Replacing a bearing and the locknut is seized, lost or a size nobody stocks? Rebuilding a machine spindle whose adjusting nut is long obsolete? Send the old nut or the shaft thread for a quote in 24 hours — we single-point the thread to match.
When the Standard Locknut Doesn't Exist
Bearing lock nuts and spindle nuts live by the catalogue — until the catalogue runs out. The KM and AN series cover the common bearing bores, but step outside them and the part vanishes: a shaft thread finer or coarser than the series pitch, a diameter above the largest KM, a machine-tool spindle nut the OEM stopped making decades ago, a left-hand adjusting nut, or a nut that needs extra height for more thread engagement. Standard shelves don't carry it, and no tap or die exists for the odd pitch.
EKINSUN machines it. We make custom bearing lock nuts and spindle nuts — round slotted (hook-spanner) nuts, precision set-screw and wedge locknuts, adjusting and retaining nuts — single-pointed to your exact thread and pitch, in the diameter, height and slot pattern you need. Reproduced from your old nut or the shaft it threads onto, no CAD file or part number required, one piece or a batch, quoted within 24 hours.
Nuts We Machine
Bearing lock nut (KM/AN)
Round slotted hook-spanner nut for bearing retention — any KM/AN size or beyond.
Spindle nut
Machine-tool spindle adjusting and retaining nuts, obsolete or non-standard.
Round slotted nut (DIN 1804)
Hook or face-spanner nut for bearings, pulleys and shaft ends.
Precision locknut
Set-screw, nylon-insert or wedge-segment locking for zero-backlash preload.
Oversized / tall nut
Extra height or wall for more thread engagement and higher preload.
Left-hand & special pitch
LH thread, extra-fine or odd pitch, single-pointed to match the shaft.
Series & Standards We Match
You don't need to identify the series — send the nut or shaft and we measure it. If you know the standard, here is what we reproduce:
| Series / Standard | What it is | What we match |
|---|---|---|
| KM (DIN 981) | Metric round slotted bearing locknut, KM0–KM40 and beyond | Metric fine thread, OD, height, slot count & width |
| AN (inch) | Imperial bearing locknut series (N-00 up) | Inch thread, slot pattern, tab-washer keyway |
| DIN 1804 | Slotted round nut / hook-spanner nut | Thread, face or side slots, spanner fit |
| MB / AN tab washer | Tongued lock washer that pairs with the nut | Bore tongue, OD tabs — supplied with the nut |
| Non-standard / OEM | Obsolete spindle nuts with no published spec | Reverse engineered from your old nut or shaft |
KM Series Thread Reference (typical)
| Size | Thread | Size | Thread |
|---|---|---|---|
| KM0 | M10 × 0.75 | KM5 | M25 × 1.5 |
| KM1 | M12 × 1 | KM6 | M30 × 1.5 |
| KM2 | M15 × 1 | KM7 | M35 × 1.5 |
| KM3 | M17 × 1 | KM8 | M40 × 1.5 |
| KM4 | M20 × 1 | KM9+ | M45 × 1.5 and up |
Need a thread between series sizes, a left-hand version, or a size above KM40? That's exactly what we machine — the reference above is only where the standard shelf stops.
Materials
| Material | Best for | Notes |
|---|---|---|
| Medium-carbon / alloy steel | Standard bearing & spindle nuts | Strength and thread-wear resistance; can be plated or blackened |
| 304 stainless | Washdown, food, humid or outdoor service | General corrosion resistance |
| 316 stainless | Marine and chemical service | Chloride resistance for seawater and coastal plant |
| Brass | Where a softer nut must protect the shaft thread | Non-galling, good for adjustment nuts |
| 6061 / 7075 aluminium | Lightweight spindles — motorsport, aerospace | 7075 where preload load is high and weight still matters |
The nut is only as good as how it stays put. A bearing locknut that backs off under vibration destroys the bearing it was holding. We machine the locking feature to your design — the tongue slot for an MB / AN tab washer, radial set screws, a nylon insert, or a wedge segment for a true zero-backlash precision locknut — and supply the matching washer in the same order so the assembly locks the way the original did.
