When the tower rebuild was finally completed we knew the next task was to find and fit a curb. This was a job only a professional millwright could undertake and it was frustrating that despite asking our contacts for several months about the chances of getting hold of a second-hand one or failing that what the price for a new one would be we could never get a definite answer. Then, finally, a breakthrough occurred and the situation changed dramatically for the better. We were driving past Mount Pleasant Mill in Kirton Lindsey and we noticed it's cap had been removed and was sitting on blocks in the car park. On enquiry the owner told us that following 'back winding' the iron cross had snapped causing serious damage and that the repairs were being carried out by Adam Marriott from Teme Valley Heritage Engineers. Wasting no time we contacted Adam and he promised to come over and see our project as soon as he had some free time. A site visit eventually followed. After climbing the tower he commented favourably on the dimensional accuracy of the new
brickwork we had commissioned, declared the job feasible and promised to quote us for making and fitting a brand new tailor-made curb. To cut a long story short we accepted his quote and work started on the tower. First we removed the waterproof cover which allowed him access so he could take a pattern in plywood of the top the brickwork, marking the exact position of the built-in holes for the holding down bolts. Taking this back to his workshop he recreated the total circumference of the tower and divided it into eight identical segments thereby establishing their dimensions in plan view. After considering several options he chose the mechanical design he thought most suitable for the completed curb. This was passed to a patternmaker whose finished work can be seen in fig.1 painted red together with a nine toothed pinion in yellow to gear down the fan speed and provide sufficient power to drive the cap round. Adam’s extensive knowledge of metallurgy was employed in selecting a grade of cast iron which is far stronger than the original.
Artist’s Impression of the Mill after Restoration
This can be seen in fig.2 being poured into the mould at the foundry, Purbright & Co Providence Works, Willenhall. There were a few problems with the pours but eventually we had a full set of curb sections (fig.3) ready for fettling and transporting back to his works at Teme Valley. While casting was in progress Adam contacted his timber suppliers and made a selection of restoration grade oak. This was cut into a set of eight curved segments complete with mortise and tenon joints in each of their ends so they could be assembled into a complete circle to fit the brickwork top (fig.4). Lying on them is a section of the plywood pattern Adam had taken at the mill. Now, with all the parts to hand, he made a trial fitting in his yard where he checked the relevant fits and when satisfied all was good drove to the site in Filey
and assembled the complete curb unit. First the oak frames had to be joined using a rubber mallet to ‘persuade’ the mortise joints to align (fig.5). When satisfied the circle was true the joints were pegged with trenails (fig.6) and their excess length was trimmed off with a saw. The cast iron curb
sections were then man-handled onto the frame, slid into position, and fastened down securely (figs.7 & 8). We now had a fully operational curb sitting on straw bales waiting to be craned up the tower and bolted into position. We couldn’t thank Adam enough after our earlier frustrating experiences.
By now it was the end of October and our problem then was - when to book the hire of the crane? The parameters for the weather were a dry day with a wind speed of less than 10mph. We studied the medium-term forecast, chose a date with what should be acceptable weather and that also suited all the parties involved, crossing our fingers that the Met Office prediction would prove correct.The day arrived and conditions could hardly have been any better. First a working party removed the heavy plastic waterproof cover from the tower using a cherry-picker. By the
time they had finished the heavy crane had arrived on site. Adam liaising with the banksman and crane driver soon had the curb assembly lifted off the bales and raised above the mill (fig.9). Because of its weight positioning it needed to be precise in order for the holding-down bolts to align with the tubes built into the brickwork leading down to the oak pads. Adam had marked the timber frame with guides to ensure things all matched up as he stood aloft and steered the curb as it descended into the right position (fig.10).
The cargo straps used to lift the curb can be seen in fig.9 and to prevent them being trapped underneath the frame when it was lowered wooden spacers were placed on the bricks. They were then pulled out by levering the curb up to free them. Adam drove the 4’ long bolts down through the brickwork and tightened the nuts against the oak pads set in the top floor wall (fig.11) pulling it firmly down onto the tower top. The heavy duty waterproof cover we’d designed and had made from ‘curtain-sider’ material was fitted over the curb and frame and tied down securely to the tower ring bolts in the fast fading light. It was very satisfying for us to have finally made a start
on replacing the mechanism of the mill and for that we have to thank Adam for his invaluable diligence and expertise.
