How to make square holes with round drills, a method accessible to everyone

When manufacturing various mechanisms, it may be necessary to drill a square hole. There is a Watts drill for this, but not everyone has it. If purchasing it is not practical, then using simple technology you can make a square hole using ordinary metal drills.

Tools:

• center punch;
  
• hammer;
  
• drill or drilling machine;
  
• center drill;
  
• basic drill 4 mm or larger, depending on the size of the square hole required;
  
• a large drill with a diameter 1 mm smaller than the side of the future square;
  
• metal file.

Drilling a square hole

For ease of work, you need to cut out a square template from paper, but smaller than the required hole by the diameter of the main drill. For example, if you need a square of 10x10 mm, and a 4 mm drill will be used as the main one, then the template is cut with sides of 6x6 mm.

Important! When choosing the main drill, you need to ensure that its 2 diameters are slightly smaller than the side of the template.In this case, when drilling, the holes will not overlap each other and the drill will not jump off the desired point.
The paper square is glued to the workpiece with tape. Using a punch, clear deep notches are applied in its corners and center. Afterwards the template is removed.

The notches are lightly drilled out with a centering drill.

Next, you need to make through holes along the corner marks. Ideally, use a drilling machine, since working with a drill may reduce accuracy. If you need to drill through thick metal, you will definitely need oil to cool the edge of the drill.


After the corners are ready, using a large drill, a central notch is drilled between them. This allows you to choose the metal in the middle. The result is a blurry square hole.


Using a needle file, flat or triangular file, the hole is brought to the correct square. Particular attention should be paid to rounding the corners to grind them down to 90 degrees. It is advisable that the width of the file corresponds to the side of the square hole, then it will be possible to carry out the boring almost perfectly.


This drilling method is labor-intensive and takes at least half an hour, taking into account finishing with a file, but it allows you to get a fairly high-quality hole. Its main advantage is the ability to get by with a meager set of tools without the need to purchase a Watts drill.

Watch the video

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