Nearly 16 years ago eight men began restoring a derelict 17th- century Sussex windmill as a labour of love. Now they are opening it to the public for the first time. Tomorrow is the second Sunday in May - the annual date when mill enthusiasts throughout the country hope for a good wind and an equally good response from the public as they throw open their doors and put on special events for National Mills Day.

At Oldland Mill, which sits on a blustery hillock near the West Sussex village of Keymer, it will not be quite like that. Tomorrow's visitors will find the skeleton of the mill swathed in scaffolding, erected by the "intrepid eight" (all now retired) just over a year ago. There are no doors to open because the rotten ones, removed many years ago, have yet to be replaced. Lack of funds and heavy equipment has meant slow progress, so the eight have settled for a steady routine, working one day a week (usually a Thursday) throughout he year.

"When we took on the lease from the county archaeological society in 1980 the building had been untouched since a botched restoration in 1938," said the leader, retired engineer John Annett, 72.

"Although the building still had the appearance of a conventional Sussex post mill - a mill which rotates with the prevailing wind round a single post - the timber exterior was falling off and water had seeped in and rotted much of the oak frame that supports the main structure."

The building was last used commercially in 1919 and when the eight started stripping off the wooden cladding the only part they found substantially intact was the 30ft high round post that forms the centre of the mill.

"It is a magnificent piece of timber, probably original, which has some interesting carved graffiti from succeeding generations of millers. We have been able to save it and are building the rest of the structure round it," Mr Annett said.

The eight have also been able to save the one-and-a-half tonne 25ft-long cast iron windshaft, which was installed when the mill was converted to steam around 1860.

Supported by the scaffolding, it looks like the giant bowsprit of an old ship. Eventually it will be removed for an overhaul before being re- erected to hold the main brake wheel, which Mr Annett and his team plan to reconstruct.

The other giant piece of timber in the mill is the crown tree, an enormous, horizontal slab of oak that supports the whole weight of the structure of the mill as it rotates on a base of four huge oak timbers that form a trestle at the foot of the building.

"Raising this was the only task for which we employed a contractor. Our average age is 65 and it was just too much for us," Mr Annett explained.

"However, using a hand winch we have managed to raise two of the oak frames we have built that form the sides of the building. Each weigh about a tonne.

"The next task is building and raising the other two sides of the frame. One of these - the breast frame - will weigh about one and-a-half tonnes, so we might need help again with the lift."

Most of the framing is built from a job lot of oak Mr Annett bought in 1982 for pounds 6,000. The team cut all the joints by hand. They are fixed together by oak pegs that they have also made.

"We hope to get the main frame complete next year, before turning to the machinery, most of which we salvaged and stored, and the four 22ft long sweeps [sails]," Mr Annett said.

"After that I reckon we have another 10 years ahead of us, making the whole enterprise a 25 year project. By then I calculate that our oldest member will be 92.

"We have no problem producing drawings because two of the team have worked extensively on mills before and it is fairly easy to follow the existing structure. Whenever we are in doubt we consult owners of other surviving post mills."

The main problem the team faces is financial. The work has already cost more than pounds 18,000, which has been raised mainly from village coffee mornings and other local events. "We have not been able to attract any public money because we do not own the freehold of the site," Mr Annett said.

"British Telecom generously gave us pounds 1,500, and another company said they would give us pounds 2,000 pounds a year."

Unfortunately after two years they went broke.

"I reckon that with one cheque for pounds 200,000 we could finish the job and be grinding corn in a couple of years. However carrying on in this way keeps us out of the pubs and off the streets for at least one day a week..."

Oldland Mill can be visited tomorrow: details from Mr Annett on 01273 843573. Information on other mills (some 200) open for National Mills Day can be obtained from the organisers, the Wind and Watermills Section of the Society for the Protection of Ancient Buildings. Telephone 0171- 377 1644 for details.