Cap Head

Compare your fastener to our visual size guide to confirm M-size, pitch and length.
Match your driver bit to the screw recess - Phillips, Pozi, slot or internal hex. Our Driving range lists the bit size for every drive type we stock.
Cap head machine screws use a cylindrical head with an internal hex (Allen) socket and are fully threaded for tapped holes or a matching nut. The compact head and deep socket give a high, reliable clamp load in a small footprint, and they sit flush when used in counterbored holes.
Also known as: Socket Head Cap Screw, Allen Cap Screw, SHCS, Cap Screw.
Used across machinery, jigs and fixtures, tooling, hydraulics and general engineering assembly where a strong, low-profile fixing is needed in a tapped hole.
DRIVE TYPES
Internal hex (Allen) - driven with a hex key for high torque without cam-out. Matching keys and bits are in our Driving section.
MATERIALS
Stocked in G304 and G316 stainless and high-tensile carbon. For the full engineering-grade cap screw range (Class 12.9 and the complete size span), see our Cap Head Socket Screws category.
THREAD SYSTEMS
Available in metric coarse and fine, plus imperial (UNC/UNF and BSW) threads. Machine screws are fully threaded with a uniform diameter and need a pre-tapped hole or a matching nut - they do not cut their own thread.
WHY AUSTRALIA TRUSTS BOLT & NUT
With 15+ years selling fasteners online from Brisbane, we hold over 25,000 stock lines and 200 million pieces - 98.75% of online orders placed before 1pm leave same day. Save more as you buy more - we offer up to 13 price breaks plus 3 spend-tier discounts. Read our customer reviews or get in touch if you need help picking the right machine screw.
A cylindrical socket-drive head with an internal hex (Allen) socket - a high-clamp, low-profile machine screw that drives cleanly in counterbored holes. Stainless and high-tensile carbon, metric and imperial.
TECHNICAL RESOURCES
Key charts and specification sheets: Imperial vs Metric Strength Chart
For the full library, see our Technical PDF's Library.
















