Spot Drills, Jobber Drills, and Stub Drills: Understanding The Differences

Despite the fact that milling technology is able to produce accurate cuts in a wide range of materials, one of the most difficult challenges when machining can be drilling clean and accurate holes. To get the most out of your drills and get the best results for your workpiece, you need to employ several drills. By combining the use of multiple tools like spot drills to stub drills, you can achieve amazing results without having to worry about potentially damaging your workpiece.

If you are not familiar with drilling on milling machines, it may seem like a relatively easy task. Throw a bit in, program the spot, and drill the hole. While we wish it could be this easy, your average drill bit has a tendency to “walk” off its target, potentially resulting in disaster. This is because most drill bits have a relatively long cutting surface. At high speeds, this tool length results in the tools oscillating to the point that they can miss their target. In order to get the best results, several tools have to be employed.

Typically drilling on harder surfaces like metals requires spotting the holes to increase accuracy. Spot drills are the smallest and most simple drill bits. They feature a pointed end on a short shank and the tip is the extent of the cutting surface. The purpose of these tools is to create a small dimple at the drilling location. This dimple will help ensure that your next drill bitt find its mark easily.

Once the location of the hole has been properly spotted, machinists have options when it comes to the drill bits to use. The “traditional” drill bit length is known as a jobber drill, but shorter stub drills are a shorter option for increased accuracy. A stub drill is, as its name suggests, shorter than your average bit. This makes them a great option for drilling shallow and accurate holes.

If you need to drill a deeper hole, jobber drills are a great option. They have a longer reach and, with proper spotting, can be a very accurate option for drilling into any piece. Because of the risk of walking, it is wise to have both stub and jobber length drills in your shop so you can drill a wide range of hole depths.

No matter what drill bit style you need, construction is important. Metal tools are going to have a natural tendency to oscillate at high speeds. You can’t see with the naked eye, but the strain of fast rotation will cause your bits to flex and bend. One great way to limit this effect is to use tools constructed from carbide.

You might be thinking “but isn’t carbide a metal?” and you would be half right. Carbide tool stock is a combination of powdered ceramic carbide and a metal binder. The combination of these two materials creates a material with the strength of metal, but the edge retention and rigidity of a ceramic.

If you are looking for high quality carbide drill bits and milling cutters, you need to visit Online Carbide. Online Carbide is an American manufacturer of solid carbide end mills and drill bits. They grind all of their tools with 5 axis CNC grinding machines to produce incredibly accurate end mills, spot drills, stub drills, jobber drills, and more! If you have any questions about any of their carbide cutting tools, feel free to reach out to a member of the Online Carbide team by calling 630-238-1424 or emailing

For more information about Drill Bit Manufacturers and Best End Mills For Aluminum Please visit : Online Carbide.

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