Custom Cable Gland & Conduit Thread Adapters

When Standard Adapters Do Not Fit

Standard gland reducers exist in quantity and cost a couple of euros. If one of them fits your job, buy it — we would rather tell you that than sell you a machined part you do not need. What follows is the list of situations where they run out, and those are the ones we handle:

• The connector and the conduit fitting carry different threads, and no reducer covers that pair
• One side is a non-standard or fine pitch that is not part of any gland range
• Every available adapter is too long for the space between the connector and the housing
• The standard hex fouls a neighbouring gland, cable or casting rib
• The original adapter is discontinued and only the old part remains
• You have a photo or a sample, not a drawing
• You need 10 or 20 pieces, and the custom suppliers you asked want hundreds
• The specification calls for nickel-plated brass or 316L and the stock part is only nylon
• An existing sealing arrangement must be retained exactly as it is

Sizes We Convert Most

Two directions, two names. A reducer takes a larger entry down to a smaller one; an enlarger opens a small entry up to a bigger gland. Both are turned from solid here — and either can be male-to-female, female-to-female or male-to-male, whichever the two mating parts need. British spelling adaptor and American adapter mean the same part.

Conversion	Direction	Where it usually comes up
M12×1.5 → M16×1.5	Enlarger	Sensor or small connector entry into a standard gland
M16×1.5 → M20×1.5	Enlarger	The most common single step on motor terminal boxes
M20×1.5 → M25×1.5	Enlarger	Cable thicker than the original entry allows
M25×1.5 → M20×1.5	Reducer	Oversized knockout in an enclosure, smaller cable
M20×1.5 → M16×1.5	Reducer	Panel hole drilled for the previous gland size
M25×1.5 → M32×1.5	Enlarger	Retrofit to armoured or larger multicore cable
M32×1.5 → M25×1.5	Reducer	Existing gland plate reused for a smaller run
M40×1.5 → M32×1.5	Reducer	Drive and converter cabinets
PG16 → M20×1.5	Standard change	Older German equipment being re-glanded to metric
PG21 → M25×1.5	Standard change	Same, one size up
PG29 → M32×1.5	Standard change	Larger legacy conduit entries
1/2″ NPT → M20×1.5	Standard change	US-built machine installed under metric wiring practice
3/4″ NPT → M25×1.5	Standard change	Same, one size up
M15×1 → M16×1.5	Connector to gland	Connector thread that no gland range carries — see below

This list is what recurs, not a catalogue. Any pair of the threads in the panel above can be cut, in either direction, with a male or female end as required. If your combination is not shown, it is not a special case — state the two ends and we quote it the same way.

A Live Example — M15×1 Female to M16×1.5 Male

This is a request that reached us in July 2026 from a German drive and motor manufacturer. We are reproducing the technical content because it is a textbook version of the problem, and because it shows exactly what we need in order to quote.

Requirement	As stated by the customer
Female thread	M15×1, with 10 mm usable thread length
Male thread	M16×1.5, thread length under 8 mm
Hex	As small as possible — SW 22 mm suggested
Overall length	As short as the threads allow
Material	Nickel-plated brass preferred, 316L acceptable
Quantity	14 pieces
Function	Join an industrial connector to a protective conduit gland
Wanted first	A drawing for approval, then the price

Three things in that list are the whole reason a catalogue part cannot do the job:

M15×1 is not a cable gland size

Gland entry threads run M12, M16, M20, M25, M32 and the PG equivalents. M15×1 belongs to the connector, not to the gland world, so no gland-reducer range contains it. Single-pointing that thread on a lathe costs the same as cutting any other — it is only a program and a gauge.

Ten millimetres of usable thread is a real constraint

"Usable thread length" is not the same as thread length. Runout at the end of a female thread, and the chamfer at its mouth, both eat into what the mating part can actually engage. When a customer states 10 mm usable, the drawing has to show full-form thread over 10 mm and put the runout beyond it — otherwise the connector bottoms out two turns early.

Short body and small hex pull against each other

The male side needs under 8 mm of thread, the female side 10 mm of usable thread. Those two plus the wrench flats set the minimum overall length; there is nothing else to remove. The hex is the other lever: SW 22 across flats leaves enough wall around an M16×1.5 male thread to take assembly torque, and it clears more than the SW 24 or SW 27 a standard part would carry.

PG, Metric and NPT — Why Threads That Measure the Same Do Not Fit

This is the trap that sends most people looking for an adapter in the first place. PG (Panzergewinde, DIN 40430) is the older German steel-conduit thread and it is still all over installed equipment. Several PG sizes come out within half a millimetre of a metric gland thread on the caliper — and none of them will screw together. The pairs that catch people out most are PG13.5 against M20 and PG16 against M22.

