Hole saws are cylindrical cups with a serrated edge to cut various sizes of holes in a variety of materials. The serrated edge is designed to cut the hole; the other end is designed to be driven by an arbor or drill chuck. There is a wide variety of hole saws available in the marketplace, from inexpensive carbon steel hole saws to extremely specialized, application driven hole saws. The most commonly used saw, however, is the bi-metal hole saw.

Advantages of Bi-Metal Hole Saws

Most users prefer a bi-metal hole saw for the majority of their work because it is compatible with a wide variety of materials. It also cuts faster and smoother and with reduced vibration due to the variable pitched teeth.

Hole saws have two different types of steel joined together to form the edge of the cutting end of the hole saw. High speed steel is joined to a soft spring steel to form a durable edge that will cut a multitude of materials and help provide long life. High speed steel is used on the outer edge due to its wear resistance properties and forms the cutting edge of the teeth. Soft, spring steel creates a flexible backing material that allows the hole saw to absorb impacts of the job of drilling holes in difficult-to-cut materials.

A good bi-metal hole saw will easily cut through softer materials, such as plastic and wood-based items, as well as harder materials, such as steel and stainless steel. The type of high speed steel chosen by the hole saw manufacturer will contribute greatly to the performance of the hole saw. The best bi-metal hole saws will be made with high speed steel that has a high percentage of cobalt content.

More important to users is the life they will get from their bi-metal hole saw, or how many holes they will be able to cut before needing to replace it. In addition to using high speed steel with cobalt, the heat treatment process used by the manufacturer will impact the life expectancy of the hole saw.

One common frustration users have with cutting holes with a hole saw is removing the plug, or slug, from the cup after the cut is complete. Look for slots that are accommodating to easily work the plug from the cup.

Tips on Arbors and Pilot Bits

Cutting a hole with a hole saw requires the use of an arbor and often a pilot bit. Arbors, also called mandrels, are designed to connect a hole saw to a drill chuck as well as hold the pilot bit. They are made from hardened steel and alloy steel components for long life, as they need to last through multiple hole saws. Arbors connect to the hole saw with a thread in the cap of the hole saw. Hol”-18 thread drives hole saws 1-1/4″ and larger. The larger hole saws (1-1/4″ and larger) also have drive pin holes in the cap which receive drive pins from the arbor to facilitate quick and easy changes of the hole saw. Smaller hole saws connect to the arbor only with the thread and often get locked onto the arbor requiring tools to remove the hole saw.

There are quick-change systems in the market to help with quickly changing small hole saws on the arbor without the use of supplementary tools. The best sawing systems are universal. They will operate as a quick-change system with any brand of hole saw. Also, look for systems that don’t require the use of any proprietary components or adapters to operate. These adapters often lock onto the hole saw and may require the use of tools to remove the hole saw and may not deliver the tool-free changes you are looking for.

Pilot bits take most of the punishment in hole saw drilling. Many users drill with some oscillation movement to help clear chips from the cut. This puts a lot of side pressure on the pilot bit.

When drilling holes with a hole saw, you need a complete system designed to deliver the performance you need to do the job. This means all components of the system, not just the hole saw, need to provide you with durability and performance. When you choose the right system, you’ll find that cutting holes has never been easier.

If you need more information or choice of hole saws, welcome to check out K&W Tools Co., Ltd. – the company has specialized in kinds of metal cutting saws and woodworking saws for years. To get more details of metal hole saws, please do not hesitate to contact with K&W.

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