How to make a hex hole in metal

It is possible that the need for hexagonal holes may arise when making homemade devices or repairing faulty equipment. For this purpose, there is, for example, a series of expensive tools.
In order not to waste money, you can try to make a device with the given functions yourself, for which you need to have at least basic plumbing skills, as well as stock up on some tools and materials.

Will need

The following tools and devices will help us in the upcoming work:

• drilling machine or electric drill;
  
• drills of the required diameter;
  
• electromechanical emery wheel;
  
• bench vice;
  
• hacksaw or grinder;
  
• a set of spacers (pieces of thick-walled pipes of various lengths);
  
• extension for the vice gate (a piece of suitable pipe).

To make the required tool, a kind of broach, we use the working part of a hex key (Allen key, Allen key) with a working section of a suitable cross-section.It is designed for tightening and unscrewing screws that have a cylindrical head and a hexagonal socket.

Process for creating a hex hole tool

This stage is the most responsible and important, since the quality of the proposed hexagonal hole in the metal will depend on the reliability and accuracy of the dimensions of the planned broach.
The work sequence should be approximately as follows:
1. Usually hex keys are L-shaped. Cut off the short part (handle) below the fold with a hacksaw or grinder.
2. We form a workpiece from the flat (working) part with a length of 50 to 75 mm, depending on the transverse size of the future tool.

3. Using suitable means (emery wheel, very hard file), we give the workpiece the shape of a light, uniform cone, maintaining the same cut in any section along the perimeter.
4. Using the edges of the emery wheel, we form three to five transverse rings.

They are needed to improve the cutting properties of the device and accumulate (retain) the metal removed during processing.

Hex hole forming process

We carry out this work in the following sequence:
1. First, you need to drill an auxiliary hole in the metal with a drill or on a drilling machine with a diameter that can be calculated using a very simple relationship obtained experimentally:

For example, if it is 15 mm thick (the distance between opposite edges), the diameter of the preliminary hole should be: 15 mm × 1.020 = 15.30 mm.



2.We insert the guide part of the homemade tool into the drilled hole in the metal part and, for reliability, lightly hit the opposite end with a hammer.

3. We place the resulting structure (a metal plate with a tool fixed in it, forming a hexagonal hole) between the jaws of the vice and install a spacer of suitable length on the side of the broach exit for receiving a homemade tool.

4. Move the jaws of the vice by rotating the gate. In case of high resistance, we put an extension on the collar to increase the shoulder and, accordingly, the clamping force. We continue this process until the broach completely passes through the metal plate.

5. Unclench the jaws of the vice and use a hammer to knock the broach out of the formed hole in the opposite direction. To improve the quality of the hole, we run the broach on the other side in the same order as in point 4.

6. The final operation involves removing residual metal particles and formed burrs. To do this, you can use a grinder, a file and sandpaper.

The metal in which we are going to make a hex hole should not be harder than the material of the working part of the Allen key.
Original article in English