KUPA Thumbnails Chapter 11: How to Use Carbide Bits

KUPA's 10 Piece K-Star Carbide Bit Kit features bits for every salon need. Bits are available in gold or silver finish and come in a cylindrical container that displays each bit for easy organization.
KUPA Inc has the perfect guide:  Chapter 11 KUPA thumbnails is here
Chapter 11:  How to Use Carbide Bits 

The many sizes and shapes of bits available can be intimidating, but they’re all invaluable in the salon. Whether you’re new to e-files or just brushing up, this guide will explain the uses of each bit.


The only difference between the large barrel and the small barrel is the circumference, so nail techs can use either one according to their personal preference. Both can be used on nail enhancements for surface work, shortening the nail, or cutting a smile line when doing a backfill.

For beginners, it’s a good idea to begin with a fine grit small barrel bit, but as you get better you can move up to medium or coarse. For enhancement surface work, start with 10,000 RPM and move from side to side, using no pressure to remove product from the nail. This bit can also be used underneath the enhancement or to shorten the nail. If you want to work more quickly, you can slightly increase the speed.


The tapered barrel is like a cone, but with a flat top. It’s useful for going closer to the cuticle area because it’s tapered, making it easier to see where the e-file is going. Keep the bit parallel to the nail and lightly move it across the nail to clean the cuticle area, using 10,000 to 12,000 RPM and very light pressure. It can be used for surface work, cleaning underneath the nail, or to shorten enhancements as well.



The safety bit is a tapered bit with a rounded tip, making it very safe to use close to the cuticle area.

For beginners, it’s best to stay under 10,000 RPM or between 10,000 and 15,000 RPM. For beginners, this is the best bit to use to remove gel-polish. You can go closer to the cuticle area because you won’t cut the natural nail or cause damage to the surrounding skin with the rounded bit. If you use a regular bit without the rounded tip to remove product, the edge of the bit could cut into the nail if it’s tipped forward too much, causing a “ring of fire.” The safety tip is more forgiving because it’s rounded, so you are unlikely to cut with the edge.


Backfill bits are perfect for carving out a new smile line. Turn the speed up to 15,000 RPM when using this bit — this makes it easier to create a crisp smile line. Starting at one side of the nail, use the edge of the bit to carve out the smile line, then use the rest of the body to shave down the tip of the nail. The two week backfill bit has a smaller barrel, making it easier to remove a smaller amount of product for the backfill, while the larger four week backfill bit is designed to remove the right amount after four weeks of growth.


The inverted backfill tip is similar to the four week backfill bit, but it has a larger top and is tapered in the back, so some people find it easier to use. Because it’s larger on top, it’s easy to angle to carve out the smile line, using 15,000 RPM. Whether you use the inverted backfill tip or the four week backfill tip is a matter of personal preference.


The cone bit is a slim, longer tapered bit that’s great for use around the cuticle or sidewall because of its smaller size. It’s a good one for beginners to use to go closer to the cuticle area because the small, tapered bit makes it easy to see exactly where the file is going and not feel intimidated by the bit. It’s great to clean under the nail as well.


As well as cleaning under the nail, this bit is useful for small tight areas. It can also be used at a higher speed to pierce through nail enhancements to add nail jewelry or charms. When this bit is brand new, take a buffer file and slightly bevel down the edges so it’s not as sharp and intimidating to use underneath the nail.


The Easy-Off Mandrel Bit is a must-have for salon work. Fit a sanding band over it and use it for prepping nails to cut down your service time. Use the e-file very lightly and slowly, just enough to remove the shine. Move slowly toward the cuticle area using a fine grit sanding band. Because you’re using a fine grit at a slow speed, the band won’t remove too much of the nail surface or hurt the client.

This tool is also great for pedicures. Use a coarse or extra coarse sanding band and run the e-file at 10-12,000 RPM (or a little more if the client has a lot of thick calluses) to smooth calluses.

If you experience difficulty fitting tight sanding bands on the mandrel and struggle with removing them, or if you find the sanding bands too loose, the Easy-Off Mandrel is included in the 10 piece kit and can be bought separate if needed. It features small divots to securely hold the sanding band in place, as well as tapered edges near the base that allow sanding bands to easily slide into place and be removed without hassle.


Just like other metal tools, e-file bits should be sanitized with soap and warm water, then soaked in disinfectant for the manufacturer’s recommended time. After they’re done soaking, remove e-file bits from the disinfectant using tweezers and sanitize again with soap and warm water to remove trace chemicals from the disinfectant. Place them on a clean towel, dry them for up to 24 hours to remove all traces of water, and return them to the kit. Label your kit “clean” to follow state board regulations. Make sure all bits are completely dry before fitting them in your e-file — using a wet bit in an e-file can damage your handpiece, possibly voiding any manufacturer warranty.

PRO TIP: After sanitizing and disinfecting metal bits, they may be holding moisture that isn’t visible to the naked eye. We recommend allowing them to dry overnight to be sure all moisture has evaporated. If you use the bit too soon, fine dust will stick to the moisture and clog the bit, rendering it useless.

Kupa’s Ultrasonic Disinfector is small enough to fit on your manicuring table yet large enough to hold all your techtool implements, electric file bits, metal files, and more. The machine works with all EPA-registered disinfection liquids such as Lucas-cide and features ultra-sonic waves that will loosen trapped particles while the disinfectant sanitizes your implements.

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