To drill a hole in a metal workpiece exactly according to the set mark, it is best to use a spring punch for this - a bench tool whose task is to mark the central holes.
The drill is inserted into the groove, due to which it does not slip on the metal surface at the initial stage of drilling. To make a homemade spring punch, a workpiece of high-quality steel is required. For example, you can use a car valve for this. You will also need two washers, a spring and a nut.
The main stages of work
First of all, you need to sharpen the end of the automobile valve stem - for this we grind the workpiece under a cone on a grinding machine or using a grinder with a petal disk. After that, the pointed part must be hardened.
Then we take a nut and weld two washers on both sides of it. You will also need another nut of a smaller diameter, in which it is necessary to drill a hole so that it can be welded to the stem of the automobile valve (it does not make sense to completely weld the nut).
The principle of operation of the spring center punch is very simple: due to compression and sharp release of the spring, the hammer (nut) is driven, which strikes the lower nut welded to the shaft of the automobile valve.
At the last stage of work, we assemble the spring punch. We put a spring on the valve, then a large nut, and then weld a small nut at a distance of 2 cm from the edge. Before you make such a tool for yourself, watch the video, which clearly shows the entire process of assembling the punch.
