To drill a large hole, you need a crown, whether purchased or homemade. Naturally, homemade is preferable, since it costs practically nothing. If the store is far away, then doing it yourself is the most convenient solution.
Materials:
- steel pipe;
- washer or sheet steel;
- M8-M12 bolt with nut.
Crown manufacturing process
For a crown, you need to select a pipe that matches the diameter of the desired hole. A piece of the required length is cut from it. The longer it is, the deeper you can go through the walls when drilling, but you should not overdo it, so as not to overload the drill.
A nut of suitable diameter is welded into the end of the pipe exactly in the center. If the pipe is large, then a sheet metal disk with a hole in the center is welded into it.
From inside the pipe, a bolt no thicker than the size of the drill chuck is inserted into the hole. A nut is tightened onto it from the outside. For reliability, it can be welded to the pipe.
Then the workpiece is clamped in a vice and the teeth are cut on it with a grinder, like on a saw.
The result is a completely working crown, albeit without a centering drill. You can get used to drilling without it, simply pressing it against the wall, and only then turning on the rotation.
