Spline Socket Keys (Inch Sizes) — Companion Drive Tool
Spline socket keys, nominal socket sizes 0.033 – 0.790 in — the xzn-shaped drive hardware that turns spline-socket set and cap screws, with the collected per-size table: tooth counts, socket major/minor diameters and the key's P dimension.
Last updated: 2026-11
Specifications
The spline socket system replaces the hex socket's six flats with a multi-tooth star profile — the table shows 4, 6, or both tooth counts at a given nominal socket size — and its driver is the spline socket key: a short blade of matching profile on a handle, the same role the hex key plays for hex sockets. The table runs nominal socket sizes 0.033 through 0.790 in (a far finer small end than the hex key ladder, reaching sizes for miniature screws) and carries per size: number of teeth, socket major diameter M (max/min — the profile's outer envelope, e.g. 0.098/0.097 at 0.096), socket minor diameter N (max/min — the tooth-root circle, 0.082/0.080 at 0.096) and the P dimension (max/min, 0.022/0.021 at 0.096 — the tooth-width parameter that distinguishes the profile proportions). Read it as a mating pair: the screw's socket is specified by its nominal size, and the key must match both the size and the tooth count — the table deliberately lists 0.048 and 0.069/0.076 in two tooth counts (4 and 6) with different N and P values, so a 4-tooth key does not drive a 6-tooth socket even at the same nominal size. That also makes the spline system a tamper-resistant choice: the drive hardware is not the household hex key. The size ladder is irregular (see the table footnote), and the 0.096 size appears twice with identical values — both reproduced verbatim. Key material, hardness and finish are not tabulated — per RFQ.
| Product type | Companion drive hardware for spline-socket screws (not a fastener) — supplied as installation tooling |
|---|---|
| System | Spline (xzn) socket drive — multi-tooth profile, 4 or 6 tooth counts by size; key and socket must match in both nominal size and tooth count |
| Size range | Nominal socket size 0.033 – 0.790 in, twenty-one distinct sizes; irregular ladder reproduced verbatim |
| Tabulated geometry | Per size: teeth, socket major dia. M (max/min), socket minor dia. N (max/min), P dimension (max/min) — e.g. 0.096: M 0.098–0.097, N 0.082–0.080, P 0.022–0.021 |
| Dual tooth counts | 0.048 (4 and 6), 0.069 and 0.076 (4/6) carry distinct N and P per tooth count — profile proportions differ, keys are not interchangeable across tooth counts at the same size |
| Material / hardness / finish | Not tabulated by the collected specification — per RFQ (state the screw sizes the keys must drive and the service environment) |
| Nominal Socket Size | Number of Teeth | Socket Major Dia. (M) Max | M Min | Socket Minor Dia. (N) Max | N Min | P Max | P Min |
|---|---|---|---|---|---|---|---|
| 0.033 | 4 | 0.035 | 0.034 | 0.0275 | 0.0260 | 0.0120 | 0.0115 |
| 0.048 | 4 | 0.050 | 0.049 | 0.0395 | 0.038 | 0.017 | 0.016 |
| 0.048 | 6 | 0.050 | 0.049 | 0.041 | 0.040 | 0.011 | 0.010 |
| 0.060 | 6 | 0.062 | 0.061 | 0.051 | 0.050 | 0.014 | 0.013 |
| 0.069 | 4/6 | 0.071 | 0.070 | 0.0545 | 0.053 | 0.021 | 0.020 |
| 0.072 | 6 | 0.074 | 0.073 | 0.064 | 0.063 | 0.016 | 0.015 |
| 0.076 | 4/6 | 0.079 | 0.078 | 0.0575 | 0.056 | 0.023 | 0.022 |
| 0.096 | 6 | 0.098 | 0.097 | 0.082 | 0.080 | 0.022 | 0.021 |
| 0.096 | 6 | 0.098 | 0.097 | 0.082 | 0.080 | 0.022 | 0.021 |
