Found this report in "Gwynedd Slate Quarries - An Archaeological Survey 1994-95. Report No.154 :-
Sawing machinery rarely survives in abandoned mills. Australia mill at Dinorwic is unique in that its thirty-six Ingersoll Rand saw tables remain in situ, mostly in very good condition, still with lineshafting and the vacuum extractor systems. A large double saw-table and a planer survive in the ruins of the Bonc yr Offis at Pen yr Orsedd, which accordingly appears in the list despite the low survival of the building itself. Broken sand-saw blades were observed at Pompren near Dolwyddelan but insufficient remained to indicate bow the saws were powered or functioned. Otherwise little remains in any site visited.
Evidence for the type of saws used in a particular quarry was sought in the sawn-end offcuts on tips, and in rubble used for building quarry structures. In most cases the saw used was a standard circular pattern, probably the Greaves patent, which involved a slotted table moving against the blade. Offcuts
from sand-saws (horizontal saws, in which blades are tensioned in u carriage suspended from a frame and then moved backwards and forwards across the block), with their distinctive smooth lay and ridge where the cut was snapped, were observed at a number or quarries in Dyffryn Conwy and its tributary valleys, particularly Cwm Eigiau (20100) and Cedryn (20106), and it is known from archival sources
that sand-saws, once general throughout the county, remained in use far longer here, because they could cope with large slabs and deal better with pyritic rock than circular saws. The Hafodlas mills include the bases for such machines, but no substantial sand-saw remains were observed in any of the sites visited. The Hafodlas mills also provide the best evidence for the use of the Hunter patent saw, with their distinctive machine bases.