Startool Drill Bit Guide: Shapes, Grit Codes and Which Bit to Use

By Edmond Lin, M1 Nail & Beauty Supply, Markham, Ontario. Last updated 8 October 2026. Shapes, codes and safety notes follow Startool's own product information.

Startool bits are named by shape and grit. The shape tells you the job: barrels reduce and shape product, Round Top barrels do the same with a safe rounded tip, the 3 in 1 and All in 1 combine several jobs in one bit, and the Shark is cut for gel polish removal. The grit, from Extra Fine to 5X Coarse, tells you how fast it cuts. Startool Inc. is based in Orange County, California and has made nail bits since 2009. Its carbide bits are for enhancement product only, never the natural nail.

Which Startool bit for which job

Every Startool shape at M1

3 in 1, All in 1 or Round Top?

All three are built to work close to the cuticle without cutting the skin, which is why they are the Startool bits most salons reorder. The difference is how much else the bit does.

The Round Top is a straight barrel with a smooth dome on the end. It reduces and shapes like a normal barrel, and the dome lets you run it along the cuticle line and side walls. Choose it if you already like a barrel and only want a safer tip. Round Top Large Barrel runs from Fine to 5X Coarse, and Round Top Small Barrel is the narrower version.

The 3 in 1 Special has three zones: a smooth top for the cuticle area, a tapered body that keeps the side wall in view, and a wider lower body that shaves and shapes product. Startool describes it as the version for short nails. 3 in 1 Special comes with a 3/32 in or a 1/8 in shank.

The All in 1 uses the same three zones on a longer bit, made so you can clean the cuticle area, shape, shorten, smooth and clean under the nail without changing bits. Startool describes it as the version for long nails. All in 1 is 3/32 in only, and the bits in our stock carry a colour band for each grit.

How to read Startool grit codes

Every grit family uses the same ladder. On the Large Barrel it reads STXF, STF, STM, STC, STX, then ST2X to ST5X. The other shapes change the prefix or add a suffix: a final "s" is the Small Barrel, "sp" is the 3 in 1 Special, R is the Round Top and A is the All in 1.

Shark bits are sold by grit name only, from Fine to 4X Coarse. Band colours are read from the All in 1 bits M1 has in stock.

Which grit to choose

• Extra Fine and Fine: finishing, smoothing the surface, thin layers of product
• Medium: everyday shaping and refining of acrylic, gel and dip powder
• Coarse and Extra Coarse: shortening and taking down acrylic, hard gel and dip powder quickly
• 2X to 5X Coarse: the fastest removal of thick product; use light pressure and a controlled speed, as each step up removes more per pass

A common salon setup is one Coarse or Extra Coarse bit for removal and one Fine or Medium bit for refining. For how grit works across carbide, ceramic and diamond bits in general, see our nail drill bit grit chart.

3/32 in or 1/8 in shank

The shank is the smooth rod that goes into the handpiece. 3/32 in (2.35 mm) is the standard for nail e-files. 1/8 in (3.175 mm) is thicker and only fits a handpiece or collet made for 1/8 in bits. M1 stocks the Large Barrel, Small Barrel, 3 in 1 Special, Cone under nail cleaners, Cuticle Taper and LOXO mandrel with a 1/8 in shank. On our Startool SKUs, numbers starting with 9 or 7 are 3/32 in and numbers starting with 8 are 1/8 in.

Carbide or diamond: what can touch the natural nail

Startool's safety notes are direct: carbide bits should never be used on natural nails, and they are for professional nail technicians wearing safety goggles and a mask. Carbide teeth shave product away, so keep them on acrylic, gel, dip powder and builder gel.

For the natural nail and the cuticle, Startool points to its diamond-coated bits. The Diamond Ball and Diamond Conical are coated with fine diamond particles and are described as usable on natural nails for cleaning and removing cuticle in a dry manicure or pedicure. For prepping the nail surface, a sanding band on a LOXO mandrel does the job, with a new band for every client.

How to clean and disinfect drill bits

Startool publishes this routine for its bit care system. It works for any reusable carbide or diamond bit:

1. Soak the bit in acetone to soften residue and debris.
2. Brush off any remaining material.
3. Wash with soap and water.
4. Rinse with clean water.
5. Pat dry with a new, clean paper towel so the disinfectant is not diluted.
6. Fully immerse the bit in disinfectant for the contact time on its label.
7. Pat dry again with a new, clean paper towel.
8. Store only disinfected bits in a clean, closed container.

Startool's instructions name an EPA-registered disinfectant because it is a US company. In Canada, use a disinfectant with a Health Canada DIN and follow your local public health rules. Wear gloves or use tongs when taking bits out of the solution.

Startool bit FAQ

Shapes, grit codes, shank sizes, cutting direction, safety notes and the cleaning routine are taken from Startool's product pages as of October 2026. Colour bands and the list of stocked bits come from M1's own shelves. The grit suggestions are common salon practice, not a Startool specification. This guide is for trained nail technicians.