BACKGROUND It is known to use portable sawmills to mill logs at remote locations. Examples of prior art sawmills are shown in the patent specifications GB 2,212, 101 (Peterson), WO 97/35697 (Peterson Portable), 248548/250983 (Peterson Portable), US 5,046, 391 (Lewis), and US 5,819, 626 (Lucas). These prior art sawmills each have various advantages and disadvantages. It is an object of the present invention to provide further options for sawmilling, or to at least provide the public with a useful choice.

SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a sawmill having a saw blade which can move between a substantially horizontal cutting position and a substantially vertical cutting position, the sawmill having a control arm which operates to move the blade between the substantially horizontal and vertical cutting positions, the control arm being mounted for pivotal movement about an axis, there being an operating means which acts against the control arm in a substantially linear manner, wherein movement of the operating means causes the control arm to pivot about the axis and move the blade between the cutting positions.

Force applied to move the operating means may be manual, mechanical, hydraulic, or of any other suitable type.

The operating means may be fixed upon a linear function such as a hydraulic ram, electric actuators, a linear bearing race, a threaded linear raceway, or other suitable means of applying a substantially straight force from left to right or between two points.

The blade and control arm may be stopped in a desired position by a stopper means.

Optionally the stopper means is mechanical, electrical or pneumatic in nature.

The operating means may act on one side of the control arm, and thus push the control arm into a first position. The operating means may subsequently act on an opposite side of the control arm to move the control arm into a second position.

Optionally, the control arm may be spring loaded so that when the operating means is released, the control arm returns to the first position.

Preferably the control arm comprises a raceway, wherein the operating means can move against the raceway. Thus the operating means may act directly on the control arm in both the first and second directions by acting on one wall of the raceway in one direction and then an opposite wall of the raceway in the opposite direction.

Preferably the operating means comprises one, two, or more bearings which can contact and move along the raceway.

Preferably an end of the control arm remote from the blade is flared. Preferably when the control arm is in the first position or the second position, the operating

means is positioned above a flared portion of a wall of the raceway, thus effectively providing a locking means. The operating means will not move unless a linear force is applied to it. The flared raceway and operating means stabilise the cutting blade in its position at the time.

Preferably the operating means can act on the control arm to lock the blade in either a vertical or horizontal orientation.

Preferably two separate adjustable bearings are housed in the raceway so that actual locking tension can be independently adjustable in each of the first and second positions.

In a further aspect of the invention there is provided a sawmill, the sawmill having a carriage for moving a saw between two points, the saw having a cutting blade which can move between a substantially vertical cutting position and a substantially horizontal cutting position, the sawmill having a board removal system comprising a deflector mounted adjacent the cutting blade such that when a board has been cut from a log by the sawmill that board is moved from the log by the deflector as another board is being cut from the log adjacent the first mentioned board.

Optionally the deflector can move the board being moved regardless of whether the blade is making a horizontal cut or a vertical cut.

The deflector may move the already cut board when that board is above or to the side of the board in the process of being cut.

Optionally the deflector is mounted adjacent the front or rear of the blade.

Optionally the deflector is in the form of a flap.

Preferably the flap is mounted on a rod. Preferably the position of the flap on the rod can be adjusted to accommodate the size of the board being cut.

The rod may be a threaded rod, driven by a DC motor for automatic setting.

A gauge is preferably mounted onto the rod so that the flap may be positioned precisely.

Preferably, the flap position can be set manually and held in position by a locking means. The locking means may be a star knob, and the flap may be held in a vertical orientation..

The flap is optionally hinged or otherwise moveable so that it may be raised and lowered as required.

Preferably the flap is constructed of metal, but other suitable durable materials may be used.

In a further aspect of the invention there is provided a drive system for a sawmill of the type in which a cutting blade is supported on a carriage, which carriage is arranged for movement along a defined track or tracks, the drive system comprising drive means for moving the carriage in a desired direction along the tracks; means for monitoring the action of the cutting blade, or the motor driving the blade ; and means for controlling the movement of the carriage (eg its speed) in response to changes in operation of the cutting blade.

The driving means may incorporate a clamping means on each side of the carriage to facilitated disassembly of the sawmill and subsequent assembly with accurate blade alignment.

DESCRIPTION OF THE DRAWINGS In order that the invention may be more readily understood, and so that further features thereof may be appreciated, some embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 illustrates a portable sawmill in accordance with one embodiment of the invention, Figure 2 illustrates a blade moving arrangement of the sawmill showing a saw blade in a vertical cutting position, Figure 3 illustrates the blade moving arrangement with the blade in transition between the vertical cutting position and a horizontal cutting position, Figure 4 illustrates the blade moving arrangement when the blade has arrived in the horizontal cutting position, Figure 5 illustrates a power mechanism for the blade moving arrangement, Figure6 illustrates, schematically, the manner of movement of the blade between the vertical and horizontal cutting positions,

Figure 7 illustrates a board removal system of the sawmill, Figure 8 further illustrates the board removal system, Figure 9 illustrates the board removal system showing the blade in the vertical cutting position, Figure 10 illustrates the board removal system showing the blade in transition, and Figure 11 illustrates the board removal system showing the blade in the horizontal cutting position.

