There are many challenges one must face when drilling holes in our workpieces. Especially if they´re made of hardened materials or are particularly expensive and we can’t afford to scrape them due to small miscalculations.
Drill bits are specifically designed to plunge into your piece and apply extreme vertical forces while efficiently removing material. However, centrifugal forces caused by high-rotating speeds might reduce the overall accuracy of your tools. There are some physical properties that can amplify uncertainty in this regard.
Steel tools, for example, tend to provide excellent sharpness but are also very flexible. This means that, when driven at high RPM, steel drills tend to wobble off their center, causing them to miss the target. Even if the tool’s entry point is off by a small fraction of an inch, it might cause problems when the piece is finally assembled into a system. Moreover, the whole drilling angle might be off too, causing misalignment problems and low-quality pieces.
Tool “wandering” is another issue many of us face when plunging our tools into our workpieces. This is mostly caused by tool deflection as it engages the material. Your tool might bounce off and twist away from your desired mark as it struggles to grip the surface. As it happens with wobbling, a “walking” drill might make you miss the mark and start a hole in an undesirable angle that will be hard to correct down the road.
In order to prevent these common problems, your best bet is to add spot drills and carbide bits to your tool belt. Carbide spot drills will solve accuracy problems in two ways.
Added Rigidity
Unlike steel and other metallic alloys, carbide tools offer little flexibility. In fact, they´re extremely rigid making them one of the hardest materials known. As a result, spot drills and carbide tools are more accurate, even at high speeds, making it easier for machinists to stay on target and match the blueprint.
Solid Starting Point
Before driving down your drill bit into a piece, it is always better to punch a pilot hole to guide your tool. This way, you create a small depression or cone-shaped dimple that “centers” your drill bit´s point and does not allow it to wander off.
Spot drills have a very specific geometry. They usually show a tankier length/width ratio that provides the extra stability you need to stay as close to the true center as possible. They don’t usually feature flutes beyond their cutting surface as they are not made for removing much material. Their job is to quickly and accurately find purchase and leave a perfectly made notch that keeps your drill bits or jobbers in place when they start drilling.
However, not every spot drill works the same. As I mentioned before, spot drills and carbide go hand in hand as this super material increases accuracy due to its hardness. Carbide is also more resistant and can be driven at higher speeds, allowing you to drill more holes per minute without breaking a sweat. Moreover, you need to consider point angles when driving pilot holes.
Using a drill bit with an angle that is narrower than that of your follower can cause problems. If the resulting hole is too narrow for your drill, the edges will provide an extremely small point of contact and focalize tensile forces in a small area of its flutes. This can cause violent deflection and even tool chipping. So, make sure your spot drill has an angle that is equal to or greater than that of your follower.
If you have any questions about spot drills or carbide tools, you should check out Online Carbide. They are an American manufacturer specializing in supplying workshops and companies with high-end carbide tools for increased efficiency and productivity at lower prices. Reach out to a member of their sales team at sales@onlinecarbide.com.
