To make a center punch with your own hands of increased accuracy, you will need a keyless chuck of an electric drill and a reamer (cutting tool). In general, any steel bar of suitable diameter can be used. But it is better to rely on a cutting tool that is made of high carbon steel.
By the way, instead of a reamer, you can also use a machine tap for threading - normal for this homemade product will not work.
If you use a cutting tool made of high carbon steel (reamer or tap), then first of all you need to "remove" the hardening. We heat the end of the rod over a gas stove or using a gas spray, and leave to cool at room temperature.
The main stages of work
After the vacation, we cut the M5 thread at the tip of the bar. The end of the rod itself must be sharpened onto the cone using a metal file. On the opposite side of the reamer, we also cut the M5 thread. Moreover, in this case, the thread should be about 15 mm long.
Next, you need a sleeve with an outer diameter of 12 mm. It is necessary to drill a hole in it and cut the internal thread M5.
At the next stage, you will need to slightly modify the sds adapter to the keyless chuck - cut off the shank and drill a through hole with a diameter of 5 mm. Then we cut off the threaded part on the adapter, leaving only 2-3 threads.
At the last stage of work, cut a piece of spring 10 mm, and then collect the punch. For convenience, you can make a wooden handle. For details on how to make a high accuracy punch yourself from a drill and reamer cartridge, see the video on the website.
