The Complete Guide to Hole Saws

The diameter of the hole created will depend on the rated width of hole saw you purchase. Usually these holes will be made in some form of sheet material - see the sections below for specific examples and applications - although hole saws can also be purchased at varying lengths/depths as well as different diameters. Buying a deeper hole saw bit may allow for clean circular cuts through even fairly thick materials (provided the drill in question is properly set up and specced to handle them safely, of course).

Many hole saws and hole saw kits therefore come with arbors or pilot drill bits pre-packaged as an extra feature, but almost all are compatible with standard arbors and other hole saw accessories if not. Other optional features found in certain types of application-specific hole saw bits might include:

• Diamond tips for use on ceramics and masonry
• Extra heavy-duty construction for tougher jobs or materials
• Carbide-tipped teeth for use on fibreglass, formica, galvanised iron etc.
• Extra thin kerfs (i.e. tooth thickness) for fast and easy cutting
• A raised shoulder around the base of the hole cutter, designed to help prevent overdrilling/breakthrough in cases where this isn’t the desired result

When dealing with different sorts of materials (including natural and engineered timbers, glass, plastic, ceramics and metal), you’ll most likely need to choose different types of hole saws - and often employ slightly different drilling techniques - in order to achieve the neat, clean-cut, professional-looking results you’re after. While collections of guidelines are seldom any match for hands-on experience in this department, there are some fairly universal techniques and basic user tips that all hole saw operators should bear in mind when approaching a new job.

Always make sure you’re using an appropriately powerful drill for hole cutting.

Cordless models can get the job done on thinner or softer materials, but you’ll require at least a 14V model.

You should never attempt to bore holes through masonry or heavier timber (anything over about 50mm) with a battery-operated drill.

Always equip yourself with suitable PPE safety wear before starting to use a hole saw.

As a minimum, this should always include suitable goggles or glasses, an appropriate dust mask for the material being cut, and good quality work gloves.

Never wear loose clothing - such as baggy sleeves or dangling jewellery - that could get snagged in the hole saw, and always tie back long hair securely.

Regardless of the material or surface you’re working on, never try to force the drill bit through any faster than it wants to go.

Gentle, consistent pressure is key to achieving a neat, perfectly round hole.

Always start off slowly and gradually increase rotation speed as you go.

Apart from the power rating of your drill, the main limiting factor in terms of hole depth will often be the specific design of the hole cutter, and in particular the way it’s set up to deal with the material being removed:

Ensure you cut directly down into the workpiece at an accurate perpendicular (90-degree) angle to the surface.

This is the best way to prevent binding and sticking of the hole saw, or even stalling/burning out the drill’s motor.

Be aware that going in at a slightly off-centre angle - or hitting a nail while drilling - can cause very sudden and violent binding/jamming of the drill when using a hole saw.

Check that the full perimeter of the hole saw cutting edge is making even contact with the work surface all the way around before you start drilling.

When making large-bore holes in most types of sheeting and solid materials, it’s always advisable to use an arbor or pilot hole of some kind, in order to prevent the hole cutter from skidding around on the surface during the initial stages of the cut.

Whether included as part of a hole saw kit or purchased separately, these pilot bits sit at the centre of the hole saw’s hollow cylinder, and are usually removable or adjustable (often with a suitable hex or Allen key provided).

They will generally extend anywhere from 10-30mm out beyond the open cutting end of the hole saw and may also incorporate an ejector spring mechanism for helping to jettison plugs of loose material build-up.

If you want to drill a hole clean through a workpiece, be aware that going directly from one side through to the other with a hole saw can create a lot of ‘blowout’ (material tearing) on the reverse side.

This is due to the width of the hole cutter bit, and the subsequently large amount of material being removed.

To counter this, a good technique is to wait until the arbor or pilot bit breaks through - then move to the rear side (if accessible) and drill back the way you came, to a depth of a few millimetres, using the pilot hole as a guide.

Once you’ve done this, return to the starting side and complete the full depth of the hole cut.

One common hole saw problem encountered on many job sites and DIY projects is needing to drill a larger hole in place of an existing smaller one - for example, when fitting a new halogen downlight of wider diameter than the previous model.

Consider using an accessory such as a dust cowl to cover the hole saw bit while in use and prevent excessive spillage of debris when boring out large holes.

These simple add-ons also help to protect the drill itself by stopping dust from directly entering the motor, especially when working overhead.

Dust covers and cowls generally work by accepting the shank of the arbor through a central hole, and flexing as you drill to allow better access to the work surface.

Once the hole has been drilled, all the dirt and debris is collected in the cowl for easy and tidy disposal.