This toy is worked by a small stream of sand trickling from a hopper on to a wheel shaped like a miniature watcrwheel and compelling the wheel to turn by its weight.
The general principles and arrangement of the mill will be gathered from Figs. 1 and 2.
The case used for the mill in this particular instance measures ll inches in height, 6 inches in width, and 5 inches in depth (inside measurements). A good height is necessary to give room for a large hopper above the wheel, without bringing the sails too near the bottom.
The case is fitted with a front G and back H, which are held in place by fillets F F running round the inside. Space must be left at the front for a sheet of glass to fit in flush.
When these two parts have been made, holes should be bored in them for the wheel spindle, which may be part of a knitting needle. Pieces of tin, suitably pierced, are tacked over the holes to act as bearings and keep the spindle out of actual contact with the wood and give easy running.
– Back view of Sand Windmill with back removed, showing sandbox and wheel. The broken circle Indicates the path taken by the tips of the windmill vanes.
The sandbox had better be made separately and screwed to the front before this is fixed in place. It will be seen that c is considerably shorter than B, to allow the hopper to be refilled by rotating the case.
The wheel is H incnes in diameter. A cotton-reel, 1 inch thick at the middle, with its ends sawn off, forms the boss. Mark out two Li-inch circles on a piece of very thin wood, and from the samo centres describe circles just larger than the boss.
The lines on one drawing must slope in the opposite direction from that of the lines in the other, and must have the same slope.
– Side view of Sand Windmill, for explanation see text.
Having drawn in the lines firmly, prick holes through the centres to show on the other side, cut round the large circles, and glue the pieces to the ends of the reel, the marked faces inside. The small circles will make centering easy. Be careful to get the two sets of lines squarely opposite each other. The spokes are slips of thin wood carefully glued so that their ends cover the lines joining the circles on the ends.
Using the pricked centre-marks as guides, bore holes to fit the spindle tightly, and when the wheel has been adjusted to come centrally under the sandbox, fix it to the spindle with liquid glue smeared in the angles.
The spindle is prevented moving endways by blocks EE being glued to it, and by beads or small washers interposed between these and the tin bearings already referred to.
The sails are tapering pieces of cardboard or thin wood, glued on the front of the arms of a cross fret-sawed out of jfo inch plywood. The arms should be bevelled slightly, to give the sails a slope, and bring their leading edges a trifle nearer the glass than the rear edges. The face of the front should be decorated, if possible, with a picture of a windmill, centred round the spindle, with a background of clouds and open landscape.
The sand used for working the windmill is silver sand (obtainable at any oil-shop), riddled through a sieve of very fine mesh. Such a sieve may perhaps be found in the kitchen. Sieving is very important, since a few large grains or bits of rubbish might easily block the hole and make it necessary to take the back off to clear it. Before being sieved the sand should be thoroughly dried.
The size of the hole in the bottom of the hopper should be between A and ½ inch across. A circular hole is preferable to a narrow slot, as being less likely to cause jamming.
The joints behind the front should be made sandtight by pasting strips of paper in the angles. The case should be covered with stout paper or binding cloth, the edges of which are turned over and pasted down neatly on to the glass and back.
To recharge the hopper, turn the case round slowly, to allow the sand to run down the side and collect at the mouth of the hopper, which it is made to enter by another part-turn.
Windmill, A Simple. The vanes are four pieces of stout sheet zinc, 8 inches long and 2 inches wide. One end of each is inserted into a saw-cut in a fac3 of a wooden block, li inches square and 2 inches long, and secured by a couple of
I – d „.y thin wire brads. After fixing, the vanee are twisted, all in the same direction, till their tips, as viewed endways, lie at an angle of about 60° to their fixed ends.
The shaft is a piece of galvanized wire, about ½ inch thick, sharpened at one end to stick into the hub, and given a right-angle bend at the other. It turns in two httle brackets of sheet brass, nailed to the top of a 10-inch length of 2-inoh by J-inch wood, slit at one end to take a tail, also made of sheet zinc.
A hole has to be bored in the body for the nail – projecting from the top of a pole – on which the windmill will swing to face the wind. The correct position for the hole will be found by resting the be replaced by a disc 12 inches across, body on a sharp edge and moving it about slit by radial lines to make a large number until it balances. Make the hole at the of vanes li inclies wide at the tip. These balancing-point, are all given a twist in the same direction.
Side view of an easily made model Windmill.
Large beads are interposed between The disc may either be soldered on to the vane-hub and bracket, and between the end of the spindle – which is the the body and post, to make movements neater method – or be tacked to the easier. Face of a wooden hub, as in the other The separate vanes may, if preferred, case.