Milsons offer a comprehensive size range of Coach Screws available in Mild Steel with an HDG finish and 304 & 316 Stainless Steel. These heavy-duty fasteners are commonly used for joining timber and masonry surfaces. Coach Screws typically feature an external hex or countersunk internal hex head, an unthreaded shank, and a threaded portion that tapers to the point.
Installation in Timber
When using Coach Screws to fasten into timber, it’s essential to pre-drill pilot holes to prevent the wood from splitting. Refer to the table below as a guideline for drilling pilot holes. In the case of over-tightening the screw will embed its head into the timber. To avoid this, it is advisable to use a washer beneath the screw head. Additionally, applying grease to the Coach Screw can reduce installation friction, particularly when installing larger diameters in hardwood.
Screw Diameters Pilot Holes
| Screw Size | Hard Wood | Soft Wood | Countersunk Size |
|---|---|---|---|
| 4G | 5/64 | 1/16 | 1/4 |
| 6G | 7/64 | 3/32 | 5/16 |
| 8G | 1/8 | 7/64 | 3/8 |
| 10G | 9/64 | 1/8 | 7/16 |
| 12G | 5/32 | 9/64 | 7/16 |
| 14G | 11/64 | 5/32 | 1/2 |
| 16G | 3/16 | 11/64 | 9/16 |
| 18G | 7/32 | 13/64 | 5/8 |
Screw Diameters
| Screw Diameter | mm | Nearest Frictional Measurement |
|---|---|---|
| 4G | 2.84 | 7/64 |
| 6G | 3.51 | 9/64 |
| 8G | 4.17 | 5/32 |
| 10G | 4.83 | 3/16 |
| 12G | 5.49 | 7/32 |
| 14G | 6.15 | 1/4 |
| 16G | 6.81 | 17/64 |
| 18G | 7.47 | 19/64 |
Installation in Masonry or Concrete
For applications involving masonry or concrete, Coach Screws are commonly installed with appropriately sized wall plugs. To determine correct hole diameters, load capacities and the most suitable wall plug for your application, contact our knowledgeable sales team today.
The data provided in this document is for general guidance only and should not be solely relied upon when working to stringent specifications. We recommend consulting with qualified experts regarding any technical queries. This may change without written notice
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