The entire mill has to be rotated to face the wind. To accomplish this two types of tjasker have developed. In the first type, known as "paaltjasker" (English: post tjasker), the mill is supported on and turned around a central post. The Archimedes' screw pumps water from the outer circular ditch to a central circular ditch or pool. The screw moves in a circle when the mill is turned so these circular ditches enable the mill to function in whatever direction it is pointing. Only the outlet from the central pool taking the raised water across the outer circular ditch prevent the use of the mill facing opposite that particular direction as the screw would collide with the water outlet. The second type of tjasker, the "boktjasker" (English: trestle tjasker), is not balanced on a central post but supported on a trestle. The lower submerged support is fixed, the mill is rotated around this point, while the other end is movable. Here the trestle is commonly equipped with rollers or wheels on a fixed ring to make winding easier. In this method of construction the Archimedes' screw takes water from a central pool and deposits it in a circular ditch that surrounds the central pool. Water can be taken to the central pool by a pipe or a gap in the circular ditch. Besides the structural differences, a typical "paaltjasker" is designed so it can relatively easily be dismantled to be moved to another location or stored indoors though nowadays this feature is rarely used. A "boktjasker" is more or less fixed to its location. A third type of tjasker has been rediscovered from old drawings. It has a tail keeping the mill facing in the wind and a scoop wheel instead of an Archimedes' screw. After having built a functional model the reconstruction of a full sized "staarttjasker" (English: tail tjasker) is now planned.