What is a Step Drill Bit
Step drill bits are a must have in your toolbox. They are also referred to as cone drill bits, uni-bits, or multiple diameter bits. Because of the varying diameters of the bit, it is easy to drill various sized holes with the step drill bit. Most bits have metric increments such as 1/8”, ½”, 1-3/8”.
What is the primary use for these bits?
These bits are mostly used to drill holes into sheet metal or thin material where the hole size may vary. Other commonly used materials are plexiglass and thin pieces of wood such as plywood. Regular drill bits will warp these thin pieces of metal when drilling. Step bits have straight flutes unlike the angled flutes of a normal drill bit. The angles change the material while the straight flutes pass right along without affecting the material. Unibits are also effective on sheet metal. These are commonly used in metal fabrication, electrical work, plumbing, and automotive repair. If a range of hole sizes are required, step drill bits save a ton of time and effort since it eliminates the need to switch between different bits.
What type of step bits are there?
Carbide, black oxide, high speed steel, titanium. High speed steel or HSS bits are perfect for drilling softer materials such as aluminum or plastic.
How to drill a hole in sheet metal:
1. Cutting a hole in the piece of sheet metal will require you to use a bit with ¼” steps
2. Ensure that the thickness of the sheet metal you are working with is the same or less than the step height.
3. Marking the step where you will stop is important so that you do not drill too deep and make a hole larger than the desired size.
4. Using oil helps keep the drilling process smooth so lubricate the surface of the sheet metal
5. Drill the hole to the desired diameter
