Starter Router Bit Set for a Hobby CNC: What to Buy First

A new hobby CNC usually arrives with a couple of generic bits and no idea which ones you'll actually need. This is the set I'd put beside a small machine, such as a 3018, X-Carve, Shapeoko or a BlueCarve, to cover signs, parts, 3D carving and the first aluminium job. Check your collet size first: most small machines run 3.175mm (1/8") or 6.35mm (1/4") shanks, and a trim-router spindle takes up to 6.35mm with the right collet.

The core five

1. An up cut for general cutting. A 2 flute up cut in 3.175mm is the workhorse for profiling and pocketing timber, MDF and plastic. It pulls chips out of the cut, which matters on a light machine.
2. A down cut for clean tops. A 2 flute down cut gives a splinter-free top face for lettering, shallow pockets and the show side of plywood. Use it for shallow work, not deep slots.
3. A V bit for signs. A 2 flute 90° V bit handles V-carved lettering, chamfers and most sign work. Add a 30° or 60° later for smaller text. See V-Bit Angles Explained.
4. A ball nose for 3D. A ball nose in R1.6 or R2 for relief carving, or a tapered ball nose for finer detail. See Ball Nose vs Tapered Ball Nose.
5. A single flute for plastic and aluminium. A 1 flute up cut for plastics, or the 1 flute DLC if aluminium is on the list. One flute takes a bigger chip with less force, which suits a light machine.

Worth adding early

• A surfacing bit to flatten your spoilboard so pockets come out an even depth. The ARDEN surfacing bit in 12mm or 20mm on a 6.35mm shank suits small machines. See the surfacing guide.
• A Z probe to set Z zero in seconds instead of eyeballing the tip. It's the most useful upgrade for a new machine.
• A compression bit once you cut a lot of plywood or melamine and want both faces clean. Start with the 2 flute compression in 3.175mm or 6mm.
• Spare collets in the shank sizes you use. A worn collet is the most common cause of chatter and broken bits. See the ER collet guide, or Makita trim router collets.

What to skip at first

Large-diameter TCT bits, 3 and 4 flute cutters and the industrial XB range all need more power, rigidity and feed rate than a small machine can give. A 3 or 4 flute bit run too slowly rubs instead of cutting, so it burns and dulls quickly. Stick to 1 and 2 flute bits in 3.175mm to 6mm until you know what your machine can handle.

Adam's Tip

Buy two of whichever bit you use most, usually the 3.175mm up cut. Small bits break, and a spare saves a job. Start with conservative feeds from the feeds and speeds calculator, take shallow passes, and increase from there.

Frequently asked questions

What router bits should I buy first for a hobby CNC?

A 3.175mm 2 flute up cut, a down cut, a 90° V bit, a ball nose and a single flute bit for plastics or aluminium. That covers profiling, signs, 3D carving and non-ferrous work.

What shank size does a small CNC use?

Most small machines use 3.175mm (1/8") or 6.35mm (1/4") shanks. Check the collet in your spindle or router and buy bits and spare collets to match.

Can a small hobby CNC cut aluminium?

Yes, with a single flute bit, shallow passes, an air blast and conservative feeds. A 1 flute DLC end mill is the easiest place to start.

Why do my small bits keep breaking?

Usually the feed is too high, the pass is too deep, the collet is worn or dirty, or chips are packing the slot. Take shallower passes, clean or replace the collet, and clear the chips.