Feature：

7 Sizes: shank type: round handle, 6/25 inches (6 mm), 1/4 inches (6.4 mm), 5/16 inches (8 mm), 3/8 inches (9.5 mm), 2/5 inches (10 mm), 1/2 inches (12.7 mm), 9/16 inches (14 mm), totally 7 different sizes
Material: made of high-speed steel, with high hardness up to HRC48 - 50, durable and practical, being heat treatment for a long-term use
Application: mortise drill bits are suitable for mortising machine or mortising accessories, which can greatly improve the working efficiency of carpenter, also suitable for installation, decoration and other industries
Fine workmanship: finished with fine polishment, these square drill bits come with no burrs to provide you a smooth drilling experience
Notice: square hole drill needs to cooperate with square hole drill machine (mortise and tenon) use and can not use with hand-operated electric drill

Description：

Using steps:
1. Drag the core and shell into the equipment fixture and drag.
2. Take a 0.5 - 1 mm thick sheet (metal sheet or hard plastic sheet) stuck at the step of the drill shell.
3. After fixing the drill core, remove the slice, and then adjust the angle of the drill shell and press it upward and clamp it (the purpose is to form a 0.5 - 1 mm gap between the head of the drill core and the inner angle of the drill shell to avoid the bit stuck dead).

Package List:

7 x Square hole drill bits (7 sizes which are shown above)

Notes:

Please allow a little error on the size due to manual measurement.