Power Tool Accessories: Holesaws
Module four: Specialist Electrician's Tools
A hole saw is a saw that is in the shape of a circle. It is used in a drill to cut holes in thinner materials.
The main body of the saw is made from steel with a band of hardened high speed steel electron beam welded to the end, into which the teeth are cut (this is commonly known as Bi-metal construction). C.K Pro Cobalt range takes this construction one step further by incorporating 8% Cobalt within the high speed steel for increased performance, reliability and out put (PRO).
The teeth on the C.K hole saws are what is known as vari pitch – this means that the teeth have a variety of different pitches (see the saws module!). They are done like this to make them suitable for cutting through different materials such as steel, stainless steel, die cast metals, nail embedded wood, hardwood, softwood, plastics etc.
Slots in the side of the hole saws are provided for getting the slug of material out once the hole has been cut.
Hole saw collar screw sizes change with the size of the arbor, smaller hole saws (14mm – 30mm) use a smaller collar screw size, and can only be used on a smaller sized Arbor. Whilst the larger sized Hole saws (32mm – 114mm) need to be used with a larger sized Arbor which has locking pins.
Hole saws have to be used in conjunction with an arbor.
This screws in to the back of the hole saw and provides both the drive for putting in the drill chuck and the pilot drill which is used to keep the hole saw cutting in one place.
C.K Arbors are available in both hex and SDS drive formats.
The arbor can be unscrewed from the hole saw and easily attached to another size of hole saw.
it’s worth noting the drive pins on the arbors for the 32 to 150mm size hole saws.
These engage with holes in the back of the hole saw and provide the turning force for the hole saw. Without them the hole saw would tighten on the thread during use, to the point that it would be virtually impossible to get them apart again.
The final component of a hole saw assembly is a pilot bit. A pilot bit is an universal drill bit which simply locates the centre of the hole, and leads the way for the hole saw. Without the use of a pilot bit, it would be near impossible to locate the hole saw successfully and get a clean finish cut.
Pilot bits are usually hold in place via a grub screw, so when they eventually break or get worn out they can be easily replaced.