In the practice of the house master, there are cases when you need to drill a large diameter hole, and nothing. In this case, will help improvised hollow drill bit, suitable for non-ferrous metals, plastics, wood. It leaves a cylindrical disc, which can also be used, and quite a bit of shavings.
The basis of drill — steel pipe of suitable diameter, the end of which is soldered six cutters made of hard alloy. In the opposite end welded mandrel with Morse taper No. 3 or No. 4.
In the wall of the pipe to make a hole for the exit of chips from the cavity during drilling.
1 — bar, 2 — tubular housing, 3 — insert.
V. BEZRUKOV, Vyazemsky, Khabarovsk Krai