BIT SETS

Most beginners start with a small group of CNC router bits that cover the common cuts. That usually means an upcut or downcut endmill for cutouts and pockets, a V-bit for lettering and detail, a surfacing bit for flattening, and a ball nose bit for 3D work. Buying these as a router bit set is the simplest way to get started, since the set already covers the cuts a first project needs.

For cutting wood on a CNC router, a spiral upcut or downcut endmill is the standard choice. An upcut bit clears chips quickly and works well for pockets and cutouts. A downcut bit leaves a cleaner top edge on the face of the board. Both are solid carbide, which holds an edge in hardwood and plywood far longer than lower-grade steel.

The difference is the direction the spiral flutes move the material. An upcut bit lifts chips up and out of the cut, which keeps the bit cool and clears pockets well, though it can leave small tears on the top edge. A downcut bit pushes chips down, which leaves a clean top surface but packs chips into the cut. Many CNC users keep both on hand and match the bit to the job.

Use a compression bit when you need clean edges on both the top and bottom of the material at once. It combines an upcut spiral at the tip and a downcut spiral above it, so both faces stay free of tearout. Compression bits are a common choice for plywood, melamine, and laminate, where both surfaces show in the finished piece.

A ball nose bit has a rounded tip instead of a flat one, which lets it carve smooth curves and contours. It is the bit most people reach for when doing 3D carving, relief work, and rounded surfaces. Because the tip is rounded, it steps across the surface in fine passes to build up detail, so 3D carves take longer than flat cuts.

Shank size is set by the collet your router accepts, so check which collet size your machine takes before buying. A 1/4" shank is more rigid and suited to larger cuts and faster material removal. A 1/8" shank fits smaller machines and reaches finer detail. Many of our sets include both shank sizes with reducing collets, so you can run either size on one machine.

Burning usually means the bit is spending too long in one spot and building heat. The most common causes are a feed rate that is too slow, a spindle speed that is too high, or a dull bit. Raising the feed rate, lowering the RPM, and running a sharp solid carbide bit will normally clear it up. Our feeds and speeds guide and tool database give you a tested starting point for each bit.

A router bit set is usually the better starting point, since it covers the common cuts in one purchase and costs less than buying each bit separately. Once you know which bits you use most, you can add individual bits for specific jobs like deeper roughing or specialty profiles. For a first machine, a starter set gets you carving without guessing which bits to order.