If you are going to work with bolts that have a semicircular head and a square head, then the hole on the side of such fasteners should be square to prevent it from turning. Bolts of this configuration are most often used in construction and manufacturing furniture for connecting wooden and metal parts or parts.
It is very simple to make a square hole on a special machine or even on a lathe, but this requires a special device. But there are ways when it can be done manually, using the simplest and most accessible tools.
Will need
To complete the work ahead, we need to prepare:
- a metal plate with a round hole;
- chisel for working on metal;
- hammer;
- bench vice.
Procedure for making a square hole in a metal plate
The diameter of the round hole in the plate and the side of the square bolt head should be related as a circle inscribed in a square.Otherwise, the square hole will either be too small and will have to be further expanded, or too large, and then the bolt head will rotate freely in it. In this case, there will be no way to tighten the bolt, because its semicircular head does not have a slot or slot.
For the method under consideration for making a square hole in a metal sheet, marking is very important. First, along the edges of the hole, we apply four strokes along the continuation of mutually perpendicular diameters.
Then we set an angle of 45 degrees from each stroke and also draw strokes. Their lengths should be equal to the distance between the inscribed circle and the angle of the square, which can be determined by drawing a drawing on paper on a scale of 1:1 and measuring the size we need with a ruler.
Using a chisel, we make cuts along the marks, strictly observing their length. All of them, naturally, should be the same in size.
We clamp the plate with the hole in the vice so that the ends of the adjacent slots with their outer ends are at the level of the upper edge of the jaws of the vice, which must, of course, be strictly horizontal.
Using a sharp chisel and hammer, select the metal between the two slots exactly along the upper edge of the vise jaws.
We repeat the same operation three times, rotating the plate 90 degrees each time.
As a result, we will get a neat square hole that exactly matches the head of our bolt.
