Buy Button Head Socket Screws Online in Australia
Button head socket screws combine a low, rounded dome head with an internal hex (Allen) drive — the head sits proud of the surface rather than recessing into a counterbore like a standard socket head cap screw. That makes them the go-to fastener when you want a clean, snag-free finish with good tool access, but don't need the maximum clamp load of a full cap screw. AIMS stocks metric and imperial button head socket screws from Hobson, Bremick and Inox World across Grade 10.9 and Grade 12.9 alloy steel, 304 (A2) and 316 (A4) stainless steel, and black stainless finishes — M3 to M16 in metric, and 8-32 up to 1/2" in imperial UNC. Whether you're building an enclosure, guarding machinery, or finishing a fixture where a domed head looks and sits right, we can get the right screw and drive size to your door fast. Not sure which one suits your job? Our Button Head Socket Screw Guide covers selection in detail.
Quick Reference — Grade, Finish & Drive Comparison
| Range | Material / Finish | Size range stocked | Drive | Best suited to |
|---|---|---|---|---|
| Hobson Class 10.9 alloy steel, zinc plated | Alloy steel, zinc plated | M6 – M12 | Hex socket | General workshop and machine assembly where a plated finish is enough |
| Hobson / Bremick Grade 12.9 alloy steel | Alloy steel, zinc plated or plain | M3 – M16 | Hex socket | Higher-strength jobs — 12.9 is a full grade up on 10.9 for the same size |
| Inox World 304 (A2) stainless | 304 stainless steel | M3 – M8 (metric), 8-32 – 1/2" (UNC) | Hex socket | General corrosion resistance, food-safe and indoor/outdoor use |
| Inox World 316 (A4) stainless | 316 stainless steel | M3 – M8 | Hex socket | Marine, coastal and chemical-exposure environments |
| Inox World Black stainless | Stainless steel, black finish | M6 – M8 | Hex socket | Cosmetic black-on-black assemblies and matching black hardware runs |
| Hobson High Grade alloy steel (imperial) | Alloy steel, plain or zinc | 10-24 – 1/2" UNC, 1/4"–5/16" UNF | Hex socket | Imperial-thread machinery, US-spec equipment and legacy fixtures |
| Champion assortment refills | Mixed — hex socket and Torx drive kits | Mixed small sizes | Hex socket or Torx (check kit) | Topping up a workshop assortment case — confirm drive type before ordering |
Note on the Champion kits: the range includes both a hex-drive Button Socket Head Cap Screw Assortment Refill and a separate Torx Button Head Screw Assortment Refill. They are not interchangeable — check which drive your existing case or tool takes before reordering a refill pack.
Button Head vs Socket Head Cap Screw
The two are easy to mix up because both use a hex socket drive, but the head shape changes what each is good for. A standard socket head cap screw (the taller, cylindrical head covered by our socket head cap screws range) is built to seat into a counterbore and take a high clamp load — it's the default choice for structural and load-bearing joints. A button head socket screw has a shallower, domed head that sits above the surface. It carries a wider bearing area than a countersunk screw but a smaller one than an equivalent cap screw, so clamp load is lower for the same thread size. Reach for a button head when appearance, a low snag-free profile, or clearance above the joint matters more than maximum preload — machine guards, enclosure lids, jigs, brackets and cosmetic assemblies are the classic uses. Reach for a cap screw when the joint is structural and needs to be pulled up tight.
Allen Key (Hex) Sizes by Screw Size
Button head screws use a smaller hex key than a cap screw of the same thread diameter, because the head itself is shallower. Undersizing or rounding out the drive is one of the most common ways these get damaged on site — match the key exactly and don't force a worn or slightly-wrong key into the socket.
| Thread size | Hex key (Allen key) |
|---|---|
| M3 | 2 mm |
| M4 | 2.5 mm |
| M5 | 3 mm |
| M6 | 4 mm |
| M8 | 5 mm |
| M10 | 6 mm |
| M12 | 8 mm |
| M16 | 10 mm |
Choosing the Right Grade and Finish
Grade 10.9 vs Grade 12.9 alloy steel
Both are high-tensile alloy steel grades, and both are stocked across our Hobson and Bremick lines. Grade 12.9 has a higher minimum tensile strength than Grade 10.9, meaning a 12.9 screw can carry more load than a 10.9 screw of the same size — useful where you want to hold a size down for clearance reasons but still need the strength. If your drawing or design spec calls for a specific grade, match it exactly; don't upgrade or downgrade a fastener grade without checking the joint calculation, because a higher-grade bolt in a soft or thin material can pull through or strip the thread before the fastener itself lets go.