How It Works
Send the old nut or the shaft
The seized, worn or lost nut — or the shaft thread it fits. Tell us the locking method (tab washer, set screw, wedge) if you know it.
We measure and rebuild the thread
Thread, pitch, hand, OD, height and slots measured and drawn — free of charge, no part number needed. See how we work from a sample.
You approve, we machine
Single-pointed thread, slots cut, locking feature machined in, matching tab washer made — inspected before shipping.
Reorder anytime
We keep the thread and slot data on file, so the next bearing service is a one-line email at a lower unit price.
Who Orders Custom Lock Nuts
"The bearing came with a locknut in a size I can't source, and the machine's down"
Send the old nut or the shaft. We reproduce the KM/AN nut and its tab washer to fit, in days — so the bearing job isn't held up by a locknut nobody stocks in that thread.
"This spindle's adjusting nut is obsolete and I need the preload exactly right"
We copy the obsolete nut — thread, slots and locking — and can add height for more engagement or a wedge lock for zero backlash, so the rebuilt spindle holds preload like new.
"My design uses a non-standard fine pitch and there's no catalogue nut for it"
We single-point the nut to your pitch — left-hand, extra-fine, whatever the shaft needs — with your slot pattern and locking feature, repeatable from saved data with material certs.
"I need the same locknut but lighter, and in the exact thread on my shaft"
We machine it in 6061 or 7075 aluminium to the exact thread and preload feature — light, precise, and made one-off if that's all you need.
What Buyers Search For
Frequently Asked Questions
Yes — that is the usual reason to have one machined. The KM/AN series stops at set sizes and pitches; when your shaft thread falls outside it, or you need a diameter or height the catalogue doesn't list, we machine the round slotted nut to your exact thread, OD, height and slot pattern so a standard hook spanner still fits.
Yes. Send the old nut — even seized or partly stripped — or the shaft it threads onto, and we measure the thread, pitch, slots and locking feature and reproduce it. No part number or drawing needed; we work from the physical part.
No. Left-hand, extra-fine, and non-standard pitches are routine on machine spindles and adjusting nuts. Tell us the pitch and hand, or send the shaft, and we single-point the thread to match — including odd pitches no tap or die exists for.
Yes. We make the matching MB / AN tab washer, tongued or slotted, in the same order so the assembly locks the way it should. If your design uses set screws, a nylon insert or a wedge segment instead, we machine that locking feature into the nut itself.
Standard is medium-carbon or alloy steel for strength and thread wear; 303/304/316 stainless for corrosive, washdown or marine service; brass where a softer nut protects the shaft. For lightweight spindles — motorsport and aerospace — we machine them in 6061-T6 or 7075-T6 aluminium. All cut from solid with EN 10204 3.1 certificates on request.
Yes. Extra height for more thread engagement, a larger OD for spanner clearance, deeper or extra slots, or a heavier wall for high preload — all machined to your requirement. Tell us the load or preload and we advise on height and material.
Related Custom Fasteners
Bearing and spindle nuts often ship with their neighbours. We also machine castle & slotted nuts to DIN 935, coupling nuts including reducing and LH/RH, and any non-standard thread bolts to match. For the shaft side of a bearing rebuild see pump replacement parts, and if the bearing itself is obsolete we can reverse engineer a bearing from a worn part. For anything truly one-off, special fasteners made to drawing.
Lock Nut Quote
Send the old nut or the shaft thread. Reply in 24h.
// Qty & price
1 pc
Sample price
Confirm fit before a run
3–10
Unit price drops
Setup cost shared
10+
Best price
All tiers quoted upfront
- →No distributor — you pay the maker directly
- →Thread & slot data saved — reorder anytime at lower unit price