Get unique, complex parts easily. No matter your requirements, Master Spring creates hard-to-produce coil springs and wire forms.

Custom Wire Forms

Let us help you create the custom wire form you need, from S-hooks and J-hooks to utility hooks and more.


We work closely with customers across a wide range of industries, helping them design and manufacture made-to-order parts.

Master Spring Advantage

Why choose Master Spring? We prioritize customer-focused collaboration, modern equipment and the latest technology to make your parts per print.

Custom Wire Form Technical Design Resources

Explore the information below to find technical advice on wire forms, including how to specify dimensions for your wire form, how to calculate the radius of a wire form, and what ranges of wire diameter can be formed.

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Wire Form Dimensions

Wire Form Dimensions

The diagram and notes describe how to specify dimensions for wire forms. We have shown our preferred ways to specify dimensions to make it easier to inspect and produce your part.

Please refer to the legend below in regards to the wire form dimensions diagram:

  1. Bend segment drawn from edge of cut-off to theoretical corner of outside edges.
  2. Bend segment drawn from inside theoretical corner to inside edge of perpendicular bend.
  3. Bend segment drawn from inside edge of perpendicular bend to inside theoretical corner of inside edges.
  4. Inside angle.
  5. Inside diameter.
  6. Length from edge of cut-off to center of inside diameter.
    • The accumulated variation of the overall length (F) will be larger than the variation of any one dimension that makes up that overall length. A dimension like (F) that is made up of a series of bends and feed segments should be a referenced dimension. If a tolerance on an overall dimension is required, it will have to be determined after a production run.
  7. Bend radius drawn to the inside edge of the bend.
    • For low carbon (low tensile steel), we will use a bending pin with a diameter that equals 1.5X the wire diameter. So the inside radius of the bend will equal 0.75X the wire diameter.
    • For harder spring tempered steel, we will use a bending pin with a diameter that equals 2X the wire diameter. So the inside radius of the bend will equal 1X the wire diameter.
  8. Wire Diameter.


Wire Diameter Range and Wire Material Type

Wire Diameter

Specializing in building long-term partnerships with OEMs, Master Spring & Wire Form Co. has the expertise and latest equipment to manufacture the difficult or “impossible to make” wire forms. We have a wide range of CNC wire forming machines that can manufacture custom wire forms with diameters as small as 0.010″ or as large as 0.500″ (0.25mm to 12.7mm) and any size wire in between.

Wire Form Material Type

We manufacture custom wire forms from all types of material. The most common material types for wire forms are cold rolled steel (1008 or 1010 basic wire), stainless steel (type 302, type 304, type 316 or type 17-7 PH), music wire, hard drawn and oil tempered. You can learn about the suitable uses of each material type in our Properties of Materials chart.

Common Extension Spring Materials Include:

  • High Carbon Spring Wire
  • Carbon and Alloy Wire
  • Hard Drawn Wire
  • Alloy Steel Wire
  • Stainless Steel Wire
  • Non-ferrous Alloy Wire
  • And Many More!
Download Properties of Materials Guide
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Need a custom wire form or coil spring? We make it work. Fill out the contact form and a representative will respond within 1 business day. Please attach a PDF or CAD file with your request to quote.


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Your Team For Innovative Wire Forming

We provide solutions for complex, high-quality
wire forms and coil springs.

78 Congress Circle West, Roselle, IL 60172

P: 708.453.2570 | Contact Us

We do not stock standard springs,
we make made-to-order custom springs.