Spacer Washer
Washers · shim washer · ground spacer · arbor shim · precision spacer washer
Definition: A spacer washer is a precision-thickness washer used to set exact gaps and preload — for shimming bearings, gears, and machine assemblies.
Anatomy
■ Body■ Hole
Governing standards: Manufacturer specified (no universal standard)
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| for 1/4 | M6 | 0.50 OD | 0.005 to 0.125 thick |
| for 1/2 | M12 | 1.00 OD | 0.010 to 0.250 thick |
| for 1 | M24 | 1.75 OD | 0.020 to 0.375 thick |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| Steel | steel | — | None |
| Stainless / brass | varies | — | None |
Materials
- Steel
- Stainless steel
- Brass
- Aluminum
Pros & Cons
Pros
- Precise thickness control
- Cheap way to adjust fit
- Ground flat and parallel
Cons
- One thickness per washer
- Easy to lose track of stack height
- Not load-bearing
Typical Uses
- Bearing preload shims
- Gear spacing
- Machine tool setup
- Automotive differentials
Alternatives & Related
- Flat Washer — General load spreading, not precision spacing
- Unthreaded Spacer — Longer sleeve for bigger gaps
Where to Buy
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FAQ
What is a spacer washer?
A precision-thickness washer for setting exact gaps and preload in bearings, gears, and machine assemblies.
Spacer washer vs flat washer?
A spacer washer has a controlled, ground thickness for precise shimming; a flat washer is a general load-spreader with loose tolerances.