Securing the Sails

THE WINDSHAFT

The windshaft is simply the steel rod attaching to the centre of the sails, and this has to be strong and very firmly secured, to cope with the weight of the sails, normal rotation, and with any unusually strong winds.

The steel rod purchased was actually a bolt, 20cm. long with a  12mm. diameter. One end was hexagonal for holding/turning with a spanner and at the other end  was a screw thread cut into the 12mm. diameter. (It was important that the screw thread diameter was no bigger than the diameter of the bolt - as can be the case with dome-headed coach bolts)

Dealing first with securing the windshaft to the capping base the easiest answer, for a model, would have been to make the windshaft fixed (at a suitable angle for the sails to clear the tower) and for the sails to revolve on the end of the windshaft/steel rod.

In my enthusiasm however, I hoped to have the sails actually doing work (driving a cycle dynamo to generate a visible light on top of the mill) and this meant that the sails would have to be fixed to the windshaft, which would then turn a dynamo located within the body of the windmill. (This was the reason for the 'square holes', as I felt that there would be insufficient room to fit the mechanism within the capping area.) 

It followed that the windshaft must be able to turn with minimum friction in its seating, and the 'construction' shown below was my solution to the problem. 

COMPONENTS:

Two blocks of wood, each 4¹/₂" long and 1⁷/₈" wide. 1⁷/₈" deep at one end and ⁷/₈" deep at the other.

Two nuts (which fitted the 'hex' bolt used as the windshaft), but with the internal screw threads filed flat, so that they would slide over the screw threads on the bolt  and minimize friction when the bolt revolved.

Two nuts to stop bolt sliding out of housing.

Side pieces of ¹/₄" ply.  2 x  4¹/₂" x 3¹/₂"

Wood strips for packing.

PLEASE NOTE:

1. Slope on top block to fit capping cover.
2. Metal plate at rear of top block adding strength to support for rear filed nut.
3. Strips at each side acting as rain gullies.

4. The three 'drawing pins' seen on the front at the top were just right to maintain correct shape of capping cover, which had a tendency to warp at that point.

FRONT

BACK

The two filed nuts were positioned on the centre line of one of the angled blocks (each nut standing on one of their faces) ¹/₄" from the front - high end, and ³/₈" from the rear - low end.

Small nuts/washers were then laid down, and  fastened in front of, and behind each filed nut,  to prevent forward/backward motion.

The other angled block was then carefully pressed on to the top of the filed nuts to mark their positions, - quite tricky -  and once again small nuts/washers screwed to the block to hold the top of each filed nut securely. Fastening the two blocks together would now prevent any forward/backward motion of the two filed nuts.

Strips of wood were then fitted at each side of the nuts with extra packing where appropriate, so that screwing the the side panels tightly, would ensure maximum compression to prevent sideways movement, while at the same time, holding upper and lower blocks firmly together.

When completed, this whole contraption was attached to the capping base with three screws coming up from underneath, plus a bracket at each side for luck. - Yes, this meant temporarily removing the turntable previously attached.

A block of wood 2" x 3" x 4" was drilled exactly centrally and vertically through the 4"x 3"face, to the diameter of the bolt, which was then pushed through, in order that the hexagonal end could be marked roughly.

The drilled hole inside the  marked area was then enlarged at that end; but so that the hexagonal end of the bolt would fit firmly, the enlargement was less than the marked area, and the 'hex' end fitted flush by gentle application of a hammer.

Plastic wood filled gaps at the hex end (there should'nt really have been any gaps) and the sails attached with two substantial screws through the 'top' sail, (the sail which overlaps the other at the centre) into the block. Two brackets were then screwed from the other sail to the sides of the block.