Step drill bits for metal

GRAFF special drill bits for drilling holes of large diameters (up to 40.5 mm) are intended for performing work mainly with sheet materials made from metal or plastic tin. When performing work, one requires the use of coolant.

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Useful information:

For processing base metal with thickness up to 4 mm, special drill bits are required. They facilitate making precise holes. The capacity to replace whole sets makes them universal. The main peculiarities of such drill bits are high drilling speed without loss of quality, even when working with extremely thin material. Their sharp tip, which is typical for conical drill bits, ensures processing not only metal parts but also drywall, plastic, wood and other materials.

Advantages of step drill bits
These products provide the following positive characteristics:

  • Unlike their gouge or spiral analogues, step drill bits provide ideal cut.
  • One step drill bit is enough to make several holes with different diameters.
  • Perfect center drilling.
  • Such drill bits allow to process rather thin sheet material and cope with various metals.
  • Thanks to no need for changing a drill bit performance is accelerated and efficiency is increased.

The use of step drill bits allows to correct defects left by other tools. Besides, it is possible to expand holes to clearly fixed parameters. Functionality of step drill bits justifies their high prices. As a result, there is no need for purchasing various drill bits.
Using a conical drill bit, you can chamfer during drilling. It greatly saves your time when performing high volume of work.

How to choose a conical drill bit
It should be understood that a high-quality drill bit will hardly be cheap. In addition, the color of metal it is made from indicates the strength of the gimlet. Taking into account color, there are the following quality classes of step drill bits:

  1. Gray indicates the steel, which had not undergone additional processing. Products made of it are not particularly durable.
  2. Black proves quenching of the material with superheated steam. This slightly improves quality, while at the same time cost.
  3. Dark-gold drill bits are obtained after high-temperature tempering, which relieves excessive stress. This greatly improves product performance.
  4. Brightly golden tools have a wear-resistant surface containing titanium nitride. This is the most durable type of material, however, its cost is significantly higher than of other analogues.

Manufacturing of conical drill bits involves using various kinds of steel that differ in marking. The abbreviation HSS means that when performing high-speed work, the product doesn’t deform and lose performance characteristics. However, it should be taken into account that the market is full of numerous Chinese fakes. Their quality leaves much to be desired. Therefore, you should look at prices.

When choosing step drill bits, the following parameters should be taken into account:

  • Brand. Products of famous brands are distinguished by high prices and appropriate quality.
  • Diameter. It is selected according to the required characteristics. You should remember that such a drill bit is able to make holes from 4 up to 32 mm in diameter.
  • Safety conformance of material and tool.
  • Possibility of multiple sharpening.

There are two types of step drill bits:

  • Ones that can be resharpened.
  • Ones that work without resharpening.

High cost of the second type is thanks to its long service life. While meeting the requirements of operations manual, the cutting edge does not dull for a long time. Such drill bits should be sharpened by specialists. One who has not experience in doing it can damage a drill bit.

Guide to step drill bits
A sharpened drill bit ensures making high precision holes in metal with thickness up to 4 mm. Proper performance includes compliance with certain recommendations:

  • The place where you need to get a hole in should be marked with a center-punch mark.
  • A tool is held perpendicular to processed material.
  • Metal drilling operations are performed at low speeds, especially if large holes are to be drilled. When performing such an operation, it is recommended to use a screwdriver.
  • A drill bit is lubricated with a small amount of machine oil. This helps to lower operation temperature when drilling.

Observing these rules ensures a long service life of step drill bits even without sharpening. Having decided to purchase such a drill bit, you should remember that their cost is because of its multitasking, excellent quality and durability.