How to find the right Flat Washers AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Flat Washers
- Pattern: SAE, USS or fender
- SAE washers have a smaller OD and fit close. USS washers are larger and thicker for wood and general construction. Fender washers have a very large OD for thin or soft material. The same bolt size comes in very different ODs, and that sets pull-through resistance.
- Hardness for bolt grade
- Use through-hardened washers with Grade 8 or Class 10.9 bolts. Use ASTM F436 washers with structural bolts. Soft washers dish and lose clamp load under high-strength bolts.
- Metric standard
- For metric bolts, buy to ISO 7089 or DIN 125. The standard guarantees the hole and OD fit the metric bolt size.
- Material and coating
- Use 18-8 stainless for general rust resistance and 316 for salt. Use hot-dip galvanized with galvanized bolts and treated lumber. Washers that don't match the bolt corrode at the joint.
Brands that matter
- Hillman: Widely stocked SAE, USS and fender washers.
- Bolt Dropper: Bulk stainless and zinc packs.
- Simpson Strong-Tie: Washers for treated-lumber and structural connections.
What to avoid
- Zinc-plated washers in treated lumber or outdoors
- Fender washers under high-torque bolts, because they bend
Questions
What is the difference between SAE and USS washers?
For the same bolt size, USS washers are wider and thicker. SAE washers are narrower and suit machinery and tighter spaces.