A loose dress.
One careless move and that lathe will have her all tangled up in all sorts of ways. In fact, she'd be wise to dress in Jeans or attractive slacks, and a blouse that's neatly tucked in at the waist. She would also be wise to make sure she is buttoned up and that there are no loose ends anywhere. Lathes look harmless, they are just like any other machine; care must be taken when working on them.
The only worse thing she could do would be to be careless around a band saw or a table saw.