Mill Repairs 2015 - Day 5
– 4th July 2015. Mostert’s Mill Tackling the Stones
The brake wheel and lantern pinion mesh well now, so after one or two Milling Days to keep up interest from the Public and to generate some funds, we knew that the second part of the job was in store still, the dressing of the stones. There was no wind forecast for today so it seemed an ideal opportunity to tackle the job!
Road sign next to Mostert’s Mill
Our tool list included my ‘staff’ which I had to ‘prove’ on the big Mitchell lathe bed first. I haven’t used it for a long time and I wasn’t at all surprised to find it had developed a bow. It touched at both ends and there was perhaps a millimetre gap in the middle. After some belt sanding, then hand sanding the high spots off, I had decent contact area between the chalked lathe bed and the staff.
Proving my staff on the flat bed of the lathe
Neville had opened up and was waiting for me. He with a car full of tools to go along with mine and Paul’s; we were well equipped, but one never has everything! We soon had the furniture stripped off the stones, although to remove the long beams of the horse, the corners of the upright shaft need to be turned out of the way, so the brake had to come off and the diagonal ‘preventers’ removed from between the brake-wheel rim and the sprattle beam. We had to turn the wind shaft anyway, so that one of the flat surfaces faced down, to give maximum clearance to lift the upright shaft out of the eye of the runner stone. We also lifted the two halves of the floor and tied them safely to prevent them falling closed when least expected!
For lifting, we had a chain block hanging from a strop on the wind shaft, first on the brake wheel side of the tie-bars, then we realised we wouldn’t be able to pull the shaft away from the sprattle beam like that, so we hung it on the other side.
Strop hung on the brake wheel side of the tie bolts
Looking down, the strop is now on the other side of the tie bolts, the chain block on it is connected to the other strop around the upright shaft. Neville is loosening the bolts on the pintle bearing
Then the other strop was wound twice around the upright shaft, with a safety rope down to the quant at the bottom, in case it slipped upwards. Neville is removing the nuts and wedges on the pintle bearing housing in the picture above. The strop is now on the other side of the tie bolts. With the chain block in this position, the fork on the quant lifted cleanly off the rynd without any tilting action, which has been a concern before. There is still not enough clearance when the pintle up against the wind shaft, but by swinging the lantern pinion to the left (opposite side to the brake lever), it was easy to lift further, making sure the lantern did not hook up under the sprattle beam. The quant could then clear the eye of the runner. Once out, we had a wooden block on the floor ready for it to rest on, at the top of the stairs so that we could lower the fork of the quant on to it and tie the upright shaft safely into that corner of the opening.
I had brought the chain-and-rod cradle which we use to lift the runner at Compagnes Drift. It was just big enough for this stone. Here the 16mm rods are laid out on top of the runner:
Cradle laid out on top of the runner
It’s only necessary to raise the runner with the tentering mechanism by a little more than 16mm to assemble the rods. Shackles on the ends of the four chains of the sling go over the ends of the two long rods, right against the edge of the stones, then the shackles welded to the ends of the shorter rods are slid over the ends. They just hold the long ones apart. We used rags under the chains where they passed over the top edge of the runner.
Chains connected to the ends of the rods
Lifting, with rags under the chains to prevent damage to the top edge of the runner
The next problem was to disengage the tapered cock-head of the stone spindle from the rynd. For this I had brought a heavy duty automotive puller. We cut two short lengths of ready-bolt and assembled the two halves of the bearing puller under the rynd and connected the legs of the threaded part to it. With a bit of adjustment we had a fair amount of force downwards on the stone spindle and upwards against the rynd. To prevent the stone spindle falling and damaging the hollow curved end where it runs on a cannon-ball, Paul raised the bridge tree to just touch. The stones were still just 16mm apart with the runner resting on the bars of the cradle. A couple of fairly strong belts on the top end of the puller with a 4-lb hammer while under tension, was enough to just dislodge the tapers, the stone spindle just dropping away a couple of millimetres.
Puller assembled under the rynd to force the stone spindle out of the taper
We could then lift the runner on its own. Working ever safely, as it lifted, blocks of wood and the ‘many-heights’ were used between the stones in case anything went wrong with our lifting apparatus. Our next plan was to hang the runner from a hollow dummy cock-head I had made, to check its static balance. I had used a 3mm wire rope through the hole in the middle with two Crosby Clamps inside the hollow end and with a loop at the top end with two more. Still with the blocks under the runner, we tried lifting it.
