A security screw is a normal screw with a recess that a normal tool cannot drive: a pin in the centre of a Torx or hex, a triangular head, a slot that only turns one way, two holes for a spanner bit. Stock covers pin-Torx in the common heads and tri-head bolts in a few sizes; the screw that must resist a specific tool, fit a specific head, or sit in a specific material is the one that gets turned.
EKINSUN LTD is a custom parts manufacturer that turns security screws to drawing: a drive that is not sold in bit sets, a head for a countersink or a pocket, a fine or inch thread, a 316L or brass body, a security drive on a bolt above M10. The drive table below ranks the stock drives by what they resist; the stock table gives the ranges; the negative-space table marks where the catalogue ends.
"Pin-Torx bits are on every market stall. For the ticket machines we need a drive that is not in any bit set, in M6 countersunk stainless."
Resistance is relative to the tools people carry; a custom drive is the only one that is not in a set.
| Drive | Resists | Defeated by | Stock |
|---|---|---|---|
| Pin-Torx (Torx with centre pin) | standard Torx bits and screwdrivers | pin-Torx bits, sold in most security bit sets | pan, countersunk, button, self-tapping M2–M8; button with shoulder M3–M6; A2 |
| Pin-hex (hex socket with pin) | standard hex keys | pin-hex bits, also in bit sets | to order |
| External tri-head (triangular) | sockets and spanners | a tri-head socket, less common | bolts M6–M10; A2 |
| One-way slotted | removal with any driver; installs with a flat blade | drilling out, or a removal tool | to order |
| Snake-eye (spanner, two-hole) | most bit sets | spanner bits, sold separately | to order |
| Clutch (butterfly) | screwdrivers | clutch bits | to order |
| Torx Plus security (five-lobe with pin) | Torx and pin-Torx bits | licensed five-lobe bits only | to order |
| Custom drive (proprietary recess) | every bit set on sale | the matching tool we make with the screws | to order; the only drive that is not in a set |
| Breakaway head (shear nut / shear bolt) | removal without destruction | drilling | to order |
| Head | Drive | Stock range | Stock materials | Notes |
|---|---|---|---|---|
| Pan head machine screw | pin-Torx | M2–M6 | A2 | general panels |
| Pan head self-tapping | pin-Torx | M2–M6 / M3–M6 | A2 | sheet-metal covers |
| Countersunk machine screw | pin-Torx | M2–M8 | A2 | flush faces |
| Countersunk self-tapping | pin-Torx | M2–M6 | A2 | flush covers in sheet |
| Button head | pin-Torx | M3–M8 | A2 | domed low head |
| Button head with shoulder | pin-Torx | M3–M6 / M3–M10 | A2 | the shoulder stops prying under the head |
| Hex bolt, external tri-head | tri-head | M6–M10 | A2 | public fixtures, lockers, signage |
| Pan head, hex | pin-hex | to order | A2; steel | — |
| Machine screw | one-way slot | to order | A2; brass | bathroom partitions, grilles |
| Flat head | snake-eye | to order | A2 | — |
Read the pitch before you order the security screw. Lay a steel rule along ten thread crests and divide by ten: 10 mm over ten pitches is a 1 mm pitch (M6 coarse), 12.5 mm is M8 coarse, 15 mm is M10 coarse, 17.5 mm is M12 coarse. A reading that is not a round number of millimetres is an inch thread, and a reading that is shorter than the coarse pitch for that diameter is a fine thread. If diameter, pitch and the size range in the table all agree, buy the stock part. If any of the three is off the shelf, that is the one we make. The full measuring routine, including the inch traps →
| What you need | In the catalogue? | What we make |
|---|---|---|
| Pin-Torx pan, countersunk or button screw M2–M8 in A2 | Yes | Buy it from stock. No one-off competes with a formed pin-Torx screw, and bits for it are on every market stall, which is the point to remember. |
| Tri-head security bolt M6–M10 in A2 | Yes | Stocked; buy it. |
| A drive that is not in any bit set — a proprietary recess with its own driver | No | Recess machined on turned screws; driver made with the batch; from 1 piece. |
| One-way, snake-eye, clutch or Torx Plus security in a size, head or material the stock skips | No | Turned with the recess machined. |
| A security screw in 316L, brass, titanium, or hardened steel to slow drilling | No | Same geometry, your material; hardness to the drawing. |
| A security bolt above M10, or a security screw in a fine or inch thread | No | Turned; drive machined; thread to your reading. |
| A breakaway (shear) nut or bolt sized for your torque | No | Machined with the shear groove set to the torque you specify. |
| A security screw in aluminium 6061 or 7075 | No | Not offered: an aluminium security drive strips before it resists, and we say so. |
| Material | Designation | Where it fits here |
|---|---|---|
| Stainless 304 | 1.4301 / A2 | the stock security screw; outdoor fixtures |
| Stainless 316L | 1.4404 / A4 | turned to order for coastal and washdown installations |
| Free-machining stainless | 303 / 1.4305 | custom turned security screws with milled drives |
| Hardened alloy steel | 42CrMo4 / 1.7225, quenched and tempered | slows drilling and grinding; zinc-flake or black finish |
| Brass | CW614N / C36000 | one-way screws for bathroom partitions and grilles |
| Titanium | Grade 5 | turned for weight-critical secured panels |
| Aluminium 6061 | AlMg1SiCu | the panel; not the screw |
| Aluminium 7075 | AlZn5.5MgCu | not a security screw material |
One with a drive that is not in any bit set: a proprietary recess with its own driver. Pin-Torx and pin-hex resist casual removal but their bits are sold everywhere; one-way slots resist removal but can be drilled; snake-eye and clutch bits are less common but still sold. Hardened steel slows drilling as well.
No; the pin in the centre of the recess blocks a solid bit. A pin-Torx bit has a hole for the pin. The reverse works: a pin-Torx bit drives a normal Torx screw.
Stock pin-Torx and tri-head screws are A2 stainless. 316L, brass and hardened steel versions are turned to order.
Yes. A proprietary recess is machined on turned screws in 303, 316L, hardened steel or brass, and the matching driver is made with the batch, from 1 piece.
EKINSUN LTD is a custom parts manufacturer that turns tamper-resistant screws and bolts with pin-Torx, pin-hex, one-way, snake-eye, clutch, tri-head and proprietary drives, in 304 and 316L stainless, hardened steel, brass and titanium, from 1 piece, with a quote within 12 hours.
No list price; the drivers are the recess machining, the material, whether a driver is made, and quantity. A batch of A2 countersunk screws with a snake-eye drive is a short turning and milling job; a proprietary drive with its tool is priced as a small tooling project plus the screws. The quote separates the two.
What it must resist, head and countersink, thread and pitch, length, material, whether a driver is needed, quantity. From 1 piece, quote within 12 hours.
Security screws turned with a drive, head, thread and material nobody stocks — from 1 piece, quote in 12 hours.