How to cut a straight hole with a grinder
At home, only a grinder will help you quickly and accurately make a large-diameter hole in steel. Of course, you can drill it around the perimeter with a thin drill, and then grind the perforated edge for a long time, but this takes time. A gas cutter or welding will not help in this case, since they melt the edge. To cut straight holes with a grinder, you need to use a couple of tricks, which we will consider.
The outline of the future hole is marked on the metal.
An old worn-out cutting wheel is installed on the grinder.
It has a small diameter, so when cutting it touches the metal with a smaller area. With its help you need to cut a small recess along the contour of the hole. It is enough to go literally 1/3 of the thickness of the steel. Since the worn cutting disc has a small diameter, the cut will be smooth, without the formation of notches outside the circle.
Having scratched the outline of the hole, a new cutting disc is installed on the grinder.They already cut out a square through window in the center of the circle. It should not reach the boundaries of the drawn circle by a few centimeters, maybe more.
Now you need to remove the remaining part of the metal between the outline of the round hole and the border of the square cut out in it. To do this, use a grinder to split the excess steel into sectors 1-1.5 cm wide. If the metal is thick, then when making cuts it is better to keep a small step.
Next, along the edge of each sector, blows are applied with a hammer through a chisel or punch.
The metal is bent and then returned to its original position with blows from the reverse side. It needs to be broken like a wire. It's not difficult at all. If the diameter of the hole allows, then the metal can be bent with pliers. It is necessary to break out all segments sequentially.
If the worn cutting wheel had a small diameter, and when broken, the metal dissolved into narrow segments, then the resulting hole will have the shape of an almost perfect circle. It doesn't even need to be sanded. A similar method can be used if necessary to make a hole in a tile. Only in this case will the segments be broken with pliers immediately, without bending back and forth.
Tools:
- grinder 125 mm;
- new cutting disc 125 mm;
- old almost worn out cutting disc;
- hammer;
- chisel or breakdown;
- pliers.
Hole cutting
The outline of the future hole is marked on the metal.
An old worn-out cutting wheel is installed on the grinder.
It has a small diameter, so when cutting it touches the metal with a smaller area. With its help you need to cut a small recess along the contour of the hole. It is enough to go literally 1/3 of the thickness of the steel. Since the worn cutting disc has a small diameter, the cut will be smooth, without the formation of notches outside the circle.
Having scratched the outline of the hole, a new cutting disc is installed on the grinder.They already cut out a square through window in the center of the circle. It should not reach the boundaries of the drawn circle by a few centimeters, maybe more.
Now you need to remove the remaining part of the metal between the outline of the round hole and the border of the square cut out in it. To do this, use a grinder to split the excess steel into sectors 1-1.5 cm wide. If the metal is thick, then when making cuts it is better to keep a small step.
Next, along the edge of each sector, blows are applied with a hammer through a chisel or punch.
The metal is bent and then returned to its original position with blows from the reverse side. It needs to be broken like a wire. It's not difficult at all. If the diameter of the hole allows, then the metal can be bent with pliers. It is necessary to break out all segments sequentially.
If the worn cutting wheel had a small diameter, and when broken, the metal dissolved into narrow segments, then the resulting hole will have the shape of an almost perfect circle. It doesn't even need to be sanded. A similar method can be used if necessary to make a hole in a tile. Only in this case will the segments be broken with pliers immediately, without bending back and forth.
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