304 vs 316 stainless steel
304 (A2) stainless is the standard grade for general corrosion resistance — fine for most indoor and everyday outdoor use, food-contact equipment, and general fabrication. 316 (A4) stainless adds molybdenum, which significantly improves resistance to chloride attack (the pitting corrosion caused by salt air and washdown chemicals). If the application is anywhere near the coast, on a boat, in a coastal processing plant, or regularly hosed down with chlorinated or caustic cleaning chemicals, 316 is worth the small price premium over 304. Note that stainless fasteners generally have a lower tensile rating than high-tensile alloy steel grades like 10.9 or 12.9 — don't substitute stainless into a joint that was designed around a high-tensile alloy screw without checking the load.
Metric vs imperial (UNC/UNF)
Metric button head socket screws are stocked M3 through to M16, covering the vast majority of general engineering and machinery work in Australia. Imperial stock covers UNC (coarse thread) from 8-32 up to 1/2", and UNF (fine thread) in 1/4" and 5/16" only — the UNF range is narrower than UNC, so check availability before specifying a UNF button head on a design. Imperial threads still turn up regularly on older machinery, US-manufactured equipment, and some agricultural and automotive gear — get the thread form right before you order, because a UNC and metric screw of a similar nominal diameter will not interchange.
Where Button Head Socket Screws Get Used
- Machine guarding and enclosure panels — the low dome clears moving parts and operator hands better than a taller cap screw head, while still giving a positive, tool-driven fixing.
- Jigs, fixtures and tooling — hex socket drive gives good torque control and a compact head footprint in tight fixture layouts.
- Electronics and instrument enclosures — smaller metric sizes (M3–M5) with a neat, low-profile head suit panel and lid fixings where a large cap screw head would look and feel oversized.
- Cosmetic and visible assemblies — black stainless and standard finishes give a consistent, tidy look on visible hardware runs.
- Marine and washdown equipment — 316 stainless button heads resist the corrosion that would quickly attack a plated alloy steel screw in the same spot.
Companion Ranges
Button head socket screws are one part of a broader hex-socket fastener family. See our socket head cap screws for the taller-head, higher clamp-load option, socket countersunk screws for a fully flush finish, and grub screws for headless hex socket set screws. For the wider picture, browse the full fasteners range, including hex head screws and hex set screws for external-drive alternatives.
Order from AIMS
Need a size, grade or finish you can't see listed, a bulk quantity, or just want to double-check you're speccing the right screw for the job? Give our team a call on (02) 9773 0122 — we know this range inside out and can talk through the application with you. You can also reach us via our contact us page, or if you've got a full parts list to price up, send it through on our request a quote page and we'll get pricing and availability back to you quickly. As a proudly Australian-owned business, we hold stock locally and back it up with people who actually know fasteners.
People Also Ask
What's the difference between a button head and a socket head cap screw?
A socket head cap screw has a tall cylindrical head designed to seat into a counterbore and take a high clamp load. A button head socket screw has a shallower, domed head that sits above the surface, giving a lower profile and neater finish but a somewhat lower clamp load for the same thread size. Use cap screws for structural, high-preload joints; use button heads where profile, clearance or appearance matter more.
What size Allen key does a button head screw take?
It depends on the thread size, and it's a smaller key than the equivalent cap screw. M3 takes a 2 mm hex key, M4 takes 2.5 mm, M5 takes 3 mm, M6 takes 4 mm, M8 takes 5 mm, M10 takes 6 mm, M12 takes 8 mm and M16 takes 10 mm. Always match the key exactly — an undersized or worn key will round out the socket.
Can I use a button head screw instead of a socket head cap screw?
Sometimes, but check the joint first. Button head screws carry less clamp load than a cap screw of the same size because the head has a smaller bearing area, so they're not a direct swap in a high-preload structural joint. For guarding, panels, fixtures and cosmetic work where the load is light to moderate, a button head is usually the better choice because of its lower profile.
Should I choose 304 or 316 stainless for a button head screw?
304 (A2) stainless suits general indoor and everyday outdoor use. 316 (A4) stainless has better resistance to chloride attack, so it's the better choice near the coast, on boats, or anywhere the fastener gets regular washdown with salty or chemical water. If in doubt in a marine or food-processing setting, go 316.
What's the difference between Grade 10.9 and Grade 12.9?
Both are high-tensile alloy steel grades. Grade 12.9 has a higher minimum tensile strength than Grade 10.9, so a 12.9 screw can carry a greater load than a 10.9 screw of the same size. Match whatever grade your design or drawing specifies — don't substitute a different grade without checking the joint.
Do you stock button head screws in imperial sizes?
Yes. We stock imperial UNC button head socket screws from 8-32 up to 1/2" in both 304 stainless and high grade alloy steel, and UNF in 1/4" and 5/16". If you need a UNF size outside that range, get in touch and we'll check availability with our suppliers.
What length is a button head screw measured to?
Length is measured from directly under the head to the tip of the screw — the same convention used for socket head cap screws and most other screw types. The head itself is not included in the stated length.