For a blowing-fan to be used with a small forge the base may be of '-in. deal to the shape and dimensions shown by Fig. 1. The two deal sides (Fig. 2) form a gradually increasing space for the air inside the fan. The vanes at A almost touch the tin covering, but from that point the space gradually increases until B is reached, where it is 4 in. wide. Screw the sides to the base at its narrowest part with a distance of 3i in. between them. Each side has two circular holes I in. to 5 in. in diameter; across these, pieces of sheet-iron 3/4in. by tin. are screwed, each iron having a hole in the centre to take a bushing of brass tube in which the spindle runs. A disc of wood 2 in. in diameter has a central hole bored to fit the spindle, and four 1/2-in. holes are drilled at equal distances on the periphery of the disc. Four pieces of wood, 3/4 in. square and about 4in. long,are tapered on the ends to fit these holes; each carries a vane of stout tin about 3i in. square. The fan can now be mounted on the spindle, the vanes being trimmed to fit as close as possible to the sides of the case without touching. To prevent side-shake,solder two brass collars on the spindle.

Enclose the fan by tacking a sheet of tin 4 1/2 in. wide completely round the case from C to E (Fig. 2), and make a tin nozzle tapering to about l 1/2 in. square and attach it at C. Now make a bracket D, about 9 in. high, on which to mount an iron pulley about 15 in. in diameter; by this a belt drives a pulley 1 in. in diameter placed on the end of the fan spindle. The fan should now be painted and finished.

Fig. 1.

Fig. 2. A Small Blowing-fan for a Forge.