Reference illustration — produced to your drawing
Screws
Lag Screws
A lag screw, or lag bolt, is a heavy-duty fastener with a hex head and a coarse tapered thread that bites deep into timber. It is driven with a wrench, not a screwdriver, for high clamping force.
It joins heavy timber, beams, decks and ledger boards where a wood screw is too small. Timber frame builders and structural carpenters use it for load-bearing wood connections.
Standard
ASME B18.2.1
Size range
M6 – M20 · 1/4 – 3/4 in
MOQ
From 50 pcs
Lead time
Samples 5–10 days
What we produce
- Hex head driven with a wrench
- Coarse thread for deep timber grip
- Carbon steel 1045 or stainless 304 / 316L
- Hot-dip galvanized for exterior timber
- Washer face spreads load under the head
Specification notes
- Sizes M6 to M20 and 1/4 in to 3/4 in
- Common lengths 20 mm to 250 mm
- Pilot hole size stated with each size
Specifications
Every line below is a starting point, not a limit. Non-standard sizes, special threads and unusual materials are what we do — send the drawing and we confirm what fits.
| Standard | ASME B18.2.1 |
|---|---|
| Size range | M6 – M20 · 1/4 – 3/4 in |
| Threads | Coarse wood thread · UNC |
| Head / geometry | Hex head with washer face; hex socket or hex wrench drive |
| Materials | Stainless steel 301 / 303 / 304 / 304L / 316 / 316L / 410 / 416 / 17-4PH · carbon steel 1045 / 1215 / 12L14 · alloy steel 4130 / 4140 · aluminium 2024 / 5052 / 6061 / 7075 · brass · bronze · copper · titanium |
| Finishes | As machined · black oxide · zinc plating · nickel plating · chrome plating · anodizing · passivation (through our vetted partner network) |
| Precision | ±0.01 mm on features that locate, seal or fit; ISO 2768-m for general dimensions |
| Marking | Head marking, grade marking or your own identification mark per drawing |
| Documents | Material certificate (MTR) with every batch, plus pre-shipment photos before dispatch |
| MOQ | From 50 pieces per type and material · samples from 1 piece |
| Sample lead time | 5–10 days |
| Production lead time | 25–35 days after sample approval |
| Quote | Within 24 hours, with DFM feedback |
Other screws we manufacture
See all 179 part types →
Send us the drawing
We reply within 24 hours with DFM feedback, a process route and a price. Samples from 1 piece, production from 50 pieces, shipped from Qidong City, Jiangsu Province, China.
Request a quote