Brass Round Bar Grade CZ121 | 12.7mm (1/2") Diameter x 270mm | Model Making & Engineering

A single length of Grade CZ121 free-cutting brass round bar, 12.7mm (1/2") diameter x 270mm (approx. 10.5") long. CZ121 is the most widely used free-machining brass alloy in the UK, offering excellent machinability, corrosion resistance, and a clean golden finish — suitable for a broad range of engineering, hobby, and manufacturing applications.

Who Is This For?

Ideal for model makers, engineers, machinists, and hobbyists working on components requiring a larger cross-section. At 12.7mm (the imperial 1/2" equivalent), this is the largest of the three bar diameters available and is well suited to heavier-duty turned parts, bushes, flanges, and fittings where more material is needed. Suitable for professional and home workshop use.

Key Features

• Grade CZ121 Free-Cutting Brass: The standard free-machining brass grade in the UK. The lead content acts as a lubricant and chip-breaker during machining, giving smooth, consistent results and extended tool life.
• 12.7mm (1/2") Diameter x 270mm Length: The largest diameter in this range — suited to heavier components, larger bushes, flanges, and parts requiring more material volume.
• Corrosion Resistant: Brass alloy provides excellent resistance to corrosion in air, water, and many chemicals — suitable for indoor and outdoor applications.
• Attractive Golden Finish: Clean, bright finish straight from stock — suitable for decorative and functional applications.
• Virgin Material: Made from new, unrecycled brass stock for consistent composition and maximum strength.
• Easily Worked: Can be machined, turned, drilled, sawn, filed, soldered, and brazed using standard workshop tools and techniques.

Specifications

• Grade: CZ121 (free-cutting brass)
• Diameter: 12.7mm (1/2")
• Length: 270mm (approx. 10.5")
• Form: Round bar / rod
• Finish: Bright
• Material: Brass alloy (copper-zinc with lead)

Frequently Asked Questions

What is CZ121 brass? CZ121 is the British Standard designation for free-cutting brass — a copper-zinc alloy with a small lead addition. The lead content makes it highly machinable by acting as a built-in lubricant and chip-breaker during cutting operations. It is the most commonly specified brass grade for precision turned parts in the UK.

What can I make from a 12.7mm brass round bar? Common applications include larger bushes, flanges, standoffs, couplings, model engineering components, decorative fittings, electrical contacts, and any component requiring a 1/2" cross-section. The 12.7mm diameter is also the standard imperial half-inch size, making it compatible with imperial tooling and imperial-dimensioned designs.

Can I cut this bar to length at home? Yes. CZ121 brass can be cut using a hacksaw, metal-cutting bandsaw, or angle grinder with a metal disc. At 12.7mm diameter, a larger hacksaw or power tool is recommended for a clean, square cut.

How does 12.7mm compare to the 8mm and 10mm versions? The 12.7mm bar is the largest of the three diameters available. Choose 12.7mm when more material volume is needed for heavier or larger components. The 10mm is a general-purpose mid-range size, and the 8mm is the slimmest option for fine precision work.