A step drill, also known as stepped drill bit, step drill bit or step bit, is a conical drill bit with increasing diameters step by step. A step bit can be made of steel, high speed steel and cobalt or carbide tipped for drilling holes through soft materials like aluminum, plastics and wood, and hard materials such as bronze, cast iron and steel.
Sometimes, step drills will be coated by Tin (titanium-nitride) and Tia (titanium-aluminum-nitride) which makes it harder and more durable to offer a longer service life.
Straight and Spiral Flute
The fluted shape, for chip collection and faster removal, can avoid overheating to extend the service life of the step drill.
Besides, if the chips can be removed over the flute quickly, the drilling process will also become faster. Between these two flutes, a spiral fluted step drill can remove chips better than a straight fluted one.
CBN (Cubic Boron Nitride)-ground
Cubic Boron Nitride (in a cubic crystal structure) is a super hard material after diamond. With properties of superior thermal stability and chemical inertness, CBN is widely used for grinding cutting tools while diamond will deteriorates when contacting with steel.
As a result, CBN processed step drill has a better cutting performance by sharp flutes and split points.
Chamfer Edge (bevel edge)
When reaching the desired hole size, the chamfer edge (the transition of two steps) is used to make a smooth and burr-free surface of the cutting hole.
As all steps have the same step chamfer angle, the transition between the current step and the previous step is hard to notice.
The step height determines the thickness of the workpiece which a step drill can create a straight hole in. All materials you are going to drill should be thinner than the step height of the step bit you use.
In addition, each step height corresponds to a diameter with a laser etched markings for easy identification.
3 Flat Shank and Hex Shank
3 flat shank fits in any portable drilling machine (manual type) and pillar drilling machine while hex shank can also fit in automatic portable drilling machine without the need of screwing.
What is a Step Drill used for ?
A step drill is used for Drilling a hole or Enlarging an existing hole in thin materials, especially for thin sheet metal.
Not solely drilling, a step drill also has the ability of chamfering and deburring the cutting edge of workpiece by using the bevel of the next step. Therefore, step drill is a good choice for one-step drilling operations.
[ Application of Step Drill ]
For Thin Materials (up to 4 mm)
Metal, Stainless steel, Cast iron, Aluminum, Copper, Bronze, Fiber glass, Plastic, Acrylic, Wood.
Industry and Career
Mechanical engineering- panels and covers, switching systems
Automotive industry - chassis
HVAC (heating, ventilation and air conditioning) system
Electrician - electrical boxes, project enclosures
Glaziers -fiber glass
Carpenters -wood, plywood, particle board
[ Advantages of Step Drill ]
Convenient (one tool for various holes)
Due to the feature of multiple diameters of the step drill, you can drill holes of different sizes by carrying just one step drill bit, or two if larger holes are needed, rather than several twist drills.
Besides, a step drill is suitable for making holes in wood, plastic, metals and other materials.
Clean (smooth and burr-free)
By the CBN-ground sharp cutting edges, step bits can create smooth-walled and straight hole sides in the workpiece. The finished hole is burr-free and clean by the chamfer edge design for each step.
Fast (no need to change drill bit)
As there is no need for a pilot hole or to switching between many twist drill bits, the step drill can shorten the cutting time of small holes.
Additionally, the straight and spiral fluted design helps the step bit cutting through material smoothly without grabbing and it also guides the chip to go out which lead to a faster drilling process.
Multifunction (drill, enlarge and chamfer)
In addition to the basic function of drilling holes, step drills usually are used for enlarging the original hole. While drilling to a desired diameter, you can chamfer the hole surface with the bevel of the next step.