Which blade should I choose? Thin blades will always cut quicker. On thin steels a thin cutting disc will give the fastest cut and a cleaner edge. Thicker blades will always last longer, but... On thicker steels a thin cutting disc can become unstable if too much pressure is applied, the disc may warp in action and become more vulnerable to breakage. We would always recommend a thicker blade when the steel is thicker than 2mm.