Specification: Material: High Speed Steel(HSS) Hardness: Up to HRC48~50 Square hole size: 1/4"(6.4mm), 5/16"(8mm), 3/8"(9.5mm), 1/2"(12.7mm) Corresponding shank size: 6.8mm, 5.5mm, 6.5mm, 8mm Suitable for bench drilling machine, mortising machine or a mortising attachment, But not for any hand drill Package included: 4pcs woodworking chisel drill bits
How to install these square drill bits?
1.The drill core is very sharp. Wear working gloves to avoid direct contact between your hands and the drill bit during installation.
2. Put the square drill shell and drill core into the jig of the square tenoning machine, and then hold the square hole drill bit by hand
3. Take 0.5~1mm thick sheet (metal sheet or plastic sheet) and jam it at the step of the drill shell. After fixing the drill core, remove the sheet, then adjust the angle of the drill shell to the top to ensure clamping, so that a 0.5~1mm gap can be formed between the drill core head and the inner bevel of the drill shell, which can prevent the bit from jamming during use .