Such fixtures, also known as drill bits, is designed to create square holes and grooves - the most famous and most common joints known throughout the history of carpentry. The fixtures are made of high-speed HSS steel and consist of two parts - a square bit and a drill.
The principle of the nozzle is as follows: a drill drills everything inside, and a pointed shirt-chisel hollows out the remaining tree in the shape of a square of a certain size. Wood chips come out of a groove located on one side of the bit.
The product package is as follows:
• 1 PC. for grooves of 10 mm x 10 mm (slot depth: 61 mm; drill length: 195 mm; shank diameter: 19 mm);
• 1 PC. for grooves of 16 mm x 16 mm (slot depth: 77 mm; drill length: 218 mm; shank diameter: 19 mm).
As the name implies, the device is suitable only for mortising machines, or it can be installed on drilling machines using a special device - a mortising device (DS-60 from Promo, others were not on sale, the price of a set with drills is about 4-5 thousand rubles, the device itself separately - about 800 rubles)
In conclusion, it remains to add that the purchase of such a set is advisable from the point of view of saving money both in case you have a grooving machine and as an addition to the purchased grooving device (unfortunately, we could not find it on Ali).
Cost: ~ 994