Countersink is a metal cutting tool with several working blades, designed for machining pre-drilled holes of cylindrical or conical shape. Using a countersink, when choosing the necessary type of tool, it is possible to obtain recesses of various configurations in the holes of the workpieces. Do not confuse countersink with countersinking, drilling holes to the full length to improve surface quality. If you want to choose the most suitable countersink, it is best to use countersink bits reviews. So you will have the opportunity to learn as much as possible about the various types of zinc plating and select the appropriate option.
Types and use of countersinks
When machining parts on drilling and turning machines, a countersink for metal is used for:
- The formation in pre-prepared holes of the recesses of a conical or cylindrical shape of the required length.
- The formation of reference planes near the holes.
- Chamfering holes.
- Processing holes for fasteners.
- Often you can find the term “reeling”, the so-called tool designed for drilling recesses of a cylindrical shape and supporting planes.
According to the configuration of the cutting part, the following types of countersinks are found:
- Cylindrical configuration.
- Conical countersinks.
- Face tools.
According to the diameter of the machined holes, countersinks are divided into:
- Simple (from 0.5 to 1.5 mm).
- For holes with a diameter of 0.5 to 6 mm. Available with or without safety cone.
- Countersinks with tapered shank. Are applied to openings with a diameter from 8 to 12 mm.
Conical countersink consists of two main elements – the working part and the shank. The working part has a cone with a standard range of angles on top from 60 to 120 °. The number of cutting blades depends on the diameter of the tool and can be from 6 to 12 pieces.
The cylindrical countersink is similar in design to a drill, but has more cutting elements. At the end there is a guide pin necessary for fixing the position of the tool during processing. The limiter can be removable or be part of the body of the tool. The first option is more practical, as it expands the processing capabilities. A cutting nozzle can also be installed.
If it is necessary to drill several holes to an equal depth, a tool with holders with a rotating or fixed stop is used. Before processing, the countersink is fixed in the holder so that the cutting part protrudes from the stop by a distance equal to the required depth of processing of the holes. The tool is made of tool alloyed, carbon, high-speed and carbide steel grades. Carbide steels are most often used for machining cast-iron parts; high-speed and tool steels are used for ordinary steels.
Features of countersinking holes
Here are some recommendations for metal working by countersinking:
- When processing hard alloys and cast iron, it is necessary to use cooling emulsion compositions to remove heat.
- It is very important to choose the right tool for the job. It is necessary to take into account the material of the workpiece and the nature of the work.
- When tampering the countersink, pay particular attention to the specified processing parameters – diameter, required accuracy, size of the recess.
- Pay attention to the fixing method on the machine; if necessary, purchase the necessary additional equipment.
How to choose a countersink size?
In order for the screw to sit perfectly in the flush, it is important to choose the conical countersink correctly for the hardware head and countersink the hole to the exact depth equal to the height of the head. The angle of the tool should correspond to the angle of the cone of the head, and its diameter to the diameter of the head. If you take a too large countersink, the head will be buried in the “crater” of the hole, and if it is smaller, it will protrude above the plane, which also does not look aesthetically pleasing.