How to cut steel with a self-tapping screw

Cutting holes in metal is a simple matter, but there are times when the usual tool is not able to provide the desired result. Or, for example, when it is cutting in hard-to-reach or inconvenient places. Let's imagine that we need to cut a round hole with a diameter of 100 mm in a thick-walled 200 mm channel. This is almost impossible to do smoothly with a drill and grinder. However, one simple device will help you do this using a self-tapping screw. In this article we will tell you how to make a simple device for cutting holes with a self-tapping screw as a cutter.

Will come in handy

Drill;
metal corner 50x50 – 0.5 m;
bolt;
nut – 2 pcs;
fluoroplastic washer;
nylon washer;
bearing (small);
hexagon 12;
self-tapping screws

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Devices for cutting metal using a self-tapping screw

In the channel we mark the center of the future hole and drill to the thickness of the bolt.

We drill 2 holes in the metal corner. We make the first hole near one end of the corner - it will be attached to the center of the circle.

A bearing with a self-tapping screw will be inserted into the second hole, so we immediately measure the required length (in our case, this is a radius of 50 mm for a round hole with a diameter of 100 mm).

Using a 12mm hexagon we will make a small but important detail. Drill a hole inside the hexagon into which the self-tapping screw will be screwed. We round off approximately 1 cm from the edge of the hexagon, leaving another 0.5 cm as is. Cut the part from the hexagon body.

We screw the screw into the part so that the rounded part of the part is at the bottom, and the cutting teeth of the screw stick out from it.

Next, fix the channel with its ribs down on a flat surface. Insert a bolt into the hole in the channel. We put a fluoroplastic washer and a corner with the outer hole on top of the bolt. Then we clamp the nylon washer with two nuts, one of which will serve as a lock nut.

We insert a part made from a hexagon into the hole with the bearing. We drill a hole through the hexagon piece - this will be the starting point for cutting with a self-tapping screw. Next, insert the screw and tighten it. The self-tapping screw will work like a milling cutter.

A drill with a bat turns a screw. Feeding forward is done with the angle as a lever.

The cutting device is ready. Lubricate the surface of the channel with a friction reducing agent (you can use regular lard). One high-quality screw is enough to cut a semicircle with a diameter of 100 mm. It is important to use high-quality self-tapping screws, because cheap ones will only last for a distance of about 20 mm.