I have tested it on steel and stainless steel (but not now on a steel beam). It's frightening how well the cutting bit works its way through the material. We must not build up too much pressure because the Dremel himself then in his hand is just restless. I guess that's because of the hardness of the material that can not be milled off too quickly. But I can by milling a steel rod without problems. The metal pieces but you have to be very careful. Mouthguard and eye protection are recommended.
