Open Hours:8:30am-20:30pm
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Applicable Materials
Granite, quartz, engineered stone, marble and quartzite
Certifications & Credentials
CE Certified · ISO 9001:2015 · Industry Standard Drafting Participant · 120+ Countries & Regions Served
Clean internal cutouts, holes, and inner radii on CNC
Quartz and engineered stone often chip at the rim when you adjust faucet/drain openings or clean up drilled holes. Use the finger bit for controlled hole sizing and truing on CNC machines. Water-feed cooling supports wet milling, while selected diamond grit and bond grade keep the diameter cutting consistently. Expect smoother hole walls and a cleaner edge for fittings, faster polishing, and fewer rejects from over-breakout or heat marks.
Quartzite is very hard, and inside corner radius work around sink or cooktop cutouts is a common stress point for cracking. Center water feed improves cooling during wet milling, and the diamond grit plus bond options help maintain steady stock removal on tough stone. A stable body reduces vibration on curved toolpaths and inner radii. Shops can hold target radii more reliably, limit chipping, and keep tool life and cycle time more predictable on hard-stone jobs.
Marble cuts easier than granite, but internal curves can show scratches, bruising or chatter marks if slurry loads up. Running wet with center water feed helps evacuate slurry and control heat on CNC machining centers. Matched diamond grit and bond choice keep the bit cutting smoothly through internal profiling and curve milling. You achieve cleaner internal contours with less hand blending, improving surface finish and speeding up the next grinding/polishing steps.
After sawing or rough routing, cutouts may have steps, tool marks and small chips that slow the finishing line. The finger bit performs controlled stock removal to true the internal profile on CNC routers. Water-feed cooling supports wet cutting, while diamond grit and bond options help avoid overheating and edge blowout. Profiles become more consistent, polishing time drops, and repeat countertop orders run faster with fewer touch-ups and reworks.
The DINOSAW diamond finger bit is a CNC internal-milling tool: it plunge- and side-mills sink cutouts, enclosed openings and programmed inside radii in stone countertops — where core bits drill round holes and blades cut straight, the finger bit completes the internal contour.
Seven diameters from Φ10 to Φ35 mm cover the internal milling spectrum: larger diameters rough fast at generous radii, smaller diameters reach tight corners.
Working heights from 15 to 100 mm cover thin counter slabs through thick profiled edges in a single pass sequence.
Water feeds through the bit center to the cutting face: at the bottom of a deep cutout, external spray cannot reliably reach — center delivery is what cools the actual working zone.
1/2" GAS (male), 5/8"-11 (female) and M14 (female) joints cover common CNC spindle interfaces — direct mounting protects the contour accuracy.
Applicable materials: Granite, quartz, engineered stone, marble and quartzite.
Typical machines: CNC stone machining centers cutting sink cutouts, faucet and drain zones, internal curves and cutout cleanup.
Actual bit life varies with material hardness, cutout depth, feed rate and water flow.
Finger bits are offered at Φ10, 12, 16, 20, 25, 30 and 35 mm with working heights 15–100 mm, in joint options 1/2" GAS (male), 5/8"-11 (female) and M14 (female) — matched to common CNC spindle interfaces.
| Type | Diameter (mm) | Working Height (mm) | Joint |
|---|---|---|---|
| Finger Bit | 10 / 12 / 16 / 20 / 25 / 30 / 35 | 15 ~ 100 | 1/2" GAS (Male), 5/8"-11 (Female), M14 (Female), etc. |
Four engineering decisions behind the finger bit range. The numbered points on the bit diagram correspond to the systems below.
A cutout job follows four steps: clamp the slab and zero the spindle over the cutout center, rough the opening with the largest suitable bit at programmed step-downs, finish tighter internal features with a smaller diameter where the design requires, then break the core free and clean the edges — water flows continuously through the bit.
Finger-bit geometry lets the CNC plunge and side-mill inside a closed countertop outline: internal curves and enclosed cutouts are milled directly, where a circular blade alone cannot complete the geometry — the finger bit finishes what the blade starts.
