Drilling – Bits
| Spade Type | Thread Shank Size | Drill Bit Diameter (mm) | Tungsten Carbide Grade | Flushing Hole Diameter (mm) |
|---|---|---|---|---|
| Centre Flush | 16mm | 27 | Standard | 8 |
| Centre Flush | 16mm | 28 | Heat Resistant | 8 |
| Extra Flush | 1/2" Whiteworth | 27 | Standard | 5 |
| Extra Flush | 1/2" Whiteworth | 28 | Heat Resistant | 5 |
Key Features
- Eccentric tip and negative rake.
- Fast penetrating two wing drill bit for wet drilling suitable for most types of rock.
- The negative front rake, and eccentric tips, makes it suitable for hard rock.
- The standard grade of tungsten carbide insert provides extremely good wear resistance and is time proven for all types of conditions. Unless otherwise specified the standard grade of carbide is assumed.
- For abrasive conditions, such as found with some sand stones, the tungsten carbide inserts can be supplied in a heat resistant grade. However these inserts may chip under high impact loading.
- Centre Flush drill bits have an 8mm diameter centre hole and Extra Flush Bits have a central water hole plus two side water grooves for extra flushing.
- The drill bit body is specifically designed for clearance of rock cuttings. The body is made of high tensile material for strength and abrasion resistance.
- Reference should be made to DSI Underground’s "Practical Guide to Rock Bolting" highlighting installation problems associated with collaring the hole, angle bolting, hole diameter and depth.
