This is a facing lathe by Death & Elwood which was used to bore holes in wheels and turntables.

Everything is about slate in this museum which is right next to Llanberis at the shores of Llyn Padarn. From there whole mountain sides have been "converted" to slate in all shapes and sizes. But because you were in North Wales they had to do everything "in house". So there was a huge water wheel which provided power via the shaft at the rear throughout all those toolsheds where they had a foundry for the smaller parts and tools, a proper big foundry for waggon wheels and all kind of slate cutting and finishing equipment.