| 0.111 | 6 | 0.115 | 0.113 | 0.098 | 0.096 | 0.025 | 0.023 |
| 0.145 | 6 | 0.149 | 0.147 | 0.128 | 0.126 | 0.032 | 0.030 |
| 0.168 | 6 | 0.173 | 0.171 | 0.150 | 0.147 | 0.036 | 0.033 |
| 0.183 | 6 | 0.188 | 0.186 | 0.163 | 0.161 | 0.039 | 0.037 |
| 0.216 | 6 | 0.221 | 0.219 | 0.190 | 0.188 | 0.050 | 0.048 |
| 0.251 | 6 | 0.256 | 0.254 | 0.221 | 0.219 | 0.060 | 0.058 |
| 0.291 | 6 | 0.298 | 0.296 | 0.254 | 0.252 | 0.068 | 0.066 |
| 0.372 | 6 | 0.380 | 0.377 | 0.319 | 0.316 | 0.092 | 0.089 |
| 0.454 | 6 | 0.463 | 0.460 | 0.386 | 0.383 | 0.112 | 0.109 |
| 0.595 | 6 | 0.604 | 0.601 | 0.509 | 0.506 | 0.138 | 0.134 |
| 0.620 | 6 | 0.631 | 0.627 | 0.535 | 0.531 | 0.149 | 0.145 |
| 0.698 | 6 | 0.709 | 0.705 | 0.604 | 0.600 | 0.168 | 0.164 |
| 0.790 | 6 | 0.801 | 0.797 | 0.685 | 0.681 | 0.189 | 0.185 |
- Row 9 (0.096): Duplicate rows appear at 0.096 (two identical rows) — reproduced verbatim.
- Row 1 (0.033): The size ladder is irregular (jumps such as 0.048 → 0.060 → 0.069 and 0.595 → 0.620 → 0.698); the "P" dimension carries no label beyond "P" in the published header — reproduced as printed.
Materials
- Key material and hardness specified per RFQ — spline keys turn small, high-torque screws; state the screw series and duty with the order
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (Spline Socket Keys (Inch Sizes) — Companion Drive Tool) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
How do I match a spline socket key to a spline-socket screw?
Match two things, in this order: nominal socket size first, tooth count second — either alone will mislead you. The collected table shows why tooth count matters: at 0.048 the 4-tooth profile has a minor diameter of 0.0395/0.038 and P of 0.017/0.016, while the 6-tooth profile at the same nominal size runs 0.041/0.040 and 0.011/0.010 — different tooth proportions, so the keys are not interchangeable and forcing one into the other rounds the tooth roots. Read the screw's socket nominal size (0.033 through 0.790 in on this table), confirm the tooth count from the screw's own drawing or by counting lobes under a loupe at the small end, and pick the key row with both. The M and N columns then serve as wear gauges: a key or socket worn past its max/min envelope starts to cam out, the same failure mode that pushed hex systems toward deeper engagement — spline's answer is the finer tooth division, which spreads the torque over more contact points and resists cam-out better than a hex of the same outer diameter. Two data notes from the source itself: the size ladder is irregular (0.048 → 0.060 → 0.069 → 0.072 → 0.076, among other jumps — reproduced verbatim, sizes are not invented between steps), and key material and hardness are not tabulated — quote those with the screw sizes the keys must drive.
What is the MOQ and lead time for this item?
The minimum order quantity is 10,000 pieces. Stock items ship in 3–7 days; non-stock items are confirmed at quotation. Confirm the exact schedule against quantity and size mix at quotation.
Related knowledge
- Thread-Forming vs Thread-Cutting vs Thread-Rolling Self-Tapping Screws: What the Evidence Settles on Base Material
- Screw Family Selection by Base Material: Wood, Machine and Self-Tapping Threads, Engagement and Coating
- Hex Bolts vs Socket Head Cap Screws: What the Evidence Settles on Strength, Clearance and Cost
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support