Jobber Length Drill Bits

Jobber length drill bits are the most common type of drill bits used in general-purpose drilling applications. Their moderate length provides a good balance of reach and rigidity, making them suitable for a wide range of materials and tasks. This guide covers everything you need to know about jobber length drill bits, including their characteristics, materials, uses, and how to choose the right one for your needs.What are Jobber Length Drill Bits?Jobber length drill bits are characterized by their length relative to their diameter. They are longer than stubby or screw machine length bits but shorter than long or aircraft extension bits. This intermediate length provides a balance between drilling depth and bit stability, making them versatile for numerous applications.Defining 'Jobber Length'The 'jobber length' designation doesn't have a fixed numerical value but rather a proportional relationship. The flute length (the spiraled cutting portion) is typically 9 to 14 times the diameter of the drill bit. Overall length varies depending on the diameter.Materials Used in Jobber Length Drill BitsThe material of a jobber length drill bit significantly impacts its performance and suitability for different applications. Here's a breakdown of common materials: High-Speed Steel (HSS): A popular choice for general-purpose drilling. HSS bits offer good wear resistance and can be used on wood, plastic, and soft metals like aluminum. Cobalt Steel: Offers superior heat resistance compared to HSS, making it ideal for drilling harder materials like stainless steel and cast iron. Carbide: The hardest and most brittle option, carbide bits excel at drilling very hard materials like hardened steel and titanium. They require slower speeds and more rigid setups to prevent breakage. Black Oxide Coating: This coating is applied to HSS bits to increase wear resistance and reduce friction, preventing rust. Titanium Nitride (TiN) Coating: TiN coating provides even greater hardness and lubricity than black oxide, extending the life of the bit, especially when drilling abrasive materials.Uses of Jobber Length Drill BitsJobber length drill bits are used extensively in a variety of industries and applications: Metalworking: Drilling holes in sheet metal, pipes, and structural steel. Cobalt or carbide bits are preferred for harder metals. Woodworking: Creating pilot holes, drilling for screws, and boring holes for dowels and hardware. HSS bits are generally sufficient for woodworking. Construction: Drilling into wood, drywall, and some masonry materials (when used with appropriate drill modes). DIY Projects: Homeowners and hobbyists use jobber length drill bits for various projects around the house.Choosing the Right Jobber Length Drill BitSelecting the appropriate jobber length drill bit depends on several factors: Material to be Drilled: Harder materials require bits made from harder materials like cobalt or carbide. Softer materials are suitable for HSS. Drill Size: Choose the correct diameter for the hole you need to create. Drill Type: Consider the type of drill you'll be using (e.g., drill press, hand drill, impact driver). Some bits are designed for specific drill types. Coating: Consider the coating for the longevity of the drill bit.Jobber Length Drill Bit SizesJobber length drill bits are available in various sizes, typically categorized as: Fractional Sizes: Measured in inches (e.g., 1/16', 1/8', 1/4', 1/2'). Metric Sizes: Measured in millimeters (e.g., 1mm, 2mm, 5mm, 10mm). Number Sizes: A numbering system used to denote drill bit sizes (e.g., #1, #10, #30). These correspond to specific fractional inch sizes. Letter Sizes: Similar to number sizes but uses letters (e.g., A, B, C).It's crucial to use the correct size drill bit for the application to ensure proper hole dimensions.Tips for Using Jobber Length Drill BitsFollow these tips to maximize the performance and lifespan of your jobber length drill bits: Use the Correct Speed: Refer to a speed chart for the recommended RPM based on the bit size and material. Apply Consistent Pressure: Avoid forcing the bit. Let the bit do the work. Use Cutting Fluid: Lubricating the bit reduces friction and heat, especially when drilling metal. Clear Chips Regularly: Remove chips from the hole to prevent binding and overheating. Sharpen Dull Bits: Sharpening extends the life of the bit and improves drilling efficiency. Consider using a drill sharpener from Wayleading Tools. Store Bits Properly: Keep bits organized and protected in a case to prevent damage.Troubleshooting Common Problems Bit Walking: Use a center punch to create a starting point. Bit Binding: Reduce drilling speed and clear chips more frequently. Bit Breakage: Use the correct speed and pressure, and ensure the bit is properly aligned. Consider upgrading to a cobalt or carbide bit for harder materials. Burrs: Remove burrs with a deburring tool or countersink.Jobber Length Drill Bit SetsPurchasing a jobber length drill bit set is a cost-effective way to acquire a range of sizes. Look for sets that include a variety of fractional, metric, and number/letter sizes, as well as a durable storage case.Safety PrecautionsAlways wear safety glasses when drilling to protect your eyes from flying debris. Use caution when handling sharp drill bits and ensure the workpiece is securely clamped to prevent movement.Table of Common Jobber Length Drill Bit Sizes (Fractional) Fractional Size (inches) Decimal Equivalent (inches) 1/16 0./8 0./16 0./4 0./16 0./8 0./2 0.50 Data sourced from various drill bit manufacturer specifications.