🔘 M3 x 40mm Aluminium Knurled Thumb Screw – Anodised Hand Grip Knob Bolt for Machinery & Precision Moulds
You’re setting up a jig, adjusting a mould, or working on a bearing assembly – and you need a thumbscrew that reaches deep into the equipment without tools. This M3 x 40mm aluminium knurled thumb screw gives you a long, fully threaded stud (40mm under head) combined with a comfortable, diamond‑knurled head. Made from 6061 aluminium with a durable anodised finish, it’s lightweight, corrosion‑resistant, and won’t strip or slip. Perfect for machinery adjustments, precision moulds, jigs, and any application where a long‑reach, tool‑less hand grip is required.
✨ Key Features – M3 x 40mm Aluminium Thumb Screw
- 🔘 Knurled round head – Fine diamond knurling for a secure, non‑slip fingertip grip – no tools needed.
- 📏 40mm fully threaded stud (under head) – Long reach for thick panels or deep recesses. Fully threaded for maximum grip.
- ⚖️ Lightweight 6061 aluminium – About 1/3 the weight of steel. Non‑magnetic and thermally conductive.
- 🎨 Anodised finish – Corrosion‑resistant, durable, and available in various colours (contact us for options).
- 🛡️ M3 metric thread (3mm diameter, 0.5mm pitch) – Standard size for electronics, small machinery, and precision instruments.
- ✨ High quality workmanship – Smooth, burr‑free surface, even threads, uniform force – no slipping or stripping teeth.
- 🔧 Widely used – Machinery, precision moulds, bearing assembly, jigs, fixtures, and industrial equipment.
📏 Specifications – M3 x 40mm Knurled Thumb Screw (Aluminium)
| Thread Diameter (M) |
Thread Pitch (mm) |
Thread Length (mm, under head) * |
Head Style |
Head Diameter (approx.) |
Head Height (approx.) |
Material / Finish |
Tolerance |
| M3 |
0.5 |
40 mm |
Round knurled |
~8‑10 mm |
~5‑7 mm |
6061 aluminium / Anodised |
±0.2 mm |
* Length measured from underside of head to tip. Fully threaded. Colour may vary slightly due to photography and lighting – actual anodised colour may differ.
🛠️ Where to Use This Long‑Reach Thumb Screw
| Application |
Typical Use |
| Machinery & equipment |
Adjustment screws on deep frames, access panels, tool‑less clamps |
| Precision moulds |
Quick‑release fasteners, alignment pins, deep‑throat clamps |
| Bearing assembly & jigs |
Adjustable stops, deep‑set screws, fixture handles |
| DIY & prototyping |
Custom fixtures, 3D printer bed leveling (long reach), camera rigs |
❓ Frequently Asked Questions – M3 x 40mm Aluminium Thumb Screw
1. How do I measure the length of this thumb screw?
The length (40mm) is measured from the underside of the head (where the knurling meets the shaft) to the tip of the threaded stud. The head itself is NOT included. This 40mm stud is designed for applications that require a long reach through thick panels or into deep recesses.
2. Is the screw fully threaded? Can I use it with a nut?
Yes – it is fully threaded from under the head to the tip. If you need to fasten through a plain hole, use an M3 metric nut (0.5mm pitch). For pre‑tapped M3 holes, no nut is needed.
3. What colours are available? The photo shows a certain colour – will mine match exactly?
We offer a range of anodised colours (black, silver, red, blue, gold, green, etc.). Actual colour may vary slightly between batches or due to monitor calibration – this is normal. Please contact us for specific colour availability.
4. Will the anodised finish wear off? Is it durable?
Anodising is a hard, electrochemical finish that bonds to the aluminium. It resists scratches and fading far better than paint. Normal hand use will not remove the colour.
5. Can I use this screw outdoors? Will it rust?
Aluminium naturally forms a protective oxide layer, and anodising adds extra corrosion resistance. It is suitable for indoor and light outdoor use. For continuous saltwater or harsh chemical environments, consider stainless steel thumb screws.
6. Can I get other lengths or custom colours?
Yes – we offer custom lengths and anodised colours. Please contact us with your requirements.
