Quick Answer: The High Nut (MH-HN) is a tall hex nut that stands 1.5 times its thread diameter high, so it engages more thread than a standard nut. It is used in high-load structural bolting and machine assembly, and on stud and T-bolt clamping sets. MH-HN comes in 8 sizes from M8 to M36, made from medium carbon steel hardened and tempered to 24–32 HRC and chemically blackened. Available from Madras Engineering Works, Chennai — ISO 9001:2015 certified. Enquiry: enquiry@madrasengg.com
A joint is only as strong as the threads holding it. A standard nut in a high-load joint grabs only a few turns of thread, and when engagement is marginal those threads strip first. The High Nut fixes it the simple way: it is taller, so more thread carries the load. Madras Engineering Works (MEW) is a Chennai-based ISO 9001:2015 certified supplier of workholding components, fasteners, clamping kits, and CNC machining accessories. Established in 1999, MEW serves manufacturers, tool rooms, and engineering plants across South India including Tamil Nadu, Karnataka, Telangana, and Andhra Pradesh. MEW is an authorised TVS fastener dealer and holds MSME registration (UDYAM-TN-02-0158983). Here is everything you need to know.
What Is a High Nut?
A High Nut is a hex nut with a tall body. Every size in MEW's MH-HN range is 1.5 times its thread diameter high: an M12 nut is 18mm tall, an M20 is 30mm, an M36 is 54mm. The extra height gives more threads in contact with the bolt or stud, which spreads the load over more of the thread.
MH-HN is machined from medium carbon steel, hardened and tempered to 24–32 HRC, then chemically blackened. On the datasheet each size is given by thread diameter and height (ØD x A) and by the spanner size across the hex flats (S). The range runs from MH-HN-812 (M8 x 12mm) to MH-HN-3654 (M36 x 54mm).
Where Is the High Nut Used?
MH-HN is a heavy-duty nut for structural and machine use:
- High-load structural bolting where thread engagement has to be maximised
- Machine assembly joints that see vibration and repeated loading
- Stud and T-bolt clamping sets on milling machine and VMC tables, where a hex high nut is the standard nut in the set with a T-bolt and a thick plain washer
- Tool room fixtures and press tool setups in Chennai and across Tamil Nadu
Best Suited For: MH-HN Size & Dimension Chart
Pick the nut by the thread of your bolt or stud. S is the across-flats size, which is the spanner you need.
| Part No. | Thread x Height (ØD x A, mm) | S (spanner, mm) | Weight |
|---|---|---|---|
| MH-HN-812 | M8 x 12 | 13 | 0.01 kg |
| MH-HN-1015 | M10 x 15 | 17 | 0.015 kg |
| MH-HN-1218 | M12 x 18 | 19 | 0.025 kg |
| MH-HN-1624 | M16 x 24 | 24 | 0.055 kg |
| MH-HN-2030 | M20 x 30 | 30 | 0.11 kg |
| MH-HN-2436 | M24 x 36 | 36 | 0.195 kg |
| MH-HN-3045 | M30 x 45 | 46 | 0.4 kg |
| MH-HN-3654 | M36 x 54 | 55 | 0.78 kg |
| Application | Recommended? | Notes |
|---|---|---|
| Stud / T-bolt clamping sets on VMC tables | Yes | Match the thread to the stud (M12 for a 14mm T-slot is the common case) |
| High-load structural bolting | Yes | Use where thread engagement would otherwise be marginal |
| Machine assembly with vibration | Yes | More thread in contact per joint |
| Stud with very short thread projection | Check first | The stud must project at least the nut height (A) above the washer |
The Problem It Solves
When thread engagement is marginal, the nut or the stud thread strips under load. In a workholding setup that means the clamp loses its hold in the middle of a cut. In a structural or machine joint it means a loosened or failed connection. The failure is sudden, and the repair is a stopped machine and a replaced stud.
