Screws: what Claude and GPT would buy

Two AI models chose on their own, with no web access. Nobody tested these products: this is what each one says, and how to check it.

They disagree: Claude chooses SPAX and GPT chooses GRK Fasteners

In Industrial & Scientific, Claude and GPT choose the same brand in 52 of 107 categories.

Claude Opus 5.5 · October 28, 2026

SPAX MultiMaterial (line)

A single general-purpose screw with a self-cutting point and partial thread that drives cleanly into wood, particleboard and plastics without pilot holes in most softwoods, so one box covers most household fastening.

Not for: Anyone fastening into concrete, steel framing, drywall or structural ledgers, which each need a purpose-made screw.

GPT 6.1 Sol · November 10, 2026

GRK Fasteners R4 Multi-Purpose Screws (line)

Star-drive heads resist cam-out, while self-countersinking heads and cutting threads make these versatile screws convenient for general woodworking.

Not for: Masonry, metal-to-metal fastening, or applications requiring specific engineered fasteners.

Claude also lists GRK Fasteners among the brands that matter.

Which one fits you

outdoor decking into treated lumber

Simpson Strong-Tie Deck-Drive DSV (line)

A coated deck screw sold for use in preservative-treated lumber, with a drill point and a Torx-style drive that resists cam-out.

Not for: Coastal or poolside builds, which call for stainless steel.

Check before you buy

Match the screw to the substrate. Use wood thread for wood, fine or self-drilling thread for steel, and a masonry screw for concrete; do not cross over. Thread geometry and hardness are designed for one material, and the wrong screw strips out or snaps.
Drive type. Choose Torx (star) or square drive over Phillips for anything driven with an impact driver. Phillips is designed to cam out, which damages heads and bits under high torque.
Coating vs. exposure. Use bright or black phosphate indoors only, coated or hot-dip galvanized for treated lumber outdoors, and stainless near salt water or pools. Corrosion, not thread strength, is the most common way screws fail outdoors.
Head style. Use flat or bugle heads where they must sit flush, and pan, washer or truss heads for clamping thin material. The head determines whether a screw countersinks or bears on the surface.

Where to find SPAX MultiMaterial

Lowe's
Walmart
JMP Wood

Shops seen in search results on November 6, 2026. A shop missing here may sell it too. Nothing was checked by a person.

Brands that matter

SPAX: Multi-material wood screws with self-cutting points.
GRK: Premium construction and structural wood screws.
Simpson Strong-Tie: Deck, structural and collated screws with published code reports.
FastenMaster: Structural screws such as the LedgerLOK and TimberLOK lines.
Tapcon: The reference concrete screw.
Hillman: Broad hardware assortment covering most small-fastener types.

What to avoid

Unbranded multi-hundred-piece assortments with soft steel that strips at the drive.
Black drywall screws used for furniture or outdoor projects; they are brittle and rust.

Questions

Screw or bolt?

A screw makes or engages its own thread in the material, while a bolt passes through and is held by a nut; machine screws sit in between and need a tapped hole or a nut.

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