Water reaches the bottom cutting zone through the bit center, where external spray cannot reliably reach during deep milling: center delivery cools the actual cutting face, evacuates slurry from the kerf, and extends bit life at the depth where the work is hardest.
Inside corner radii are milled to the programmed radius directly: the cutout finishes at the CAD geometry without the corner cleanup that blade-only rectangular cutting leaves behind — cutout quality becomes a machined feature.
The diameter ladder follows the cutout logic: use the largest diameter that fits the required minimum internal radius for faster roughing, and step to smaller diameters where the CAD demands tighter inside corners — a typical sink cutout runs one large bit for roughing plus one small bit for corner finish, depending on radius and cycle strategy.
Long working heights are designed for the lateral loading that side milling generates: a finger bit works under side forces very different from a straight drilling tool, and the shank and working section are built for those forces at depth.
Three thread standards cover the CNC spindle fleet: 1/2" GAS, 5/8"-11 and M14 interfaces mount directly, protecting runout — and the contour accuracy that depends on it.
A process comparison for sink cutout production.
DINOSAW is a manufacturer of CNC stone processing machinery, specializing in diamond wire saw machines and CNC stone cutting equipment. With more than 20 years of R&D and manufacturing experience, DINOSAW contributes to industry standards including T/CMES 41001-2025 for CNC wire saw machines, holds 100+ technical patents, and supplies equipment and technical support to customers in 120+ countries and regions. Its manufacturing and management systems are certified to ISO 9001, ISO 14001 and ISO 45001, with CE-compliant machinery for international markets.
DINOSAW provides bit selection per machine and cutout program, with batch supply for CNC fabrication shops.
Match thread to CNC spindle before ordering.
Center feed requires through-spindle water delivery.
DINOSAW supplies roughing parameters per stone class.
Common Questions About Diamond Finger Bits
Because the cutting zone at the bottom of a deep cutout is where every stress concentrates — and three operational factors usually stack there. Water starvation: surface-applied water wicks away before reaching the cutting face at depth; if your machine lacks through-spindle delivery, the bit runs dry exactly where it works hardest. Step-down overload: taking too much material per plunge loads the bit's full working height at once; deep cutouts want shallow step-downs per the material chart so chips evacuate and heat dissipates. Side-loading at corner exits: exiting a radius with the spindle still feeding sideways snaps diamond edges — ramp out of the radius before the traverse. If bits wear evenly but fast, check water delivery first; if they chip at the crown, check the exit paths. Center water feed and disciplined step-downs typically extend deep-cutout bit life by a wide margin.
Start from the required minimum internal radius, not the cutout size. The largest diameter that fits the tightest radius in the design roughs fastest and wears slowest — a sink body with generous corners runs a Φ25–35 mm bit for the bulk of the cut. Where the CAD demands tighter inside corners — drain zones, tight back corners, fixture notches — step down to Φ10–16 mm for those features only. Most cutout programs therefore run two diameters: one for the fast roughing pass, one for corner finish. Programming the roughing pass with the big bit and leaving small-radius cleanup to the small bit cuts cycle time against single-bit programs. Send the cutout drawing or CAD file with the inquiry, and DINOSAW returns the diameter pair with the step-down parameters per material class.
It can open and enlarge holes, but round-hole drilling is the core bit's job, and the division keeps both tools efficient. A core bit removes a clean cylinder at high rate with a dedicated drilling action — the right tool for faucet, drain and anchor holes. A finger bit mills contours: it opens and cleans internal shapes, enlarges openings along a programmed path and finishes radii — work a core bit cannot do. If a job needs a plain round hole, reach for the core bit; if it needs the hole merged into a contour, or the contour itself milled, the finger bit earns its place. Shops running both keep the programs separate: core bit operations in the drilling cycle, finger bit operations in the milling cycle — two tools, two actions, no overlap. The pairing question comes up often enough that DINOSAW specifies them together for new cutout programs.
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