Fron Factory, also known as 'March Melin' (mill of the stallion), was a water-powered woollen mill, operational until around 1840. It lies in a wooded valley on the northeast bank of the Nant Gwynllyn, about 1km west of Rhayader. Now a ruin, the two-storey building measures internally 8.95m (29 ft 4in) east to west by 6.83m (22ft 5in) and stands in the eastern corner to about 5m (16ft) high. The walls are constructed with very thin small stones with substantial undressed quoins to the corners. The waterwheel was at the western end, where a cast iron gear wheel protrudes from the ground inside the building: the rim of the wheel is 140mm (5 1/2in) wide and 57mm (2 1/4in) deep; slots for wooden gear teeth are 90mm (3 1/2in) wide by 30mm (1 1/8in) and at 62.5mm (2 1/2in) pitch. Excavation in the 1970s revealed that the wheel, mounted directly on the waterwheel axle, was about 2.3 metres (7ft 6in) in diameter and that its wooden teeth meshed with a smaller gear wheel on an iron axle upon which were three wheels. Around the wheels were bolted timber strakes forming a drum, which would have driven the machinery from below by means of more than one set of belting. The drum drive and the fine stones used in the wall construction indicate that it is unlikely the building was a fulling mill, as has been suggested. There is no visible evidence of a mill pond, the leat approaching the mill from the northwest as a slightly sunken terrace; field inspection suggests an (overshot) waterwheel diameter of about 4.3 metres (14 feet).
Two cottages (nprn 420599) lie immediately adjacent to the mill on the southeast.

Sources: G. Tucker, Watermills of Radnorshire, in Melin, the Journal of the Welsh Mills Group, vol. 5 (1989), p.43 and plate 15;
G.W. Ridyard, Supplementary notes on the water mills of Radnorshire - part IV, in Melin, the Journal of the Welsh Mills Society, vol. 13 (1997), pp.83-86 and plates 13 & 14; Field visit B.A.Malaws & W.J Crompton 09 November 2014.

B.A.Malaws, RCAHMW, 11 November 2014.