Machine Screw Anchor
Anchors · expansion shield · lead anchor · machine screw anchor
Definition: A machine screw anchor is a metal expansion sleeve that a machine screw threads into, expanding the sleeve to grip masonry.
Anatomy
■ Head■ Shank■ Threads■ Point
Governing standards: Manufacturer specified (no universal standard)
Common Sizes
| Inch | Metric | Head width | Head height |
|---|---|---|---|
| for #8 | M4 | — | — |
| for 1/4 | M6 | — | — |
| for 5/16 | M8 | — | — |
Representative sizes. Full dimensional data lives in the standards listed below.
Grades & Strength
| Grade | Material | Tensile (psi) | Marking |
|---|---|---|---|
| Zinc alloy | zinc | — | None |
| Steel / stainless / lead | varies | — | None |
Materials
- Zinc alloy
- Steel
- Stainless steel
- Lead
Pros & Cons
Pros
- Removable screw
- Holds in block and brick
- Inexpensive
Cons
- Needs the right hole size
- Sleeve stays behind
- Lower strength than wedge anchors
Typical Uses
- Concrete and block walls
- Handrails
- Conduit straps
- Light-to-medium fixtures
Alternatives & Related
- Sleeve Anchor — Stud-style anchor with a nut for heavier loads
- Lag Shield — Expanding shield for a lag screw
- Concrete Screw — Screws directly into masonry with no sleeve
Where to Buy
Affiliate links — we may earn a commission at no cost to you.
FAQ
What is a machine screw anchor?
A metal sleeve you tap into a drilled hole; driving a machine screw expands it against the masonry to hold a fixture.
Machine screw anchor vs sleeve anchor?
A machine screw anchor takes a separate machine screw; a sleeve anchor is a complete stud-and-nut assembly for heavier loads.