Step Bolt
Bolts · ladder bolt · round head square neck bolt
Definition: A step bolt has a large round head and a square neck, used to bolt ladder rungs and steps to rails — the square neck keeps it from spinning while the nut is tightened.
Anatomy
■ Head■ Shank■ Threads■ Point
Governing standards: Manufacturer specified (no universal standard)
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| 3/8-16 | M10 | 1 | 2 to 6 long |
| 1/2-13 | M12 | 1-1/4 | 3 to 8 long |
| 5/8-11 | M16 | 1-1/2 | 4 to 10 long |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| Grade 2 | low carbon steel | 74,000 | None |
| Galvanized | hot-dip galvanized steel | — | None |
Materials
- Zinc-plated steel
- Hot-dip galvanized steel
- Stainless steel
Pros & Cons
Pros
- Big smooth head — no snags
- Square neck prevents spin
- Galvanized for outdoor ladders
Cons
- Limited to step and rung work
- Head adds weight
- Overkill for general bolting
Typical Uses
- Ladder rungs
- Tank ladders
- Fixed access ladders
- Playground equipment
Alternatives & Related
- Carriage Bolt — Smaller domed head for general wood
- Hex Bolt — Standard bolting
Where to Buy
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FAQ
What is a step bolt?
A large round-head square-neck bolt for fastening ladder rungs — the smooth head faces the climber and the square neck stops rotation.
Step bolt vs carriage bolt?
A step bolt has a bigger, flatter round head for rungs; a carriage bolt has a smaller dome head for wood.