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How to choose the right tool, the right speed, and keep the blade sharp
A machine can be as precise as you like — the result ultimately depends on whether the tool and cutting data match the material. The training regulations for machine woodworkers require that you can independently calculate cutting data and feed rates for optimal machining technique (goal 28 in the training regulations) and that you can make the correct choice of tool and machining data for complex tasks (goal 25).
Cutting speed is the speed at which the cut moves through the material and depends on the tool's diameter and revolutions. Feed rate is how quickly the workpiece or tool moves through the material. If cutting speed is too low, the tool grinds and burns the surface; if too high, the cut wears quickly. Too low feed gives the same burning problem, while too high feed gives ragged edges and overloads the tool.
For woodworking, tools are typically made in high-speed steel (HSS), hard metal (HM/carbide) or diamond (PKD). HSS is cheap and easy to grind but wears quickly, especially in materials with glue and harder fillers. Hard metal maintains sharpness significantly longer and is standard in industrial production. PKD tools (polycrystalline diamond) are used for the most demanding materials — for example particleboards and MDF with high glue content or very abrasive veneered boards — because diamond can withstand many times as much wear as hard metal.
| Tool material | Usually used for |
|---|---|
| High-speed steel (HSS) | Solid wood in smaller series; easy to sand yourself |
| Carbide (HM/carbide) | Standard tools for sheet and solid wood in series production |
| Polycrystalline diamond (PKD) | Very wear-prone materials like chipboard, MDF and laminate in large series |
The training regulations emphasise that at both the basic and the independent level you must be able to grind, use and maintain tools for manual and machine processing in accordance with the applicable Danish Standard (goals 7 and 27 in the training regulations). A dull tool presses on the material instead of cutting it, which gives a worse surface, more heat and an increased risk of the workpiece tearing loose from the clamping.
Cutting data for a given material and tool is often found as recommended values from the tool manufacturer, but the experienced machine carpenter adjusts them based on the machine's stability, the condition of the material and the desired surface finish. The ability to read the result — the sound, the chips and the surface — and adjust accordingly is a major part of the professionalism that the training builds up through the main course.
“The tool tells you all the time whether it is doing well — you just have to learn to listen to the chips.”