Screws by material

What the second piece is made of decides the thread. This is the catalogue grouped that way.

Particleboard & MDF

Soft, uniform cores that crumble if a thread does not have enough to hold on to.

What is in this group: Deep and twinfast threads — a taller thread with more space between the turns, so it packs the core rather than chewing it.

Plywood

Alternating grain and glue lines: harder than particleboard, softer than solid stock.

What is in this group: Deep or coarse thread, depending on the ply and how close to an edge you are working.

Hardwood

Solid stock, where the risk is splitting the workpiece rather than stripping the hole.

What is in this group: Coarse and fine threads — a shallower thread that cuts cleanly into dense timber instead of wedging it apart.

Thread choice is the rule of thumb, not the whole answer — point type and pilot hole matter too, especially near an edge. If a joint is marginal, call (812) 639-0120.