metric to imperial thread adapter exists for and accounts for most of this range.

Materials Female to Female Thread Adapters Are Made From

Accu's range of female to female thread adapters is machined from engineering metals selected for clean thread form, corrosion resistance and, where it matters, low mass:

• Aluminium: The lightest option in the range at roughly a third of the weight of the equivalent stainless adapter, with natural corrosion resistance that suits moving fixtures, handheld instruments and weight-sensitive rigs.
• Stainless Steel - (303): A free-machining austenitic stainless steel to SS 303 / ASTM A582 that holds an accurate thread form and resists corrosion in indoor, workshop and general industrial conditions.
• Stainless Steel - Marine (A4): Specified to SS 316 / ASTM A276, this molybdenum-bearing grade gives the highest corrosion resistance in the range, standing up to salt water, washdown chemicals and humid test chambers.

The whole range is supplied in a Natural finish, and the Stainless Steel - (303) right to left adapters are also available in AccuBlack, a chemically blackened dark, low-reflectance finish suited to optical and camera equipment.

Sizes & Types of Female to Female Thread Adapters Available

Accu's range of female to female thread adapters covers imperial to metric conversions, metric reducers and right to left adapters across more than 200 thread pairings:

• Female Thread Specification (A): 6-32 UNC to 1/2-28 UNEF on imperial to metric adapters, M3 (0.35 mm Fine) to M12 (1.75 mm Coarse) on metric to metric adapters.
• Female Thread Specification (B): M2.5 (0.45 mm Coarse) to M16 (2 mm Coarse).
• Thread Specification: UNC, UNF or UNEF to metric coarse, fine or extra fine; metric to metric across coarse, fine and extra fine pitches; metric coarse to left-hand metric coarse.
• Thread Type: Imperial to Metric and Metric to Metric.
• Thread Class: 2B / 6H on imperial to metric adapters, 6H on metric to metric adapters.
• Socket Size (J): 8 mm to 21 mm.
• Thread Length (L): 11 mm to 75 mm.

Not every pairing is made in every material. Aluminium starts at 10-24 UNC on its imperial to metric adapters and at M6 on its metric thread reducers, so the smallest sizes, including every 6-32 UNC, 8-32 UNC, M2.5 and M3 option, come in Stainless Steel - (303) and Stainless Steel - Marine (A4) only. M16 (2 mm Coarse) is the largest thread in the range and pairs only with the three 1/2" imperial threads or with M12 (1.75 mm Coarse). Right to left adapters run from M4 to M12 in coarse pitch with the same size at each end, and there is no imperial to imperial option in the standard range.

If you're unsure which threads you're joining, Accu's guide on how to measure a screw will help you identify the size and pitch, and Accu's metric threaded bars supply the rod either side of the adapter. Where both studs share the same thread and no conversion is needed, browse Accu's range of connector nuts, a simpler alternative that couples two identical threads.

FAQ

Q: What is a right to left female to female thread adapter used for?

A: It joins two rods or studs of the same metric thread, one right-handed and one left-handed, so that turning the adapter's hex pulls both ends in or pushes them apart at once. That turnbuckle action sets the length of a tie rod or linkage, or puts tension into a stay, without either rod rotating. This matters when both rods are fixed to brackets or sensors at their far ends. Right to left adapters are available from M4 to M12 coarse in all three materials.

Q: Can I get an M10 to M8 or M6 to M4 female thread reducer?

A: Yes. The M10 to M8 female thread reducer comes in all six coarse, fine and extra fine combinations, pairing M8 (1.25 mm Coarse) or M8 (1 mm Fine) with M10 (1.5 mm Coarse), M10 (1.25 mm Fine) or M10 (1 mm Extra Fine). Every one is available in Aluminium, Stainless Steel - (303) and Stainless Steel - Marine (A4). The M6 to M4 thread reducer is a single part, M4 (0.7 mm Coarse) to M6 (1 mm Coarse) in Stainless Steel - (303). 

Q: Can you make custom thread adapters?

A: Yes. Where the pairing, length, material or finish you need is not in the standard range, such as an imperial to imperial female to female adapter or a longer body, Accu's custom manufacture service produces custom thread adapters to your drawing or specification, from small prototype batches to large-scale production.

Q: Should I choose an aluminium or stainless steel thread adapter?

A: Choose aluminium where mass matters, such as on moving fixtures, vibration test set-ups or handheld instruments in dry conditions. Stainless Steel - (303) suits most indoor and industrial rigs, while Stainless Steel - Marine (A4) is the choice for salt spray, washdown or outdoor sites where chlorides are present.

Bespoke Female To Female Thread Adapters And Reducers Manufacture.

High precision, bespoke manufacture of Female To Female Thread Adapters And Reducers to customer specification. State of the art facilities specializing in both small batch prototyping and large scale manufacture.