DETAILED DESCRIPTION With reference to figure 1, a portable sawmill includes a carriage 1 arranged to be supported upon spaced apart tracks 2 and 3 to co-operate with wheels or rollers 4 mounted at the base or top of the carriage. The tracks 2 and 3 may be supported on skids 5.

The carriage 1 comprises two spaced apart rectangular end frames 6. Each end frame 6 comprises a pair of spaced apart tubular uprights 7 connected by an upper cross member 8 and a lower cross member 9. A substantially rectangular carriage deck 10, that extends, in use, between the end frames 6, is located for upward and downward movement relative to the uprights 7 by way of bushings (not shown). An example of suitable bushings is given in WO 97/35697.

The carriage deck 10 comprises means for mounting a saw with a circular blade 11, of which suitable means are described in the patent specifications GB-A-2212101, NZ 248548/250983, and WO 97/35697. One of the tracks 3 may be in a raised position co-operating with carriage wheels 4 mounted at the upper portion of one end frame 6. As sawdust is expelled to this side, this arrangement avoids interference caused by sawdust build-up around the low track. It also facilitates loading logs under the high track 3 into the mill, reducing the danger of damage to the tracks, during this operation. The carriage 1 comprises drive mechanisms allowing vertical movement of the carriage deck 10 and horizontal or sideways movement of the saw.

With further reference to figure 1, when the sawmill is in use it is arranged with a log 13 between the end frames 6 of the carriage and below the carriage deck 10. The carriage 1 is then run along the tracks 2 and 3 so that the saw blade 11 makes a vertical cut in the log 13. The saw blade 11 is then moved through 90 degrees to assume a horizontal orientation, and the carriage, and thus the blade 11, is moved back along the log to make a horizontal cut which intersects the first cut. In this way a board is cut from the log. The blade 11 is then set back to a vertical orientation, is moved sideways as desired, and the process is repeated continuously until the log is substantially milled into a number of boards. It will of-course be appreciated that the carriage deck 10 is moved downwards during milling after each complete row of boards is cut from the log. Preferably the carriage is clamped as at 9a (figure 1), or otherwise secured, to a chain drive or cable drive to facilitate movement of the carriage along the track.

Figures 2,3 and 4 show the means for moving the blade 11 between the vertical and horizontal orientations or cutting positions. Rotary power is provided to drive

the blade 11 by way of a motor 11 a. Referring to figure 2, the blade 11 is shown set in the vertical cutting position. The blade is mounted on a control arm 14, a medial part of which is in turn mounted for pivotal movement as at 15. The end of the control arm remote from the blade has flared side walls 16 and 17 opposite one another. As shown in figure 2, an operating means, comprising a block 18 slideable on a lineal rail 19 is immediately adjacent the left hand side flared wall 16. The block 18 has two roller bearings 20 set side by side, and fixed against movement other than when they move linearly with the rest of the block. The left hand roller bearing is positioned on top of and against the left hand side wall 16 when the blade 11 is in the vertical cutting position. This serves to lock the control arm 14, and thus the blade 11 in that position.

When it is desired to move the blade 11 to the vertical cutting position the bock 18 is driven along the lineal rail 19 in a horizontal motion to move the left hand bearing away from the left hand side wall 16. This unlocks the control arm 14 and allows it to pivot to swing the blade as shown in figure 3. The block 18 continues to move until the right hand bearing is positioned against and above the right hand side wall 17 as shown in figure 4. This serves to lock the control arm 14 with the blade 11 in the horizontal cutting position. Preferably when the blade is in the horizontal cutting position it can be used to make a horizontal cut from either side of the control arm.

Those skilled in the art will appreciate that movement of the block 18 in the reverse direction will return the blade 11 to the vertical cutting position. For the blade to reach the vertical cutting position the control arm 14 cannot simply be left to swing under gravity, but rather must be forced to move by the block 18, and more particularly by the left hand bearing. In this regard the left hand bearing contacts and runs along the left hand wall 16 to force the control arm around. To facilitate

this the left hand side wall 16 has a curved section which provides a raceway 16a for the left hand bearing.

Figure 5 shows an embodiment of the invention which incorporates a chain drive arrangement 21 used to provide a driving force to move the block 18 along the lineal rail 19. It should however be appreciated that other drive arrangements can be utilized, and in some alternative embodiments the block may be moved manually.