PG size	Thread OD	Pitch	Panel hole	Cable range	Nearest metric gland
PG 7	12.5 mm	1.27 mm	12.7 mm	3.0–6.5 mm	M12×1.5
PG 9	15.2 mm	1.41 mm	15.5 mm	4.0–8.0 mm	M16×1.5
PG 11	18.6 mm	1.41 mm	19.0 mm	5.0–10.0 mm	M20×1.5
PG 13.5	20.4 mm	1.41 mm	20.8 mm	6.0–12.0 mm	M20×1.5
PG 16	22.5 mm	1.41 mm	22.8 mm	10.0–14.0 mm	M25×1.5
PG 21	28.3 mm	1.59 mm	28.6 mm	13.0–18.0 mm	M25×1.5
PG 29	37.0 mm	1.59 mm	37.3 mm	18.0–25.0 mm	M32×1.5
PG 36	47.0 mm	1.59 mm	47.3 mm	22.0–32.0 mm	M40×1.5
PG 42	54.0 mm	1.59 mm	54.4 mm	30.0–41.0 mm	M50×1.5
PG 48	59.3 mm	1.59 mm	59.6 mm	32.0–44.0 mm	M50×1.5

Metric cable gland threads are the simple case by comparison: M12, M16, M20, M25, M32, M40, M50 and M63 all run a 1.5 mm pitch under EN 60423, so the only variable between sizes is diameter. NPT is different again — it is tapered, sealing on the thread flanks themselves, which is why an NPT entry usually wants a shoulder and washer on the metric side rather than thread sealant alone. Tell us which of the three standards is on each end and whether the existing seal is a washer, an O-ring or the taper itself.

Designed for Confined Installation Space

Most of the value in a machined adapter is length that is not there. A catalogue part has to serve a whole size range, so it carries thread engagement, wall and wrench length for the worst case in that range. A part cut for one interface carries only what that interface needs. In practice we work these four levers:

Lever	What it buys you	What limits it
Thread engagement	Length off each end	Enough turns to carry the load and seal; we will not cut below what the joint needs
Across-flats	Radial clearance to neighbours	Wall thickness around the larger thread
Wall thickness	Smaller outside diameter	Assembly torque and, on brass, the plating process
Shoulder / seal face	Keeps the existing sealing arrangement	Must stay flat and square to the thread axis

Send the maximum length and maximum across-flats you can live with. We will tell you whether it is achievable, and if it is not, exactly which of the four is in the way.

What the Equipment Usually Dictates

The thread pair is only half the brief. Where the part is going decides material, length and how much wrench room you actually have.

Equipment	What usually drives the design	Typical spec
Motor terminal box	Cast housing ribs and the cooling fan shroud sit close to the entry, so the hex has to clear them and the body has to be short	M16/M20/M25, nickel-plated brass, reduced hex
Geared and servo motors	Entries clustered on a small face; a standard across-flats fouls the neighbouring gland	Short body, two spanner flats instead of a full hex
Drives & frequency converters	Bonding and screening continuity through the joint matters; plastic is often ruled out	Nickel-plated brass or 316L, metal-to-metal seat
Control cabinet gland plate	Holes already drilled for the previous build; the new gland does not match the hole	Reducer or enlarger with locknut face and panel shoulder
Sensors & instrumentation	Small threads, tight torque limits, sometimes an insulating requirement	M12/M16, or PA66 / POM / PTFE where isolation is needed
Pumps, compressors, conveyors	Vibration works fittings loose; washdown attacks plating	316L, O-ring groove, locking provision
Mining & heavy plant	Impact and dust; armoured conduit is heavy and levers on the joint	Heavier wall, full hex, steel or 316L
Marine & offshore	Salt air rules out brass and plated steel over time	316L throughout, sealing face specified
Legacy / retrofit equipment	Original entry is PG or an obsolete size; the replacement gland is metric	PG-to-metric in one body, copied from the old part

If you are re-glanding an older machine, the fastest route is usually to post us the fitting that is coming off. We measure the thread on it directly rather than working from a size you had to guess at — and a wrong guess on pitch is the most expensive mistake in this whole exercise.

What to Send Us

Six lines are enough for a firm quote. Use the form on this page or email [email protected]:

• Both threads — size and pitch, and whether each end is male or female
• Usable thread length needed at each end
• Maximum overall length available at the installation point
• Maximum across-flats, if something is in the way
• Material and finish — or describe the environment and we will propose one
• Quantity and delivery country

A photo with a caliper against the part covers most of that on its own. No CAD file is needed, and we issue a dimensioned drawing for your approval before anything is machined.

Frequently Asked Questions