Tuesday 14 September 2010

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!