Forstner drill bit with saw tooth Inch sizes
Forstner drill
Forstner drill bit
This forstner drill has saw teeth that cut the outside of the hole. This type of drill bit is designed for drilling against the grain of the wood, i.e. on the face of the wood, but it also drills well in MDF, hardwood and melamine. The shape of the chuck makes these drills easy to re-sharpen. With a diamond file, the job is done in no time. Large diameters are also available. Large diameters (80 mm and larger) can be used in column drills and lathes with considerable torque (1.1 kW motor).
Extensions for the Forstner drill bit
For drill bits up to 2’ in diameter, this is the forstner drill bit extension .
For drills with a diameter from 2 1/2’ onwards, this is the forstner drill extension piece.
Specs:
easy to resharpen
150 mm long
fitting of drills with a diameter of up to 2" is 3/8 in.
inclusion of drills with a diameter of 2 1/2" and larger is 1/2 inch.
Speed
Too high a speed can harm the forstner drill bit. Below is a table as a rule of thumb when drilling:
| Ø Inch | recommended speed for soft wood | |
| " |
RPM |
|
| 1/2 (12,7 mm) | 1.400-1.200 | |
| 3/4 (19,05 mm) |
1.400-1.200 | |
| 7/8 (22,225 mm) |
1.200-1.000 | |
| 1 (25,4 mm) |
1.200-1.000 | |
| 1 1/4 (31,75 mm) |
1.000-800 | |
| 1 1/2 (38,1 mm) |
900 - 700 | |
| 2 (50,8 mm) |
700 - 600 | |
| 2 1/2 (63,5 mm) |
500 - 400 | |
| 3 (76,2 mm) |
400 - 300 | |
For hard woods go down a little more in revs
| diameter | 1/2 inch or 3/4 inch or 1 inch or 7/8 inch (14,22 mm) or 1 1/4 inch (31,75 mm) or 1 1/2 inch (38,1 mm) or 2 inch (50,8 mm) or 2 1/2 inch (63,5 mm) or 3 inch (76,2 mm) |