When a Bolt Outgrows the Hardware Aisle
Below M20, bolts are a commodity. Above it, the shelves thin out fast: an M30×2 in a 400 mm length, an M42 with a square head, a 2½" UNC stud for a fifty-year-old press — these aren't stock items anywhere. Distributors quote long waits and high minimums because someone upstream has to make the part anyway.
We are that someone, minus the middle step. EKINSUN turns large bolts directly from certified bar on CNC lathes — thread, head and shank machined to your drawing or measured from your broken original.
Machined or Forged? An Honest Answer
Big bolts come from two worlds, and the right one depends on your job:
| Hot-forged (a forge house) | Machined from bar (us) | |
|---|---|---|
| Best at | High-volume structural hardware — towers, bridges, steel erection | Singles to a few hundred; specials; replacements |
| Tooling | Heading dies — economical only at volume | None — geometry is a CNC program |
| Geometry | Standard heads and grades | Any head, shank step, shoulder, drilled feature, thread combination |
| Lead time at qty 1–50 | Often quoted in months, if at all | Days to a few weeks |
Need 5,000 standard A325 structural bolts? Go to a forge — genuinely. Need one M36 replacement or fifty M48 tie bolts with a machined shoulder? That job was designed for a lathe.
The Jobs That Land on Our Bench
"The M42 tie bolt on our press sheared. OEM says 14 weeks."
Send both halves — together they carry the full geometry. We measure thread, grip length and head, machine from 42CrMo4 with a 3.1 certificate, and typically ship in a fraction of an OEM lead time. Order a spare in the same run; the second piece costs far less than the first.
"Crusher and mill anchor bolts in odd lengths — nobody stocks them."
Long anchor and foundation bolts to your exact length and thread projection, with square or heavy hex heads, bent J/L forms excepted — straight machined forms are our territory, delivered with matching nuts and thick washers.
"Big stainless bolts with an obsolete thread on a shaft coupling."
A4-80 and duplex machined to the original spec — including pre-metric and imperial threads (BSW, UNC 2½"+) that modern catalogs dropped decades ago. We gauge the old thread and match it, not approximate it.
Materials, Classes & Certificates
| Material | Class / grade | Typical use |
|---|---|---|
| Carbon steel C45 | ~8.8 equivalent | General machine bolts, base plates |
| Alloy 42CrMo4 (1.7225) | 10.9 / ASTM B7 equivalent | Press tie bolts, high-load joints — quenched & tempered |
| Stainless A2-70 (304) | 70 | General corrosion resistance |
| Stainless A4-80 (316L) | 80 | Marine, chemical, washdown |
| Duplex / super duplex | per spec | Offshore and aggressive media |
- EN 10204 3.1 material certificate traceable to bar heat, on request
- Hardness and tensile testing for critical joints
- Thread gauging to ISO 965 6g (or the imperial class your drawing calls)
- Finishes: plain, black oxide, zinc, hot-dip galvanized via partner, passivated stainless
Matched sets: large or non-standard nuts and thick washers are machined in the same material and finish, so the whole joint arrives as one certified package — no hunting a second supplier for an M64 nut.
Frequently Asked Questions
Up to roughly M100 (4") diameter and past 1000 mm long, turned from solid bar. Above that, or for forged heads on structural volume, a forging house is the right supplier — and we'll say so.
Forging wins on cost at high volume in standard grades. Machining wins for 1–500 pieces, non-standard geometry, exact lengths, unusual materials, and replacements nobody stocks — no die, no tooling charge, no minimum.
Yes — EN 10204 3.1 certificates traceable to the bar heat, plus dimensional and hardness reports on request. Critical bolts are machined from certified 42CrMo4, class 8.8/10.9 steel, A4-80 or duplex bar.
Yes — a typical order. Send the broken bolt (both halves) or the dimensions; we confirm the drawing with you and machine the replacement, usually far inside the OEM lead time.
Yes — large hex, round or castellated nuts and thick washers in the same material and finish, delivered as a matched, certified set.
Get Large Bolts Quoted
Drawing, dimensions or the broken bolt. Engineers reply in 24h.
// Qty & price
1 pc
Sample price
Confirm fit before a run
3–50
Unit price drops
Setup cost shared
50+
Best price
All tiers quoted upfront
- →No distributor — you pay the maker directly
- →CAD saved after first order — reorder anytime at lower unit price