With the curb installed our collective attention now turned to the next major requirement for completing the project - the two largest individual castings: the windshaft and the iron cross. We emphasized from the start our plan was to restore the mill to its true original appearance. To make this possible Adam had been searching the windmill community trying to locate a second-hand Lincolnshire type windshaft rather than
the pole-end type used elsewhere but was finally forced to admit defeat. This meant a new one had to be cast and therefore a pattern would have to be produced for the foundry. The method adopted was to create a half-pattern as shown in fig.12 mounted on a back board; this would be used twice to produce two half-moulds which, when fastened together, would provide a full mould for the molten metal see fig.13.
readying both units for collection. The pictures hardly do justice to the size and weight of these two vital components; quality engineering produced in Yorkshire by H Downs & Son, Peacock Works, Huddersfield.
We now had brand new metal castings (figs.16 & 17) specially designed and made to fit into the new cap which Adam was constructing for the mill instead of making do with second-hand items. Needless to say there had been delays and hold-ups along the way, due in part to the lock-downs imposed because of Corona Virus, but Adam kept pushing the job along to the best of his considerable abilities. His next task was to arrange machining which was going to present problems. Workpieces of this size and weight take some manoeuvering and need a very special lathe (fig.18) to
accommodate them. The accuracy of the bearing surfaces is particularly important in the case of the windshaft to ensure the smooth running of the sails. Adam entrusted the work to HMS Engineering Ltd., Hereford who were also involved in devising the optimum method for keying the shaft to the cross. While all this was taking place the bronze head and tail bearings (figs.19 & 20) which will carry the weight of the windshaft and cross were being cast by a specialist foundry AJD Foundries Ltd., Dudley.
Now, with the castings well on the way to completion, we can catch up on the major woodworking taking place at Adam’s yard. He had been busy locating suitable pieces of oak (fig.21) to fashion into the weather beam, sheers and other components of the cap frame. With these items in stock large scale carpentry and joinery skills were employed to joint and assemble the main framework of the cap
base. Slowly the outlines became clear and finally in picture (fig.26) we see the cap frame and the gallows for the fantail all in position.
When we began our project to rebuild Muston windmill we had no illusions about the size and complexity of the task we were undertaking. The story of our struggle to first obtain planning permission and then organise the rebuilding of the tower is told in the preceding pages of this website; however we felt that those readers with a more specialised interest in windmills would find additional detail regarding various engineering aspects of the work valuable. In an effort to cater to their needs we have added a Technical Blog page to the site.
In photograph fig.27 we can see the last two large timbers being worked on. They are the spars or technically speaking the ‘spears’ that are mounted on the gallows and which support the fan. Fig.28 shows the four castings known as ‘pigs’ on which the cap frame is
mounted; they support the total weight of the cap, sails and fantail assembly while sliding round on the curb as it rotates. One of the important maintenance jobs essential to the mill’s smooth running will be to keep their load-bearing surfaces lubricated with thick grease.
To be continued…
Fig.29 above shows the spears being mounted to the gallows on the cap frame, their job is to support the weight of the fan assembly. To the right Fig.30 illustrates Adam’s progress in marking out the position of the bearing housing on the tail beam and now beginning to chop out the wood to insert it. The bearing itself is sitting next to his hammer and chisel on the beam. He recently collected the new fan hub casting from the foundry and has started making the spokes and blades to complete it. Photograph, fig.31, is of a recently completed fan destined for another customer but which looks very similar to how ours will appear when its assembled. The large size of these units can be judged by comparing it with the vehicles behind. Meanwhile we are organising suitable dates when we can get the team together to give the tower another two coats of tar before the long awaited day finally arrives when Adam supervises the fitting of the cap to the tower.