The wire rope snapped where it passed through the top plate of the dummy. Was it from the sharp edge of the hole underneath? Maybe. We changed the arrangement by drilling a bigger hole so the wire could pass twice through it and assembled with the wire around the bar of a D-shackle and out through the hole again with the Crosby Clamps above the dummy and tried again. The wire snapped again. Clearly not strong enough! We dispatched John to Hawkes and Findlay in Observatory where he found some 7mm wire and suitable clamps for that size. He also came back with a super book on Observatory and all its old buildings and Windmills!
However, we had moved on, by arrangement. We can do the balancing later. We turned the runner over using the strop through the eye of the runner passing one end through the other to pull tight. We had the ‘work table’ in place. This is very sturdy and the same height as the top surface of the bed stone.
Lifting one side of the runner to tip it over
Using wooden blocks under the edge, we gradually lifted one side up, gave it a nudge at the balance point and lowered it on to the table. We used a towel on the chain as we lowered to keep the chain wawy from the beam on that side. Alan is making sure the runner didn’t slip inwards with his foot. Later he used a wooden spacer there between the runner and the stone spindle.
Lowering the runner upside down on to the table
Fortune did a great job of cleaning the bed stone. It’s well known that these stones were not a pair, the runner being dressed with harps and the bed with sickles. This is the first time I’ve seen sickle dressing in the flesh and I wasn’t surprised to find every second sickle only reaches half-way.
Sickle dressing, up close
Our next job was to check if the bed stone was level. As expected, it isn’t. There is about 3 to 5mm to lift on one side.
Checking for level, with the spirit level on the staff
We thought of several methods of lifting it, but we didn’t have the right tools. The bed stone is firmly wedged into a solid heavy curb which will probably have to be lifted along with the stone and either left like that or ‘encouraged’ to go back down into its place on the floor once the stone is level. The curb is fixed down with bolts which pass right through the hurstings, not with nuts on the end, but wedges. The wedges have a tail on the wide end through which a nail was driven upwards into the hurst frame. Luckily these broke away easily and it was possible to drive the wedges out and save the washers. These are now attached with fine wire to the slots to make sure they don’t get lost or mixed up!
Curb retaining bolt wedges and washers are tied in place
So the next job was to take a tracing of the harps, off the upturned runner. We did this first with brown paper, then transferred it to a piece of hardboard which I got on Friday from Simon of Overberg Joinery Works, who replaced the rotten longbrace beam some time ago.
Simon repairing the longbrace a few years ago
Tracing the harps off the runner
I then laid the paper over the hardboard and used a knife to transfer the pattern.
Transferring the tracing to the hardboard
I then used a handy electric tool called a Renovator to cut through the board to work as a stencil.
Stencil over the bed stone, registered on the stone spindle
We measured the diameter, calculated the circumference, divided that by eight for the harps and made eight equally-spaced marks on the iron band around the bed stone. By this time we were pretty tired and had difficulty working out which way the harps should face to match those of the runner, so that the crossing angle would encourage the partly milled grain outwards. I had brought along (to show it off!) Nigel Harris’ new book, Watermills and Stoneground Flour Milling. He came to the rescue on page 118, with pictures of a pair of stones from Letheringsett. The runner in that case turns in the opposite direction to ‘ours’, but it can be clearly seen that when the runner is upturned, the pattern of the harps on one is in the same direction as the other. So the stencil is used the same way up on each!
Even though much must still be done to the upper surface of the bed stone to get it level and flat, we decided to mark out the harps using a thin diamond impregnated disc. We marked a ring at a suitable radius on the disc so as not to cut too deep nor be too shallow and off we went, each time using our marks on the iron band against the stencil to make sure we were exactly one eighth of a circle away from the last.
Using the stencil to cut grooves in the bed stone to a certain depth
The result was very pleasing!
Harps marked out on the bed stone
We have arranged to meet again in four weeks for another work party. For that, we will bring suitable apparatus to raise the bed stone. We will use offcut hardboard as shims. I will reassemble the dummy cock-head with the thicker wire rope.