Drill bit sharpening jigs for reliable point angles in every workshop

A dull twist bit can turn a clean Australian hardwood project into a ragged mess in seconds. Many woodworkers blame their technique when the real culprit is geometry. Point angle, lip relief, and web thickness all change the moment a bit touches a grinder wheel, and getting back to factory precision by eye alone is nearly impossible. That is where a sharpening jig earns its place on the bench.

A jig holds the bit at a fixed angle against the grinding wheel, removes the human wobble factor, and reproduces the original geometry bit after bit. For hobbyists working out of a garage in Geelong or a shared shed in Newcastle, the cost of a good jig is small compared to a fresh set of premium cobalt or carbide-tipped drills every few months. Sharpening also keeps packaging and shipping waste out of the bin, which matters to a growing number of Aussie makers who count carbon footprint alongside cost.

The most common standard point angle is 118 degrees, the workhorse geometry for general-purpose drilling in softwoods, plywood, and most construction timbers. Harder materials and metalworking call for a flatter 135-degree split point that resists walking and survives the abuse of stainless steel or dense Aussie hardwoods like spotted gum and jarrah. A sharpening jig lets you switch between these two settings with repeatable accuracy, so your bits stay matched to the job rather than drifting toward a compromise angle after every touch-up.

Before buying any accessory, it helps to know what you actually need. Some jigs are dedicated to twist bits between one and thirteen millimetres, while others also accept larger sizes, countersinks, and step bits. The choice depends on the drills you already own, the materials you work with, and how much time you want to spend at the grinder. Understanding the basics of point geometry is the first step toward picking the right tool.

Why point angle matters for clean, accurate holes

The point of a twist drill is not just a sharp tip. It is a precisely machined wedge formed by two cutting lips that meet at a defined angle, supported by a chisel edge at the very centre. When that geometry is correct, the bit shears a clean chip and ejects it up the flute with minimal heat. When it is wrong, the bit rubs, burns, or wanders across the surface before biting in.

Wood behaves very differently from metal, yet the same geometric rules apply. In soft pine or poplar, a steep 118-degree point slices fibres cleanly. In dense, oily Australian species such as blackwood or red gum, a slightly flatter point with a shorter chisel edge reduces the load on the cutting lips and prevents the bit from grabbing and splitting the grain. A jig makes the difference between these two setups a matter of minutes rather than guesswork.

Consistency is what separates a useful bit from a frustrating one. A bit that has been reground three times by hand will rarely cut the same size hole twice, and the diameter drift will show up as sloppy mortise fits or screws that refuse to seat properly. Holding every bit to the same factory angle with a jig restores uniformity across the set, so a 6 mm hole is a 6 mm hole whether you drilled it yesterday or last month.

Heat is another reason geometry matters. A dull or poorly shaped bit generates friction, which transfers to the workpiece, the shank, and eventually your hand. Sharpen correctly and the bit cuts cooler, lasts longer, and produces a smoother exit hole on the back side of a board. That is a quiet benefit, but anyone who has burnt a hole through a piece of figured jarrah will appreciate it.

Common jig styles for the home workshop

The most popular style is the drill bit sharpening jig with an adjustable angle block and a sliding carriage. The bit drops into a collet, the carriage moves past the grinding wheel, and the user sets the point angle using an indexed scale. Versions from manufacturers such as Darex, Drill Doctor, and a handful of European brands dominate the Australian market through specialty retailers and online importers.

A second style uses a fixture plate with pre-cut slots at fixed angles. The drill slides along the slot and presents the cutting lip to the wheel at a fixed geometry. These jigs are simpler, cheaper, and often machined from thick aluminium plate. They excel at high-volume touch-ups of small bits used for dowelling and box joints, but they lack the flexibility of a fully adjustable unit.

A third option is a fixture that mounts to a bench grinder and indexes the bit using a small wheel or cam. These hybrid jigs appeal to turners and machinists who already own a slow-speed grinder and want a single setup for drill bits, lathe tools, and gouges. They are heavier and costlier, but they share hardware between several sharpening tasks and earn their keep in a busy shed.

For woodworkers who only need to refresh the occasional bit, a hand-held guide with a ceramic rod or diamond hone can also work. It does not restore a true point angle the way a grinder-based jig does, but it cleans up the cutting lips in a pinch and is handy on remote jobs where power is unavailable, such as a fencing contract in the Hunter Valley or a remote deck build in regional Queensland.

Features that distinguish a good sharpening jig

• Indexed angle stops at 118 and 135 degrees with clear, easy-to-read markings
• A sturdy collet or clamping system that grips the bit without crushing the shank
• Adjustable bit projection so the cutting lip clears the wheel without flexing
• A stable base that bolts or clamps to a bench or grinder stand
• Replacement collets available for sizes outside the supplied range

Setting up the jig for 118 and 135 degree points

Most jigs arrive with the factory setting set to 118 degrees, the universal standard for general drilling. Confirming that setting before the first stone touch is worthwhile. Loosen the locking screw, rotate the angle block until the index mark lines up with 118, and snug the screw back down without over-torquing. A small error here propagates into every cut the bit makes afterward.

