CNC Turned Custom Steel and Brass Prototype Bolts

These are custom prototype bolts, screws and studs CNC turned and milled to a 3D model or drawing. Materials include carbon and alloy steel equivalent to property classes 4.8 to 12.9, stainless steel, brass and engineering plastics. They are made for automotive and machinery engineers who need non-standard heads, shanks or threads before committing to cold-heading tooling.

Material: Carbon Steel
Tolerance: to ±0.005 mm
MOQ: 1 piece
Prototype lead time: 3–7 days

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Any head, shank or thread shape from bar stock
Steel equivalent to classes 4.8 to 12.9
Stainless, brass, nylon and PEEK options
Thread gauges and hardness checks available

ISO 9001 quality system, 100% critical-dimension inspection

NDA on request; your drawings are never shared

Door-to-door shipping with export documents

Item ref. 1601225790230 ·

Specifications
Process	CNC turning, thread cutting or rolling, CNC milling, broaching
Materials	Carbon/alloy steel (4.8–12.9 equivalent), stainless steel 304/316, brass, nylon, PEEK
Tolerance	±0.05 mm standard; down to ±0.005 mm on critical features
Surface Finish	Zinc plating, black oxide, passivation, nickel plating
Strength Classes	4.8 / 8.8 / 10.9 / 12.9 equivalent
MOQ	1 piece; prototypes through mid-volume
Drawing Formats	STEP, IGES, X_T, STL, DWG, DXF, PDF
Lead Time	Prototypes typically 3–7 working days; production 10–20
Inspection	First-article, in-process and CMM checks; reports on request

Manufacturing

How we make this part

Process, material options and inspection for cnc turned custom steel and brass prototype bolts.

Production bolts are cold headed, but that requires dies. For prototypes, we turn bolts from bar: the head diameter, shank and thread are turned, and the head drive (hex, socket, Torx-style or slotted) is milled or broached. Threads can be single-point cut for unusual pitches or rolled on standard sizes. This method makes almost any bolt shape possible in small quantities.

Strength class depends on material and heat treatment: low-carbon steel corresponds to class 4.8, medium-carbon or alloy steel heat treated to 8.8, 10.9 or 12.9. Note that machined heads lack the grain flow of a forged head, so fatigue performance may differ from production bolts. 304 or 316 stainless, brass and nylon or PEEK cover corrosion, conductivity and insulation needs.

Thread fit is checked with go/no-go gauges, head height and shank diameter with micrometers, and heat-treatment reports record hardness for hardened bolts. Every prototype batch is inspected on critical features, and material certificates are available on request. Typical uses include automotive prototype fasteners, special-length shoulder screws, tamper-resistant drive screws, brass terminal screws and insulated plastic bolts.

FAQ

Frequently asked questions

Is a machined prototype bolt as strong as a production bolt?

Static strength can match if material and heat treatment match. Fatigue strength may be lower, because machining cuts across the grain under the head while cold heading forms it. For load tests, ask for rolled threads and generous head-to-shank fillets to narrow the gap.

Can you make bolts with non-standard thread pitches?

Yes. Single-point thread turning can cut almost any metric, unified or special pitch, including left-hand threads and multi-start forms. Send the thread specification or a mating part, and we will confirm the thread class and gauge method before production.

How do I get a quote for cnc turned custom steel and brass prototype bolts?

Send a 3D model (STEP or IGES) and a 2D drawing with tolerances, material, finish and quantity through the quote form or by email. An engineer replies within 24 hours on business days with price, lead time and any DFM suggestions.