Monday, 13 May 2013

More grist to the mill


Stretton Watermill
(click on any picture for a larger image)

Last weekend was ' National Mills Weekend' and Stretton Watermill south east of Chester celebrated it with 'Enthsiast Days' on Saturday, Sunday, and Monday. On the last two days, guest millwright Malcolm Cooper was present. I was occupied with Nimrod and Concorde tours at the Runway Viewing Park all day yesterday, so went to Stretton today to meet the millwright to pick up some knowledge about dressing mill stones, and anything else Malcolm could impart. My mate, also named Malc, came with me.

The mill building showing the external overshot waterwheel. There is another such wheel in the opposite end of the building.

The mill pond is formed by the dam, which also acts as the back wall to the mill building

Mill guide Kate Harland explains the operation of the Pit Wheel (the gear attached to the water wheel axle) and the Wallower (the gear that meshes with the Pit Wheel). The large gear at the top of the picture is known as the Great Spur Wheel; it transfers the drive to the mill stones via the small pinions on the Runner Stone drive shafts (the upper, rotating one of the two mill stones in each grinding set). These small pinions are known as Stone Nuts. The frame that contains this mechanism is the Hurst frame; ours at Nether Alderley is relatively new and made of cast iron, whereas this one above is wooden.

The other water wheel at Stretton; this one is inside the mill building and was replaced in the 1800s, so uses cast iron in its construction

One of two sets of stones (inside their wooden encasement, or 'furniture') with a 'horse' frame on top supporting the grain hopper. The stones are driven by the internal water wheel. There are two more sets driven by the external water wheel, though these are not in use at present.

A  mill stone, showing the pattern of cutting grooves in the surface. The stones are used in pairs, the bottom or 'Bed Stone' does not rotate, while the upper or 'Runner Stone' does. The grain is fed into the centre of the Runner Stone and works its way to the edge, getting ground steadily finer as it goes. The surface of the stone is concave, being about 1/4 of an inch lower near the centre than at the edge. This forms a 'reservoir' for the grain to be poured into and 'dressing' the stones (a skilled job done by the Millwright) is mainly concerned with cutting out this 'reservoir', which gets shallower as the stones wear. The outer section of the stones generally wears to match the other stone of the pair and the Millwright will not wish to lose this ideal 'interface', but will perhaps deepen and sharpen the edges of cutting grooves in the stones .

Kate demonstrates the Sifter, which separates the white flour from the courser components of the the output from the mill stones

Two Malcolms! Millwright Malcolm Cooper explains the finer points of the mill's gears
to my mate Malc.

Malc and Malcolm discuss the dressing of mill stones. The length of wood that Malcolm is holding is used to find 'high points' on the stone's surface.

Here's a video of one of the sets of stones in action. The grain is fed in down the 'shoe' which is agitated by the 'damsel' (a 4-sided 'cam' device).
Mill stones working

This video shows the sack hoist in operation. This lifts the sacks of grain to the top of the mill where they can be loaded into the grinding hoppers.
Sack lift in operation

It has been a most informative day out, and enjoyable, too. Thanks to Kate of Cheshire West Council (who run the mill) and to millwright Malcolm Cooper for imparting their knowledge. I know I'll find that useful in my work as a volunteer at our local Nether Alderley Mill (see 16th March 2013 entry on this Blog).

Today was one of cumulus cloud build ups and isolated but heavy showers, so we had left the bikes at home and driven to Stretton in my MX5. We had the top down in lovely sunshine for the outward journey, especially lovely as we went the pretty way through Peover, Lach Dennis, Whitegate, and over the Peckforton hills to Broxton and Stretton. By the time we were coming home, however, the heat of the sun had kicked off the showers and we kept the roof up.



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