This pre-1636 Post Mill is owned by Cambridge Preservation Society .

Open days 2009

Contact D. Newson on 01954 719504 or E-mail

WORKING THE BOURN POST MILL.
The body of the mill, the BUCK, contains all the machinery and is balanced on a POST supported by a trestle bolted to four brick piers. Four sails and millstones in front of the post balance the double steps (which act as a thrust support when down) and the tail pole behind (which is used to turn the sails into the wind). The 'Post Mill' is so named from its supporting post.

THE TRESTLE AND MILL CONSTRUCTION.
Thee oaken trestle and post hold the entire weight of the mill and, with the steps, support the enormous thrust of wind on the sails. Note how the sloping quarter bars are 'toothed' into both the post and the crossed beams so that they can take the forces down to the ground through the brick piers. Note also the iron-strapped pegs of the post straddling and gripping the beams, and the bolts holding these beams firmly down to the piers. (not considered necessary when built). Inside the buck the great crown tree is the foundation on which the buck is built and swivels on the post, round a wooden peg in its centre. This is the top bearing, The bottom bearing is formed by the 'shear trees' running from front to back and the sturdy floor of the buck.

TURNING THE MILL INTO THE WIND.
The sails have to face squarely into the wind so the buck, with the weight of all its machinery, has to be turned. First the TALBER (step lever) is pulled down and hooked into place to raise the steps, then the miller pushes the tail pole round and lastly lowers the steps again.

CLOTHING THE SAILS.
The sails will turn without canvas in a strong wind but two 'common sails' (with close slats) can be 'clothed' by threading ringed canvasses on to central steel rods and roping them on to the sails. The other pair were fitted with 'automatic spring shutters' which opened releasing wind pressure when it blew too hard. Only two broken shutters remain of these.

The sails of this mill are due to be repaired by June 2002 with a heritage grant. This will allow the mill to be 'winded' on open days.