Quainton Windmill

Quainton Windmill is a six-storey brick tower mill, 23.01 metres tall to the top of the cap, constructed in fair-faced red brick with vitreous headers. The mill tapers from an internal diameter of 7.08 metres at the base to 3.88 metres at the curb beneath the cap. An Ordnance Survey benchmark at 357 feet 6 inches is cut into the brickwork on the eastern side.

The mill has a white painted hemispherical bolted steel cap with a white painted fibreglass skirt, mounted on a timber head frame that projects to the rear to support an eight-vaned fantail on a braced timber fan stage. The cap revolves on sixteen cast-iron tapered rollers within an iron track mounted on the timber curb, held down by gravity. Four double-sided shuttered patent sails are mounted on an iron Lincolnshire Cross. Each sail is 9.14 metres long, weighs 914 kilograms, and has seven bays equipped with twenty-one shades on either side of a central timber sail whip. The sail driving and following edges are of galvanised steel, and the shades (sail shutters) are framed in galvanised steel and covered with glass fibre sheets fixed with stainless steel pop-rivets. All shades can be opened or closed simultaneously by the striking rules, a system of rods connected to a linkage at the centre of the cross called the spider, which is operated by the striking rod passing through the centre of the windshaft. The fantail rotor vanes are of fibreglass.

The ground floor and first floor both have timber stable-type doors with cast-iron fanlights to the north and south. Above the ground floor, the cast-iron windows were renewed during the 1970s to match the appearance of the originals, though they are slightly under-sized and are set in simple timber frames with segmental brick arches over. Each storey except the sixth (Dust Floor) is lit by at least one window. A timber door for lowering sacks of flour is situated on the east side of the second floor (Meal Floor) and was probably operated by slinging a block and tackle to the underside of the reefing stage overhead. The slatted timber reefing stage is supported on timber beams cemented into the wall and is accessed by timber doors from the north and south sides of the third floor (Spout Floor). The reefing stage was originally also supported by struts and is protected by a single round-section wrought-iron handrail made of segmental cranked lengths linked together by end hooks carried on timber posts.

All interior rooms are circular in plan with whitewashed walls and reduce in diameter as the tower rises. All except the sixth floor are illuminated by cast-iron windows; the Dust Floor is currently illuminated by diffused light passing through the fibreglass skirt. Each of the six timber floors is carried on a pair of heavy timber beams.

The ground floor was used as a store and is entered by a timber stable door beneath an original cast-iron fanlight in the southern aspect, with a similar door positioned directly opposite in the northern aspect. The floor is of glazed bricks made in 1978 and laid on the original dirt floor. A stone bed for a vertical steam engine is situated in front of the north door. The sack hoist control rope hangs down on the eastern side of the door and rises to the sixth floor (Dust Floor) to operate a clutch that engages the sack hoist drum and rope passing through the double trap doors in every floor up to the fifth floor (Bin Floor). A modern timber stair in lieu of a ladder rises to the first floor over the north door.

The first floor, now used as a workshop, is believed to have been a storeroom originally. The window over the stairs has been reduced in size and a two-light timber casement window has been inserted. A timber pulley and bracket is attached to the underside of the second floor (Meal Floor) above the window; this was for the control linkage from the third floor (Spout Floor) to the steam engine below. A timber ladder rises to the second floor (Meal Floor) against the southern side of the room.

The second floor (Meal Floor) was used for grading the flour and storing flour sacks ready for despatch. A door on the eastern side was used for lowering sacks of flour to carts waiting below. A belt-driven iron lay shaft for powering the wire machine, for dressing or grading the flour, is suspended from the ceiling and is connected by a belt to a further lay shaft that is meshed to the great spur wheel above the third floor (Spout Floor). The wire machine is contained within a timber cabinet suspended from the ceiling and the graded flour is collected in sacks hung below the machine. A timber ladder rises to the third floor (Spout Floor) against the west wall.

