Restoration of No 1 stone

Acorn Bank watermill has 4 pairs of stones. Nos 1 and 2 are respectively an oat shelling stone and a French burr, driven by the upstream waterwheel. The downstream waterwheel is incomplete, so any work on stones 3 and 4 will be part of a much larger project.

We decided to begin by restoring stone no 1 to rotation, with no intention of shelling any oats, simply because it looked easiest! This is a diary of the restoration, interrupted several times by the need to repair other parts.

No 1 stone before restoration

09/06/2009 Fitted supporting beams and used hoist to lift no 1 shelling stone. Stone wedged back against wall.

The bed stone and rynd...

...and the runner (photos courtesy Martin Watts)

15/06/2009 Dismantled bearing in no 1 bedstone. Bearing in good condition; to be recorded before reassembly. Checked engagement of stone nuts - they will not lower far enough to engage spur wheel.

11/08/2009 Checked alignment of no 1 stone driveshaft

18/08/2009 Removed stone driveshaft and stone nut. Adjusted position of drive taper (25mm down). Left machine secure for weekend

25/08/2009 Removed tentering beam and treated with timber preservative, cleaned and painted shaft. Removed beam socket box and painted with primer. Refixed in wall socket.

01/09/2009 Reassemble tentering beam. Make lead bearing cover for same. Measure stone separation etc to ensure proper engagement of stone nuts with spur wheel. Removed part of tun base and floor boards to investigate possibility of moving bedstone to correct gear meshing.

08/09/2009 Cutting beams and floorboards so bedstone can be moved. Clean stone drive shaft.

15/09/2009 Levelling floor round no 1 stone and removing tun base

06/10/2009 Moved no 1 bedstone 10mm further from main shaft and levelled.

13/10/2009 Replaced stone drive shaft. Stone nut assembled to shaft in pit and whole assembly hoisted in several stages by rope through bedstone bearing. Bottom bearing and bearing block added afterwards. Bearing rebuilt by inserting sacking impregnated with oil, and re-attaching the 3 wooden bearing surfaces. Rynd attached. Stone nut lifting fork reattached - some difficulty separating stone from taper. Wheel run to check assembly - good! Stone nut tried in different orientations, but still does not run level.

23/03/2010 Fit wooden octagonal bezel to no 1 bedstone.

14/09/2010 Refitted no 1 stone. Packing pieces made from sheet lead, thinned at edges so they could be hammered in. Rynd tried in position and depths measured to estimate thickness of shims required. Stone approximately levelled - running true to drive shaft, but could have moved bed stone a few mm further out as shaft is at slight angle, so stone higher at upstream side. This is corrected over next few weeks by repeated small adjustments of bottom bearing as gear teeth wear in. Whole machine runs quieter with stone turning.

The first time a stone has turned for at least 60 years!

Preparing to restore the French Burr stones

The second pair of stones in the mill are French Burrs, which were used to mill wheat flour. Like the first pair, these stones have not operated since WWII.

Naturally, we would like to restore these stones to working order with the intention of milling some flour in due course.

There are several problems - we have no idea what state the stone faces or bearings are in, the support beam is twisted, the stone nut is mounted too high on the shaft to mesh with the spur wheel, and it is also too close to the spur wheel so the gears cannot engage. Apart from that and the fact they are enormously heavy (over a ton each), it looks quite simple. Oh, and there is no beam in the roof in a suitable position to attach a lifting block.

So, the first step is to fit a lifting beam. After lots of calculations to work out how big a beam we needed to span the 3m gap between roof timbers above stones 2 and 3, we eventually ordered a length of oak, 3.5m long and 20cm square. On August 10th this 150kg monster was dragged across the yard on rollers and then pulled in through the half-door by a hoist attached to existing timbers. By using hoists in various positions, and extra manpower provided by Chris Braithwaite, we eventually got it lifted into place.

The lifting beam in position with 3 ton chain block

07/09/2010 We fitted blocks to the ends of the beam to stop it slipping out. During the hammering a bat fell out of the roof. Following instructions, we picked it up (wearing gloves) and stuck it on the wall, from where it flew back to safety.

Repairing the Sluice

13/04/2010 Sluice gate has collapsed under water pressure due to rot.

The new sluice gate

At first we inserted plywood boards to reduce water flow.
Removed side posts (grooved for sluice gate boards), which were cemented into channels cut in stonework. Make new boards and design and manufacture new sluice valve with steel blade and slides and screw control. Install new sluice mechanism. Replace rotting bridging boards with more stable arrangement.

01/06/2010 Make new weir handrail from scaffolding sections.
08/06/2010 Weir handrail fitted - adjusting the sluice was previously a hazardous activity.
15/06/2010 Finishing fixing of weir handrail.
22/06/2010 Further work on weir handrail.
28/09/2010 Wheel control added.