We recommend using a specialised diamond core bit or glass and tile spade bit for these. These bits must be kept wet while drilling. You can also use a fresh and sharp standard masonry bit. Keep area wet while drilling with diamond bits

Boringoperation

For some manufacturers – especially those working in exotic materials – consistency is everything. After they have performed numerous operations on an expensive part, the last thing they want is to ruin it on the very last process.

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3M's metalworking time savings calculator helps calculate the value of the time you can save based on your individual shop rate.

Reamers also have an extremely predictive tool life. A machinist using an air gauge to measure parts throughout the manufacturing process can see when it’s nearing time to change the tool and put in a new one before a problem arises. Then, once the reamer is changed, the new reamer will produce a good hole on the very first part.

This is when you need to drill holes smaller than your fastener. To use our M12 example again, if you were using a large M12 coach-screw, then you would drill a pilot hole of 10mm to 10.5mm.

Boring tools and reamers have completely different designs. A boring head is an adjustable tool that consists of a cartridge with an insert. The advantage of this design is that it offers flexibility to use one tool in multiple operations or on different sized parts. This flexibility is often perceived to make the tool more economical, but because the inserts wear – which then leads to inconsistent holes sizes – this type of system can actually result in higher end costs.

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These are designed for clearing short holes through timber quickly. Available mostly in larger diameters, they are used for running holes through framing for plumbing and electrical cables. Both bits have a sharp positioning and starter tips with the larger cutting section behind. Spade bit

These bits look more like a router bit than a drill bit. They are designed for creating holes with flat bottoms. For example, when fitting dowels in furniture or concealed hinges in cabinetry.

Designed specifically for use with impact drivers, these are designed to withstand percussive force emitting from the drivers.

Reaming operationexample

In situations where you need to drill through your material, the bit should be at least 10mm to 20mm longer than the material thickness. This allows for the bit to cut a clear hole out the other side.

Reamingprocess in drilling

Reaming is also a good choice for materials that cannot withstand high levels of heat and therefore require slower machining and longer cycle times. When it takes four or six times to machine a part out of an exotic as a normal piece of steel, the cost in the part increases exponentially. With that much time invested, it’s important to have a fool proof method in place when the final operation of finishing a hole rolls around.

One of our automotive customers that runs 15 million of the same part per year had been using a boring tool to produce large holes and was frustrated with inconsistency. Holes that were undersized required additional handling to finish bore or hone to size. Holes that were oversized got scrapped. By switching to a reamer, the customer experienced more consistency and eliminated the need for secondary operations and waste.

Ideally, the length of the drill bit should be measured against the length of its fluted section, not including the straight shank section at its base. This helps to avoid the risk of your chuck spinning against and damaging the face side of the material.

Reaming operationsteps

These are used mainly to drill perfectly round holes. A cylindrical saw blade fits into a mount with a drill bit in the centre. It positions the saw and guides it through.Hole saw

A reamer, on the other hand, is a solid tool with a set dimension designed to deliver single digit RAs and micro finishes. It has a lead angle, a diameter, back taper, and a wiper area. On non-adjustable reamers, nothing on a reamer is moving, so it remains consistent and delivers the same hole size throughout the life of the tool. It also does not require replacement of inserts or adjusting by the operator to bring it back to size – which is subject to human error.

ReamingTool

In this episode of Metrology Training Lab, we discuss Calibration, which is critical to maintaining the quality and accuracy of your measuring equipment and what it means to calibrate your tools.

These come in a variety of forms. The basic ones are mainly used to drill wide holes for screws that sit flush with the surface. Others have an integrated pilot drill so that you can both pre-drill and counter sink.

Very short bits designed specifically for use when pre-drilling metal for riveting. Their diameters are matched to rivet sizes. Some are also double ended.

These can easily be drilled with HSS bits. However, it is advisable to run your drill at a lower speed. A fast drill can heat up and melt the material, resulting in swarf melting and sticking onto the material you are trying to drill into.

Adam has shared a series of tips for drilling in our Best Advice section. The Bunnings Workshop community team has also shared these useful guides as part of our tools series:

Choosing the right drill bit plays a huge role in making your drilling project is a success. It can help you use your power drill efficiently and safely.

These bits have a sharp position tip and raised cutting spurs on the outside edge of the flutes. They are designed for clean cutting when making furniture, or other similar projects.

It is also important to know the hole diameter you require for your project. This determines the type and size of bit you will need.

These bits have tiered cutting stages. They are designed for cutting accurately sized holes through materials such as thin sheet metal, plastic, aluminium and fibreglass.

Reaming operationPDF

If you only need to drill about 30mm into a material, then use a bit that has extra fluted length. It is good practice to drill holes a little deeper than needed, especially in masonry. In these situations, drill swarf can fill the hole and reduce its depth.

A masonry bit should be used for these materials. In most cases, we recommend using a hammer drill on hammer setting to aid the drilling process. Note that if drilling tiles, hammer setting might crack them. For very dense igneous rocks like granite or basalt, you may need to use specialised drill bits.

Tappingoperation

This hole is the correct size for your fastener to snuggly pass through. For example, if you are using M12 bolts, you ideally want a hole slightly larger than the M12 (12mm) bolt to avoid having to hammer it through. A 12.5mm or 13mm bit is ideal.

These are used when a long hole is needed to be drilled through timber. For example, when you may need to run cables, pipes or cyclone rods through framing, floorboards and bearers or joists.

There may be times where you have to drill through multiple layers of materials. For example when wall framing, you may have to drill through tile and compressed cement sheets. We recommend using a multi-material or construction bit. These are designed for drilling through a range of tile, masonry, timber and metal materials.

Reducing scrap becomes especially important when working with very expensive materials. In the aerospace industry, for example, manufacturers often produce lower quantities of parts out of Inconel®, titanium and other high-cost materials. For these manufacturers, using a non-adjustable reaming tool and changing it out more frequently can provide consistent hole sizes throughout the life of the tool and significantly lower scrap ratios.

Reaming operationon lathe machine

Unlike a finish boring head, which usually has just one tooth, a reamer will have up to 10 teeth depending on its size. Multiple teeth enable users to use much faster feed rates, and therefore increase productivity over machining with a single tooth tool.

Holemaking is one of the most common metalworking operations. It’s a critical operation that requires matching the right process with each job to maximize profitability. Boring is often considered the go-to method, but more manufacturers are finding reaming to be a better option in some high volume or high-cost part applications. Here’s why:

The bottom line is that reaming offers the big advantage of consistency. Whether you are producing high volumes of parts or small batches of high cost parts, reaming can ensure the process stability and repeatability you need.

However, there are many types of drill bits available, and it can be tricky to work out which one you need for your project.

Modern abrasive grains and stronger bonding methods found in the latest non-woven abrasives enable shops to quickly achieve desired surface quality.

The Bunnings Workshop community is here to assist if you need a hand in choosing the right drill bit for your project. Don't hesitate to hit the Start a discussion button and let us know your needs.