Truss Head Machine Screws are selected when an assembly calls for fixings into thin sheet, board and soft material that need the widest possible bearing head at the lowest possible profile. This application guide to the ASME B18.6.3 type covers concrete end-uses, the specification checklist, correct installation, and where an alternative fastener performs better. Stocked across roughly 1 to 10, they cover general to heavy-duty work.
Typical Applications for Truss Head Machine Screws
The most common settings where these are specified:
- Maintenance & repair (MRO): a stocked size for servicing existing plant where the original fastener spec must be matched.
- Fabrication & metalwork: bench and on-site assembly of steel frames, enclosures and weldments.
- Electronics & enclosures: mounting PCBs, panels and lids where the drive style and head height matter.
- Appliances & consumer goods: high-volume assembly with power tools and consistent seating.
- Machine guarding & panels: removable access covers that are opened for service.
How to Specify Truss Head Machine Screws for Your Application
- Size: Match the nominal size to the mating thread or hole. This product spans 1–10; check the full table below for the exact dimensions of each size.
- Drive & head: Pick the drive (socket, cross, slot) and head style for the tool access and seating surface; a recessed drive resists cam-out under power tools.
- Environment: For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
- Standard: This product is supplied to ASME B18.6.3. Quoting the standard on your order guarantees interchangeable dimensions between suppliers.
Installation & Assembly Practice
- Match the driver exactly to the recess (PH ≠ PZ; hex key sizes per ISO 2936) and keep the tool axial — side load is the main cause of stripped drives.
- In tapped holes, engage a thread length of at least 1× the nominal diameter in steel, 2× in aluminum.
- Set power tools to a torque that seats the head without embedding it into the mating surface.
Common Selection Mistakes with Truss Head Machine Screws
- Under-sizing the drive for the installation torque — a small recess at high torque strips before the screw is seated.
- Using a countersunk head in thin sheet where the countersink removes most of the load-bearing material.
- Specifying stainless in high-strength duty: A2-70 is roughly class 7 steel, not a 10.9 substitute.
Where Truss Head Machine Screws Are Not the Right Choice
Not for high-preload structural joints (use a property-class bolt and nut), and not in thin sheet where a self-drilling or self-tapping type suits better.
Custom manufacturing · Made to drawing
Need a truss head machine screws outside the standard range?
Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