The third floor (Spout Floor) is the room from which most of the machinery was controlled. Overhead a timber T-frame beam supports the great spur wheel driven by the vertical drive shaft. A secondary drive wheel is attached to the base of the great spur wheel and can be meshed to drive a lay shaft for operating the wire machine on the floor below. The pair of millstones on the fourth floor (Stone Floor) above can be driven off the great spur wheel by meshing the cast-iron stone nut. Originally, two further stone nuts were used to drive an additional two pairs of millstones but these have been removed. Tentering gear for two pairs of stones is still attached to the underside of the T-frame. The butterfly handle and the tentering gear for engaging and setting the gap of the remaining pair of stones, a further tentering gear for the lay shaft, and a governor for controlling the riding up of the millstone at speed are also attached to the T-frame. The great spur wheel and the secondary drive wheel have timber teeth, to avoid the risk of metal on metal causing a spark that could ignite any flour dust suspended in the air. The crook string that adjusts the front of the shoe, to control the rate at which grain is fed into the millstones, is looped over a wrought-iron twist peg attached to the wall. A timber hopper fed by a flour chute or spout from the millstones above is situated against the wall on the north-eastern side of the room; this hopper in turn feeds the wire machine on the floor below. Doors on the northern and southern sides of the room allow access out onto the timber reefing stage, from where the striking chain can be used to adjust the striking gear that operates the angle of the shades on the sails. The brake rope also hangs down onto the reefing stage. The rope is used to operate a steel band around the brakewheel in the cap, that prevents the sails from turning. A timber ladder rises from the third floor (Spout Floor) to the fourth floor (Stone Floor) above the south door.

The fourth floor (Stone Floor) is currently occupied by a single pair of millstones housed in a timber case or tun, which has a timber horse or frame sitting on top of the case supporting a hopper and shoe that feeds the grain from the grain bins on the floor above. There is space for a further two pairs of millstones. A wrought-iron stone crane (installed in 2006) is adjacent to the case and is used to raise and turn over the millstones. A timber ladder rises to the fifth floor (Bin Floor) against the eastern side of the room.

The fifth floor (Bin Floor) has a pair of timber grain bins with lifting lids against the northern side of the room. A further single grain bin was once situated against the southern side but is no longer extant. The sack hoist trap door on this floor is raised up to waist level in order that the sacks of grain could be emptied into the bins with ease. Eight recesses with depressed segmental brick arches are situated in the walls; each contains the end of a holding-down bolt with a tensioning nut that is used to hold down the timber curb on top of the tower.

The sixth floor (Dust Floor) and the interior of the cap are accessed by a wooden ladder from the fifth floor (Bin Floor) through a hatch in the timber floor. There are no windows illuminating the interior of the cap but diffuse light does pass through the fibreglass skirt. The Dust Floor differs from the other floors as a large proportion of its area is hinged, to allow access to the cap and the machinery contained within it. A timber sack hoist mechanism situated on the northern side of the floor comprises a rope drum on a frame linked to a clutch wheel by a leather belt tensioned by the sack hoist control rope, driven by a pair of meshed cog wheels off the vertical drive shaft.

The cap and the machinery within it are mounted on a timber head frame, all of which revolves on the cast-iron rollers. The windshaft that rotates with the sails passes through the bolted steel cap in the neck bearing. The windshaft passes through the large canted cast-iron brakewheel that has pearwood teeth that mesh with a smaller horizontal wallower wheel, which in turn transfers the rotation of the sails to the vertical drive shaft that passes down the centre of the mill to the great spur wheel. The shaft of the luffing gear, which is driven by the fantail, enters the cap on the opposite side from the windshaft. It has a worm at one end that meshes with a pinion onto a cast-iron rack attached to the inside face of the timber curb. As the pinion is rotated, it meshes with the toothed rack and moves the head frame, thus keeping the sails facing into the wind.