Best Dado Bit for CNC Under $40 (2026): 5 Picks

Specs compared

Specifications are manufacturer rated, as published on each listing and collected 20 October 2026. “Not stated” means the listing does not give the figure.

What the listings tell you

We read five dado-capable bit listings for a home-shop budget. Two are true dado bits sized for dressed plywood, two are spirals (one upcut, one downcut), and one is a five-piece set of identical extra-long straight bits. Shanks split between 1/4 inch and 1/2 inch, and every bit here lists 2 flutes. Stated materials center on wood in its forms, hardwood, softwood, plywood, MDF, laminate and composites, with the SHARPRO also listing acrylic and aluminum.

One spec-table oddity: the Yonico 14323q title describes a dado straight bit for undersize plywood on a 1/4 inch shank, while its spec table lists a 0.71 inch cutting diameter that reads large for that job. Each review below notes where a listing disagrees with itself and follows the title and bullets.

Buying guide: best dado bit for cnc under 40

Match the shank to your collet

Two bits here list a 1/2 inch shank and three list a 1/4 inch shank. A 1/2 inch shank runs stiffer with less vibration, which shows in deep grooves; a 1/4 inch shank fits smaller trim-router collets. Buy the shank your machine already holds, not the one you wish it held; see our 1/4 vs 1/2 shank router bits guide.

Pick the cut direction for the job

Upcut spirals pull chips out of the groove for a clean bottom, which is what you want in a dado. Downcut spirals push chips down for a tear-out-free top surface, which suits visible edges and inlay pockets. Straight bits split the difference and are the classic dado choice. The Yonico pair and the SICWOOD set are straight dado bits; the SpeTool is upcut; the SHARPRO is downcut.

Size the bit to the plywood

The Yonico pair are sized to receive dressed plywood, which runs undersize of its nominal thickness, so the shelf fits the slot without sanding. If you cut mostly sheet goods, a dedicated undersize dado bit beats a standard straight bit every time.

Read the carbide and the build

Three listings name their carbide grade. The Yonico pair and the SICWOOD set state C3 micro-grain carbide, and the Yonico adds silver induction brazing on the tip joint. The SpeTool states solid carbide at HRC55 on a 1/4 in shank. A named carbide grade and a stated brazing or solid construction give you something to compare; a listing that names neither leaves edge life as a guess.

Cutting length decides the pass count

The SICWOOD set states a 2 in cutting length with a 1/2 in diameter, so deep grooves, dados and mortises go in a single pass. The SpeTool states a 1 in cutting length on a 3 in overall bit with a 1/8 in cutting diameter, and the SHARPRO states 22 mm of cutting length. In stock thicker than 1 in, the short bits need multiple passes while the 2 in SICWOOD cutters state they can finish in one; match the cutting length to the deepest groove you cut, and keep the extra stick-out as short as the collet allows.

Respect the stated RPM

The SICWOOD set states 16,000 to 24,000 RPM with a secure workpiece and steady feed rate. Extra-long bits like its 2 inch cutters want the rigid 1/2 inch shank they list and a firm hold-down; a long bit chattering in a loose collet is how edges go wrong. Run dust extraction, wear eye and ear protection, and keep the work area ventilated.

Project Match

• Bookcases and shelf carcasses: the Yonico 14323 and 14323q are sized for dressed plywood dados.
• Deep grooves and mortises: the SICWOOD 5-piece set lists a 2 inch cutting length for deep work.
• Clean groove bottoms: the SpeTool upcut spiral evacuates chips upward out of slots and dados.
• Tear-out-free surfaces: the SHARPRO downcut spiral pushes chips down for clean top edges.
• Several bits for one job: the SICWOOD set gives five identical bits to dedicate per material.

How the scores add up

Each bit is scored on performance, build, value, safety and warranty, with the weights published on our How We Pick page. None of the five listings states a safety certification or a warranty term, so safety and warranty score zero across the set; the ranking comes down to stated cut geometry, shank size, flute count and set value.

Scores run from 9.2 to 9.8: each product’s point total is placed on that range, so more points always means a higher score. Safety counts only for powered gear or where the listing states safety features; where it does not apply, the score is taken over the remaining 90 points.

FAQ: lasers and CNC

What is a dado bit?

A dado bit cuts a square-sided groove, called a dado, across the grain to receive a shelf, panel or divider. On a CNC it is usually a straight or spiral bit run at the right width and depth for the joint.

Why buy an undersize dado bit for plywood?

Dressed plywood runs thinner than its nominal size, so a standard 1/2 inch groove comes out loose. The Yonico pair are sized to receive dressed plywood, so the shelf fits the slot without shims or sanding.

Upcut or downcut for dados?

Upcut for the groove itself: it pulls chips out for a clean bottom. Downcut when the top surface must stay perfect, as in visible edges or inlay. Many shops keep one of each; this set includes the SpeTool upcut and the SHARPRO downcut.

What shank size do I need?

Match your collet: the Yonico 14323 and the SICWOOD set list a 1/2 inch shank, while the Yonico 14323q, SpeTool and SHARPRO list a 1/4 inch shank. A 1/2 inch shank runs stiffer in deep cuts.

Can these bits cut aluminum?

Only the SHARPRO lists aluminum among its stated materials, along with acrylic. The other four list wood and wood-like materials only, so keep those four to wood and wood-like materials.

More laser and CNC guides

Related: our best CNC router bits for hardwood under 25, the best CNC bits for inlay work and end mill vs router bit. Also see the CNC tooling hub and best CNC bit set for beginners.