Diablo DSD1375S15 7/8 Inch - 1-3/8 Inch Step Drill Bit with 15 Steps is built for tradespeople who need clean, repeatable large holes in thin metal, PVC, and other plastics. This is a step drill bit designed for enlarging and drilling multiple hole sizes in thin materials with one accessory. Model Number: DSD1375S15. If you do electrical, plumbing, or HVAC rough-in and spend your day opening up panels, boxes, and light-gauge material, this bit is aimed right at that kind of work.

The big selling point here is range. Instead of carrying a pile of larger twist bits or hole-making accessories for every size jump, this bit covers sizes from 7/8 inch up to 1-3/8 inch across 15 steps. That makes it useful for field work where speed matters and the material is thin enough for a step bit to do its job well. Laser-etched step markings also make it easier to stop at the right size instead of guessing where to quit.

Diablo pairs that range with a 132 degree split point tip, and that matters more than it sounds. A split point helps the bit start where you place it instead of skating around on painted metal, galvanized surfaces, or slick plastic. In practical use, that means less wandering at startup, fewer ugly holes, and less time spent center punching or pilot drilling when the material and application allow it.

The grinding quality is another part of the story. Diablo calls out an automated precision CNC grinding process on each step to hold angle tolerances and reduce wear. On the job, that translates into more consistent cutting from step to step, less chatter, and smoother hole enlargement in materials where a rough-cutting bit would load up or fight you. The dual flute design also helps clear chips and keep the cut moving instead of rubbing and generating extra heat.

This bit is also built around modern cordless use. Diablo specifically positions it for corded and cordless tool efficiency, including high-speed mode, with claims of more holes per battery charge. Whether you are using a drill driver or an impact driver, the 3/8 inch shank with three flats is there to keep the accessory locked in more securely and reduce shank slip. That is a real-world advantage when you are leaning into larger diameters and do not want the bit spinning in the chuck.

Material-wise, it uses high speed steel construction. For the user, the important part is application fit: this is a metal and plastic hole-making accessory for thin stock, not a one-bit answer for thick plate. It is best used where step bits shine, such as sheet metal, electrical boxes, knock-out style enlarging work, plastic panels, and similar materials where you need control and multiple diameter options from one bit.

The overall size also makes sense for service work and punch-list jobs. With an overall length of about 3 inches and a listed weight around 0.5 lb, it is compact enough to keep in the bag without taking over a case. You are getting a single-purpose accessory that solves a very common problem: making larger, accurate holes quickly without constantly changing tooling.

Who should buy it? Electricians, plumbers, HVAC installers, maintenance techs, and serious DIY users who regularly work in thin metal or plastic will get the most out of it. If your jobs involve conduit openings, panel modifications, fixture installs, vent work, or enlarging existing holes cleanly, this is the kind of bit that earns its keep fast. If you mostly drill thick structural steel, this is not the right lane. But for thin-gauge drilling and hole enlargement, the Diablo DSD1375S15 step drill bit is a smart, work-focused option.

Diablo DSD1375S15 7/8 Inch - 1-3/8 Inch Step Drill Bit with 15 Steps Gets Right to the Sizes That Matter

This is a jobsite-friendly step bit for guys who need larger holes in thin metal and plastic without messing around with multiple accessories.

• Who it's for: Electricians, HVAC techs, plumbers, maintenance crews, and serious DIY users working in sheet metal, boxes, panels, and plastics.
• Why it stands out: The size range is useful, the split point helps it start clean, and the 3-flat shank is the kind of detail that matters once torque goes up.
• Worth knowing: This is the right tool for thin material and enlargement work. If you are planning to chew through thick steel all day, reach for something built for that instead.

• What size range does this step drill bit cover? It covers hole sizes from 7/8 inch up to 1-3/8 inch across 15 steps.
• What materials is it designed for? It is designed for thin metals, PVC, and other plastic materials.
• What chuck size is required? The minimum chuck size required is 1/4 inch.
• What type of shank does it use? It uses a 3/8 inch shank with three flats for improved grip and stability.