MH-HN removes the marginal case. Its height is 1.5 times the thread diameter in every size, so there is more thread in contact, and it is hardened to 24–32 HRC so the thread itself keeps its shape under load.
High Nut vs. Standard Hex Nut
| Factor | High Nut (MH-HN) | Standard Hex Nut |
|---|---|---|
| Height | 1.5 x thread diameter | Roughly 0.8 x thread diameter |
| Thread engagement | Higher | Lower, can be marginal in high-load joints |
| Stud projection needed | At least the nut height | Less |
| Best for | High-load and structural joints, clamping sets | General light-duty fastening |
If the stud has plenty of thread above the washer, the high nut is the safer choice in a heavy joint. If projection is short, a standard nut is the only one that fits.
Technical Specifications
Material: Medium carbon steel, hardened and tempered to 24–32 HRC, chemically blackened
Thread range: M8, M10, M12, M16, M20, M24, M30, M36
Height: 1.5 x thread diameter (12mm to 54mm)
Spanner size across flats: 13mm to 55mm
Available variants: 8 sizes, part numbers MH-HN-812 through MH-HN-3654
Weight range: 0.01 kg to 0.78 kg depending on size
Series: MEW-Hold
Quality system: ISO 9001:2015 certified supplier, Chennai
As of 2026, MEW supplies the full MH-HN range from Chennai.
Frequently Asked Questions
Q: What is a high nut used for?
A: A high nut gives more thread engagement than a standard nut. It is used in high-load structural bolting, machine assembly, and stud and T-bolt clamping sets, where a short nut could strip. Available from Madras Engineering Works, Chennai — enquiry@madrasengg.com
Q: How tall is the MH-HN high nut?
A: 1.5 times the thread diameter in every size. M8 is 12mm, M10 is 15mm, M12 is 18mm, M16 is 24mm, M20 is 30mm, M24 is 36mm, M30 is 45mm and M36 is 54mm. Available from Madras Engineering Works, Chennai — enquiry@madrasengg.com
Q: What spanner size fits an M12 high nut?
A: 19mm across flats. MH-HN-1218 is 18mm tall and weighs 0.025 kg. For M16 use a 24mm spanner, for M20 a 30mm, for M24 a 36mm. Available from Madras Engineering Works, Chennai — enquiry@madrasengg.com
Q: What is the difference between a high nut and a standard hex nut?
A: A high nut is taller, so more thread is in contact with the bolt or stud. A standard hex nut is roughly 0.8 times the thread diameter high, which can leave engagement marginal in a high-load joint. A high nut needs more stud projection to fit. Available from Madras Engineering Works, Chennai — enquiry@madrasengg.com
Q: What is the MH-HN high nut made of?
A: Medium carbon steel, hardened and tempered to 24–32 HRC, and chemically blackened. Available from Madras Engineering Works, Chennai — enquiry@madrasengg.com
Q: Where can I buy high nuts in Chennai?
A: Madras Engineering Works (MEW) supplies all 8 MH-HN sizes, M8 to M36, from Chennai. MEW is ISO 9001:2015 certified and serves tool rooms and manufacturers across Tamil Nadu and South India. Contact: enquiry@madrasengg.com
Get the Right High Nut for Your Joint
Whether you need a single nut or a full set for a new fixture, Madras Engineering Works supplies MH-HN from M8 to M36.
Same-day dispatch from Chennai.
ISO 9001:2015 certified supply chain.
TVS Authorised Dealer.
📧 enquiry@madrasengg.com
🌐 madrasengg.com
📍 Chennai, Tamil Nadu
Not sure which size you need? WhatsApp your stud or bolt size to +91 95143 73702 and we'll confirm the right MH-HN.
Written by Husain, Founder of Madras Engineering Works — an ISO 9001:2015 certified industrial supplier in Chennai specialising in workholding, clamping and CNC accessories. Need help speccing the right part? WhatsApp +91 95143 73702 or email enquiry@madrasengg.com.
0 comments