A drill is an essential bit of kit for any custom work on a bike, as driving drill bits and hole saws require some sort of power tool. Drills can be classified into portable and fixed, and cordless and corded.
Portable drills are hand drills, which come in corded and cordless varieties. If you are purchasing your first drill, choose a reputable cordless brand.
With improving battery technology, cordless electric power tools are getting cheaper all the time. If you select any particular brand of cordless tools, logic suggests you stick with that brand for maximum utilization of the batteries and chargers.
Over time you can increase your collection of tools and the common battery. The biggest risk is the manufacturer making a significant change to the battery design, effectively rendering the entire range of tools obsolete within a couple of years.
This might be one reason for choosing a mid- or lower-range brand unless you’re a very heavy user and can accept the cost of upgrading your set if required.
Typical cordless drills on the market have a range of features but the common ones are most important. The chuck grips the drill or screwdriver bit; yes, they also be used for driving screws. The chuck will most likely be keyless, meaning no tools are required to tighten or loosen it.
There will be a switch to start the electric motor and control rotation of the chuck, clockwise or anti-clockwise. There will likely be a speed control, low speed and high speed. High speed is used for drilling. The trigger normally allows variable speed control; the farther it is depressed, the faster the drill rotates.
The power of a cordless tool is limited by the amount of electrical current the battery can supply. This is a function of the voltage. Eighteen-volt (“18V”) is common nowadays, though 36V battery packs are appearing on the market.
There is a closely related cousin of the cordless drill, the portable impact driver. In the context of motorcycle work, these are great for removing and installing bolts on the bike. These sometimes come as pair when purchased with a cordless drill of the same brand.
Mains powered portable drills are relatively cheap and have plenty of power for drilling holes on motorcycle projects jobs. In fact, they have so much power it is possible to do yourself some injuries. Drilling very large holes, say over 12mm diameter, can cause the drill to catch the metal as it breaks through, either turning the metal into a propellor, or giving your wrists a very large shock (this is also still a risk on the more powerful cordless drills).
In order to safely drill larger holes, a fixed drill bolted to a bench or the floor is a great addition to your workshop (known as bench or pedestal drills) and these are normally powered by mains electricity.
The workpiece can be clamped to the drilling machine’s table very securely and the motor torque – often amplified by a belt drive between the motor and the spindle – can do its work more safely than holding a powerful portable drill.
Bench/pedestal drills also improve accuracy during drilling. On thicker pieces of material they can help ensure that the hole stay vertical and does not become eccentric.
When switched on, they run at one constant speed, but speeds can be set via the belt drive. Some pedastal drills may have a gearbox rather than a belt drive which might permit faster speed changes. Alternatively, a variable speed drive might be fitted that allows the speed to be adjusted electronically via a dial.
The drills worktable is generally mounted on a pivot, and can be accurately adjusted up and down, perpendicular to the spindle or often at any desired angle. A vice (or the workpiece itself) can be clamped securely to the table.
All these factors contribute to safe and accurate drilling. These bench, pedestal or floor mounted drilling machines can often be had cheaply on the second-hand market. Even the very smallest versions are useful in the shop.
Drill bits and accessories
Regular twist drill bits are the common method of creating holes up to about 13mm or ½" in diameter. When purchasing drill bits, buy the best ones you can afford. Higher price generally means better quality steel which will stay sharper for longer.
Regular drill bits are typically made of high-speed steel. Special drill bits labelled as “cobolt” refers to an alloy steel containing the element cobolt. These are more expensive but suited to drilling harder metals such as stainless steel. Cobolt drill bits can execute the same drilling jobs as high-speed steel drill bits but a full set of cobolt drill bits would be prohibitively expensive. They can be purchased individually for specific jobs as required.
If you predominately work on American motorcycles – where you’ll find more imperial sized fasteners – purchase imperial high speed steel drill bits. If working on Japanese or European motorcycles, purchase metric. Buy both sets if you have cash to splash – it’s very handy having them at hand.
Drilling holes larger than 13mm or ½" presents some other challenges. Drill bits are available in larger sizes and can be purchased individually, but they can be expensive. You’ll also need to purchase a drill bit with a reduced shank – meaning the shank of the drill bit that fits in the chuck might be 12mm diameter while the cutting end of the drill is the size you need, such as 19mm.
If you’re only drilling larger holes in sheet metal (say, up to 3mm) then a handy tool is a step drill. A step drill is literally constructed of steps in fixed increments. An example might be 4mm diameter to 20mm diameter in 2mm increments. If you only need the larger sizes occasionally, a cheaper step drill is a great option.
Another option for larger holes in metal is a hole saw. A hole saw uses a common arbor that contains a pilot drill bit and you screw on the appropriately sized hole saw for the job at hand. The pilot drill bit, usually 6mm or ¼" diameter – follows your center punch or mark or a previously-drilled pilot hole, and the hole saw cuts the hole you want. Hole saws are reasonably economical to purchase, even for very large holes, say up to 60mm. You might buy a “starter kit” with the arbor and some common sizes, then you can add individual hole saws to the kit as the need arises.
Hole saws need to be driven quite slowly when cutting steel, they need lubricant, and really cheap ones will not cut steel for long, if at all. The big downside with a hole saw is accuracy of the hole diameter. Depending on the quality of the arbor and the hole saws, the concentricity of the arbor and hole saw and runout of the hole saw is critical. Even on higher quality hole saws, the 30mm nominal hole saw might drill a 32mm hole. Test on some scrap material to confirm before use.