Spherical Washer Sets

When the bearing surface under a nut is not square to the bolt, a flat washer only touches on one edge. That bends the bolt, loads the threads unevenly and makes the preload hard to control.

In a spherical washer set, the convex face of the spherical washer sits in the cone of the seat washer. As the nut is tightened the spherical washer rotates in the seat until the nut face is square to the bolt axis, so the load is spread evenly around the bearing face. The set corrects small angles only; it is not a substitute for a properly machined seat.

• Type C, spherical washer: flat on one face, convex spherical on the other. Fits under the nut or bolt head.
• Type D, conical seat: flat on the bottom with a cone on top that receives the spherical washer. The bore is larger than the bolt so the set can tilt.
• Type G, conical seat: a deeper conical seat with a larger bore, for use where more clearance around the bolt is needed.
• Custom sets: special bores, outside diameters, heights or materials made to your drawing.

• Fixtures, jigs and machine tool clamping
• Press, die set and tooling bolts
• Machine bases, pedestals and equipment leveling
• Load cells, test frames and instrumentation mounts
• Bolting on cast, forged or out-of-square surfaces

We supply spherical washer sets in carbon, alloy, stainless and nickel grades. Match the set to the bolt and nut, especially in corrosive or high-temperature service. Compare alloys in our Fastener Materials Matrix.

Finishes include plain, zinc electroplated and zinc-nickel, or as specified. Mill test reports come with every order.

To quote spherical washer sets, tell us:

• Bolt size and the standard (for example DIN 6319), or send a drawing.
• Seat type: Type D, Type G or custom.
• Material and grade, and any finish.
• Quantity and whether you also need the studs, bolts or nuts.

What is a spherical washer set?

A pair of washers: a spherical washer with a convex face and a conical seat washer that receives it. Together they let the nut sit square when the bearing surface is slightly out of square to the bolt.

What is the difference between Type D and Type G seats?

Both are conical seats that pair with a Type C spherical washer. Type G has a deeper cone and a larger bore than Type D, giving more clearance around the bolt.

How much misalignment can a spherical washer set correct?

Only small angles. The bore clearance in the conical seat limits how far the set can tilt, so a badly out-of-square surface should be machined instead.

Can you make custom spherical washer sets?

Yes. Custom sizes and materials can be turned on our CNC lathes to your drawing.

What materials are available?

Carbon, alloy, stainless and nickel grades, with mill test reports on every order.