The failure of a significant part of the mighty wheel support structure had no quick fix.
In November local engineers Matthew Rawlings and Paul Turnbull were called in to identify why the mill machinery was making unusual noises.
It transpired the main waterwheel bearing on the river side had failed because the large piece of timber supporting it had rotted away.
The huge size of the timber had enabled it to align the bearings while withstanding occasional floods since the centuries-old mill was restored some 40 years ago, but now it was in a state of collapse.
Sourcing parts for an historic mill is a challenge.
Matthew explained: “To replace like-for-like would have required us sourcing a trunk measuring 24 feet in length and two feet square - a sizeable tree.
“In addition, a part of the mill building would have had to be dismantled to allow new timber to be manoeuvred into place.”
In the absence of suitable timber, he designed a fabricated structure which could be fixed to the stonework below and independently adjusted to allow for the alignment of the main waterwheel shaft.
It also allows the bearings to be inundated at times of flooding without the risk of abrasive sediment being deposited in the bearing surfaces.
The new part is fabricated from steel and utilises a material called Vesconite.
“This is a natural polymer formulated for use in quarrying machinery in South Africa’s diamond mines,” explains Matthew, “so it performs well in hostile environments.”
Fully assembled, the new structure weighs around 200kg.
While it was small enough to be lifted through the door, part of the challenge was hauling this weight into position.
Despite the mill wheel being out of action for six months, Heatherslaw Corn Mill has continued to supply flour over the winter as Matthew devised an electric machine to drive the mill stones in the interim.
This temporary fix ensured devotees of Heatherslaw Corn Mill flour could obtain their favourite products. The mill’s flour has been more popular than ever since lockdown, when the heritage machinery worked flat out so that local customers did not suffer from shortages.
Visitors can take a tour and meet Robert Porteous, the new head miller, who has already discovered that running a mill on green energy is a constant battle with the elements.
“We are delighted to have the mill back in full working order, but we could use more rainfall,” he said. “We need enough water in the River Till to keep the wheel turning.”
The next mechanical challenge facing Heatherslaw Corn Mill is the sourcing of a new top stone to enable the mill to grind the grain into flour more efficiently, as the old stone is becoming very worn.
Mill stones are made from French buhrstone, a flint found in France and Belgium. Such mill stones are rare. If anyone knows where a new top stone in good condition can be located, please contact Heatherslaw Corn Mill: [email protected]