Switching to 135 degrees is a matter of releasing the same lock and rotating the block two increments further on most indexed designs. Some jigs use a continuous scale with a vernier pointer, which gives finer control and is useful for working with non-standard angles for plastics or thin sheet metal. Whichever style you use, always reset to a known reference and recheck the angle indicator before grinding.

Bit projection is the next setting to confirm. The cutting lips should clear the grinding wheel by just enough material to grind, with the chisel edge sitting just clear of the wheel surface. Too little projection and you grind the shank; too much and the thin web flexes, producing a curved lip that cuts oversize. Most jigs have a depth stop or set screw for this purpose, and a quick dry run with the grinder off is worth the extra minute.

Test the setup on a scrap bit before committing a favourite to the wheel. A cheap HSS bit bought in bulk from a hardware chain is ideal for the learning curve. Grind, inspect with a loupe or a magnifier headset, and adjust the angle or projection until the result looks symmetrical. Once the test cuts cleanly through a piece of radiata pine, the settings are locked in for the rest of the session.

Step-by-step sharpening routine

Begin with a clean bit. Wipe away any pitch, oil, or metal swarf with a rag and a little mineral turpentine, especially if the bit has been used on Australian hardwoods that leave a gummy residue. Secure the bit in the jig's collet, snug but not crushed, and align the reference mark with the existing point angle setting.

Dress the grinding wheel before each session. A diamond dresser or a star dresser trues the surface, exposes fresh abrasive, and removes any glazing from previous use. Hold the dresser against the rotating wheel with light pressure and traverse across the face until the wheel looks evenly grey. A sharp, clean wheel grinds faster and leaves a finer finish on the cutting lip.

Bring the bit into contact with the wheel using the jig's carriage or slide. Use light pressure and let the abrasive do the work. A single pass is rarely enough; three or four light passes produce less heat and a cleaner edge than one heavy pass. Pause between passes and dip the bit in water to keep temperatures down if the jig does not include a built-in cooling trough.

Flip the bit and grind the opposite lip using the same number of passes. Symmetry is the goal. After grinding, inspect both lips under magnification and compare their lengths. If one lip sits ahead of the other, add a single light pass to the shorter side until the two match. A final light stoning with a fine India stone removes the wire edge and leaves the cutting lips ready for work.

Useful items for a sharpening session

• A small cup of water for cooling the bit between passes
• A 10× loupe or optivisor for inspecting the cutting lips
• A diamond wheel dresser for truing the grinding wheel
• A rag and mineral turpentine for cleaning pitch from used bits
• A scrap bit reserved for setup trials and angle testing

Avoiding common sharpening mistakes

The most common error is overheating the bit. Excessive heat draws the temper from high-speed steel and turns a hardened cutting edge into a soft, blue-tinged one that dulls within minutes. Avoiding this is straightforward: light passes, frequent dips in water, and a clean, sharp wheel. If the bit starts to change colour, stop and let it cool before continuing.

A second mistake is grinding the chisel edge too aggressively. The chisel is the small ridge at the very centre of the point, and it does not need to be razor sharp. Reducing it excessively thins the web and weakens the bit. A light pass across the chisel with the corner of the grinding wheel, often called a chisel grind or a four-facet point, is enough to break the edge and improve self-centering without compromising strength.

Symmetry slips are another frequent problem. The eye naturally favours one side, and a slow drift toward one lip becomes a fast drift across an entire set of bits. A jig removes the eye from the equation, but a final visual check is still worthwhile. Lay the bit on a flat surface and look down the flutes from both sides. The cutting lips should appear as mirror images of each other.

Sharpening a bit that is past its useful life is the last common trap. Once the flutes are chipped, the web is cracked, or the shank is worn in the collet, no amount of grinding will restore performance. Retire the bit, drop it into the scrap steel bin, and replace it. Good jigs extend the working life of a quality drill, but they cannot resurrect a broken one.

Maintenance and storage after sharpening

Once a bit is sharp, a light coat of camellia oil or a thin film of rust inhibitor keeps it ready for the next job. Australian workshops along the coast, from Wollongong to Fremantle, often deal with humid salt air that finds any unprotected steel within a season. A small spray of protectant and a wipe with a clean cloth is a thirty-second habit that prevents hours of rework later.

Store sharpened bits in a dedicated block, index case, or foam-lined drawer. Bumping the cutting lips against each other or against a shelf dulls them almost as fast as drilling through abrasive material. Foam with pre-cut slots works well for a small home shop, while indexed metal cases suit a larger collection organised by size and type.

Keep a simple logbook noting when each bit was last sharpened, what angle it carries, and which materials it has seen. The data is surprisingly useful when a hole starts wandering or a cut runs hot, and it helps spot bits that are being sharpened too often. A bit that needs grinding every few jobs is usually a candidate for retirement rather than further attention.

For woodworkers who want a ready supply of fresh bits, drill accessories, jigs, and related tooling, the catalog at sloanwoodshop.com offers a curated selection that ships to hobbyists across the country. Pairing a quality jig with steady access to replacement stock keeps the workshop productive and the learning curve manageable, especially for those just discovering the satisfaction of a freshly ground cutting lip.