Figure 6 illustrates, schematically, the movement of the control arm 14 and thus the blade 11.

It will be appreciated by those skilled in the art that the sawmill described above provides a linear movement arrangement for moving the blade 11 between vertical and horizontal cutting positions, which is both easy to control and also offers a positive locking means. To appropriately limit the lineal movement of the block 18 and the bearings 20 the sawmill has suitable stoppers positioned at the points marked 22 in figure 2. The stoppers may be mechanical, electrical, or pneumatic, etc, in nature In one embodiment of the present invention there is provided means for removing a cut board from a log as the next board is being cut by a swing blade sawmill. This avoids down-time resulting from having to remove a cut board from the log by hand.

Referring to figure 7, board removal is achieved by way of a deflector in the form of a flap 23 mounted for sliding movement on rods 24 adjacent the front or rear of the saw blade 11. The flap 23 will be mounted adjacent the front or rear of the blade 11 depending on which end of the sawmill the operator wishes the cut boards to be

deposited. The deflector can be used in connection with vertical or horizontal saw cuts. The arrangement is such that when a board has been cut in the log it remains in place until the next board is being cut. As that next board is being cut, with the carriage 1 moving along the log, the flap 23 contacts the board already cut and deflects/pushes it to an end of the sawmill. To facilitate this the carriage is preferably motor driven.

Figure 7 shows the position of the flap 23 in relation to the blade 11 when the blade is in the substantially vertical cutting position. Figure 8 shows the position of the flap 23 when the blade 11 is in the horizontal cutting position. The flap 23 is suspended alongside the blade 11 when the blade is in the substantially vertical cutting position.

The flap 23 is suspended above the blade 11 when the blade is in the horizontal cutting position. As shown, the flap 23 does not overhang the whole width of the blade 11 when in the horizontal cutting position. The width of the blade that the flap 23 does not overhang is used to cut the next board in the log 13.

The flap 23 can be adjusted laterally in the left or right direction along the rods 24.

This allows adjustment to position the flap 23 at the end of a board that has been cut, and allows adjustments for different sized boards. The operator will set the board remover flap 23 adjacent the edge of the board currently being cut. The part of the blade 11 that is not overhung by the flap 23 will be used to cut the next board.

In one embodiment of the invention the flap 23 is associated with the saw side-ways movement facility of the saw such that when the blade moves sideways the flap 23 moves side-ways by substantially the same distance, but in the opposite direction.

This may allow space for a subsequent cut and allow the flap to work against the board just cut..

Preferably a rule or gauge is mounted on at least one of the rods 24 to aid with accurate positioning of the flap 23. Preferably the rods are associated with a power mechanism 25 to mechanically move the flap 23 along the rods, although this is not essential. In some embodiments of the invention the rods 24 may be threaded and driven by a DC motor for automatic setting, etc. Alternatively the flap 23 may be positioned manually and locked in place by a locking means such as a star knob or the like.

The flap 23 is preferably not free to hinge on any of the rods 24, but in some other embodiments of the invention it may be hinged so that it can be raised and lowered as required. The flap is preferably made of metal, although it could be made from other suitable durable materials.

As discussed above, the removal system is designed so that the flap pushes the cut board from the log as the blade makes the next cut in the log while the carriage travels. When the blade reaches the end of the log, the cut board is pushed clear from the log. The blade is then flipped to the vertical position to make a further cut in the board, in doing so the flap will be positioned so that it runs alongside the board being cut, and the carriage moves once again. Once the saw reaches the end of the log, the blade will be flipped to the horizontal position to cut the next board, simultaneously causing the flap to be positioned to remove the cut board when the carriage moves again.

Figures 9,10 and 11 show the flap in various dispositions relative to the saw blade 11.

It will be appreciated that in some embodiments of the invention the flap 23 may be used as a guide as to the depth of a cut. In some embodiments the flap 23 may be capable of vertical adjustment to facilitate removal of a cut board above that being cut at the time.

In some embodiments of the invention the sawmill movement of the carriage 1, the sub carriage 10, the control arm 14, and the flap 23 may be achieved by one or more motors. The motor or motors may be controlled by a CPU so that direction, speed, or degree of movement of the above components can be set or regulated as desired. Preferably the sawmill is such that when the cutting speed of the blade changes significantly during cutting, the speed of the carriage 1 along the tracks 2 and 3 is automatically modified proportionately. For example, if the saw is laboring, and is thus moving more slowly while cutting a hard part of a log, then the speed of the carriage 1 along the tracks 2 and 3 is automatically reduced to allow the blade more time on that particular part of the log. When the blade speed subsequently increases the carriage automatically speeds up as it moves along the tracks.

While some preferred forms of the invention have been described herein, it should be appreciated that modifications and improvements can occur without departing from the scope of the following claims.