M1.7 Washer Dimensions & Size

Q: What does the “M1.7” designation mean on a washer?

The “M” stands for Metric, and the number represents the nominal thread diameter of the screw or bolt the washer is intended to fit. For example, an M1.7 washer is designed specifically for fasteners with a 1.7 mm nominal major diameter.

Q: What does the HV rating mean on a washer?

HV stands for Vickers Hardness. It is a measurement of the material’s resistance to indentation and deformation. For M1.7 fasteners, a rating of 200 HV or 300 HV ensures the washer does not “cup” or collapse when the bolt is tightened to its required torque.

Q: What is the difference between Form A and Form B washers?

The primary difference lies in the edge finish. Form A washers are standard flat washers with a square edge and no chamfer. Form B washers feature a 30° to 40° chamfer (a beveled or sloped edge) on one outer side, according to DIN 125B and ISO 7090 standards.

Q: Which standard governs M1.7 washers?

M1.7 washers are generally standardized under the Normal Series. The most common technical specifications for this size are found in DIN 125A (for flat washers) or ISO 7089. Unlike sizes like M1.6 or M2, a dedicated “Small Series” (DIN 433) is less common for the M1.7 designation.

M1.7 washer dimensions are standardized for high-precision applications, including optical engineering for eyewear, horology, medical diagnostics, and micro-mechanical assemblies. Specifically designed for fasteners with a 1.7 mm nominal diameter, these components ensure stable load distribution and protect mating surfaces from damage during tightening. This chart covers Form A plain washers, which feature a flat surface without a chamfer (unlike Form B). M1.7 is primarily standardized under the Normal Series. Consequently, this chart is based on the DIN 125A / ISO 7089 standards. Based on these standards, M1.7 washers typically feature a hardness of 200 HV or 300 HV (Vickers Hardness), providing the necessary structural integrity to prevent deformation under the clamping force of high-tensile bolts used in smartphones and precision sensors.

Note: While these values reflect standard manufacturer datasheets, actual dimensions and tolerances may vary based on material (e.g., Stainless Steel vs. Nylon) and manufacturing class. Always verify with the official product datasheet for critical applications.

Washer dimension diagram showing inner diameter, outside diameter, and thickness

M1.7 Standard Series Washer – DIN 125A/ISO 7089
Dimension	Size (mm)
Dimension	Min	Max
Inner Diameter	1.8	1.94
Outside Diameter	4.2	4.5
Thickness	0.25	0.35

Inner Diameter – The diameter of the hole, designed to clear the bolt/screw thread.
Outside Diameter – The total width of the washer, determining the load distribution area.
Thickness – The height of the washer, providing the spacing and structural support.

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Frequently Asked Questions

What does the “M1.7” designation mean on a washer?

The “M” stands for Metric, and the number represents the nominal thread diameter of the screw or bolt the washer is intended to fit. For example, an M1.7 washer is designed specifically for fasteners with a 1.7 mm nominal major diameter.

What does the HV rating mean on a washer?

HV stands for Vickers Hardness. It is a measurement of the material’s resistance to indentation and deformation. For M1.7 fasteners, a rating of 200 HV or 300 HV ensures the washer does not “cup” or collapse when the bolt is tightened to its required torque.

What is the difference between Form A and Form B washers?

The primary difference lies in the edge finish. Form A washers are standard flat washers with a square edge and no chamfer. Form B washers feature a 30° to 40° chamfer (a beveled or sloped edge) on one outer side, according to DIN 125B and ISO 7090 standards.

Which standard governs M1.7 washers?

M1.7 washers are generally standardized under the Normal Series. The most common technical specifications for this size are found in DIN 125A (for flat washers) or ISO 7089. Unlike sizes like M1.6 or M2, a dedicated “Small Series” (DIN 433) is less common for the M1.7 designation.

In which materials are these washers commonly available?

Metric washers in this size are most frequently produced in A2 (304) or A4 (316) Stainless Steel. They are also available in Zinc-Plated Steel and Brass for specific industrial or electronic applications.