Drill a round hole in a material of any density within the power of everyone. But what if you need a square hole? To many, the possibility of drilling a square in soft, pliable wood or in a piece of durable metal will seem implausible. The Watts drill copes with this difficult task.
Story with geometry
Masters today, to obtain a square hole, drill a round hole of the appropriate diameter and punch out the corners with special tools. Much faster and easier to perform this operation can be a "square" Watts drill. The basis of its design is the Reuleaux triangle - a figure formed by the intersection of three identical circles. The radii of these circles are equal to the side of a regular triangle, and its vertices are the centers of the circles.
The figure bears the name of the German scientist Franz Relo, as he was the first to study in detail the properties of the resulting triangle and apply them in his inventions. However, the geometry of the Reuleaux trianglewas used in the form of windows in the construction of the Church of Our Lady in Bruges in the 13th century. At the beginning of the 16th century, Leonardo da Vinci depicted a “map of the world” on four Reuleaux triangles. This figure is found in his manuscripts and in the Codex Madrid. In the XVIII century, a triangle of equal arcs of three circles was demonstrated by the famous mathematician Leonhard Euler. In 1916, an English engineer working in the USA, Harry Watts, developed and patented a cutter for square holes in a "floating" chuck.
Watts drill features
A unique invention makes it possible to obtain holes of almost regular shape: the corners of the square are rounded with a small radius. The raw area of a square hole does not exceed 2%. A distinctive feature of the Watts triangular drill is that when rotated, its center describes arcuate ellipsoid curves, and does not stand still like a traditional twist drill. The vertices of the triangle during this movement draw a square with parallel perfectly even sides. The chuck for such a cutter has an original design that does not interfere with movement.
Square hole drill structure
When drilling holes, chips are generated, and the cutter must have grooves to remove them. The profile of the working part of the Watts drill is a Reuleaux triangle with three halves of ellipses cut out of it.
This design with chip evacuation grooves solves 3 tasks at the same time:
- Drill inertia is reduced.
- The load on thespindle.
- Increases the ability of the drill to cut.
Usually square holes are made on lathes or milling broaches. The drill for square holes is fixed by the machine chuck with a special adapter. For domestic use of a square cutter, manufacturers offer overhead frames that connect to the cardan chuck and impart eccentric movements to the cutting tool. The depth of the hole corresponds to the thickness of the frame.
Today, high-quality drills that work quickly and for a long time are made from high-alloy steel grades. In their composition, such alloys contain more than 10% alloying additives, such as tungsten, chromium, vanadium and molybdenum. Different percentages of elements and a variety of steel hardening methods form alloys that differ in hardness, toughness, impact load resistance, cost and other characteristics.
Metal drills are the most widely used electrical consumable for several reasons:
- Metal products most often need holes for fastening: threaded connections, rivets and other types of connections.
- Metal drills can also be used when working with softer materials, such as wood.
- The production technology of this type of product is similar to the principles for the production of drills for various applications.
In Russia and many other countries, drills are in greatest demandfrom high-speed steel grade R6M5, which contains tungsten and molybdenum. The strength and price of products significantly increase when cob alt is added to the alloy or drills are coated with cooling titanium-nitride spraying.
Types of drills for metal products
Metal drills are used to make holes in products made of bronze, cast iron, copper, steel of various grades, cermets and other materials. For drilling tough hard-to-cut steel, high-strength products with the addition of cob alt are used. When working with twist drills, chips are discharged along two longitudinal grooves. According to the shape of the tail, such tools are divided into three types:
Metal drill with taper shank is inserted directly into the machine when used. Hex and cylindrical shanks require a special chuck.
Quality definitions by color
The quality of a drill for any material is determined primarily by its color:
- Black color tools have increased wear resistance, as they are processed with steam at the final stage of production.
- Heat-treated products have no internal stress, are highly resistant to high temperatures and do not deform when working with carbide steels. These drills have a slightly golden hue.
- The highest quality and durable have a bright golden color. They are coated with friction-reducing nitride.titanium.
- Regular untreated gray drills have the shortest life and the lowest price.
Working dimensions of metal drills are presented by modern manufacturers in a wide range. GOST provides for the division of such products into types according to certain sizes.
Metal drills are divided into several categories:
|diameter, mm||0, 3-20||0, 3-20||1-20|
GOSTs 4010-77, 886-77 and 10902-77 regulate the classification of drills by length and diameter.
How to choose a drill for glass or ceramics
Professional craftsmen have drills for every material in their collection: brick and concrete, metal and plastic, diamond drill for glass and ceramics. Glass is an extremely capricious material and requires the use of a high-quality and durable drill. Glass and ceramic surfaces can be processed with diamond-coated drills at the working end. The quality of such products is determined by the method of their manufacture. The thinnest and most inexpensive drills are made by electroplating. Stronger tools are produced by the powder process. They are distinguished by durability and stability. Relatively inexpensive high-strength drills with increased abrasiveness are producedmodern vacuum method.
To drill a hole in a glass surface, you need to have good skills. This long and painstaking process is carried out smoothly and slowly at maximum speed without pressure only with a diamond drill set strictly vertically. The hole must be constantly moistened with water for cooling. This action is more like scratching a hole with diamond grains.
If you have at hand the necessary tools and drills of the right size, any repair work will be carried out quickly and efficiently.