Dust extractor for planer thicknesser

Abstract

 A planer and thicknesser comprising a frame (26) having a passage way (126) which extends through the frame (26) from one aperture (124) in a wall of the frame (26) to another aperture in a wall of the frame (26); an upper table (20, 28) having a front and rear sections mounted on the frame (26) with a slot (128) between them; a cutting drum (24) rotatably mounted within the frame (26) such that an upper lengthwise section of the periphery of the cutting drum (24) projects upwardly through the slot and a lower lengthwise section of the periphery of the cutting drum (24) projects downwardly into the passage way (126);a motor (100) which rotatingly drives the cutting drum (24) when activated; a lower table (130), substantially parallel to the upper table (20, 28), mounted within the passageway, below the cutting drum (24); and a dust extractor capable of being connected below the upper table (20, 28) when the upper table (20, 28) is being used to support a work piece and capable of being connected above of the upper table (20, 28) when the lower table is being used to support a work piece, and which comprises a box (2), which forms a chamber (10), having an aperture (8) formed through a first side of the box (2) which faces the bottom of the cutting drum (24) when connected below the upper table (20, 28) and faces the top of the cutting drum (24) when connected above the top surface of the upper table (20, 28); characterised in that the dust extractor comprises two chutes (4, 6) which are connected to a second side of the box (2) and which project away from the box (2), each chute (4, 6) forming a passageway (12, 14) which connects to the chamber (10).

Description

[0001] The present invention relates to a planer and thicknesser and to a dust extractor for a planer and thicknesser.

[0002] A typical planer and thicknesser comprises a box like frame comprising a horizontal rectangular upper table and a base connected to each other along their longer sides by two side walls. The horizontal upper table is located directly above the rectangular base. A first aperture is formed by one of the shorter ends of the upper table and by the base and one end of each of the two side walls. Similarly, a second aperture is formed on the opposite side of the rectangular box frame by the other shorter end of the upper table and the other end of the base, together with the other ends of each of the side walls. A passage way connects the two apertures to each other.

[0003] The upper table is constructed from two rectangular sections, a front section and a rear section. The two sections of the upper table are constructed from single rectangular sheets of metal having smooth top surfaces. The top surface of the front section is parallel to the top surface of the rear section. Both the top surfaces are smooth so I that a work piece can be slid across their surfaces. The height of the front section can be adjusted relative to the height of the rear section. The two sections are separated by a slot.

[0004] A horizontal lower table is located movably within the passage way. The plane of the lower table is parallel to that of the upper table. The lower table is constructed as a single rectangular sheet of metal having a smooth top surface. The lower table extends through the full length of the passage way from the first aperture to the second aperture. The width of the table is slightly less than that the width of the passage way. The table is mounted in such a manner that it can be moved vertically upwards or downwards, the top surface of the table remaining horizontal at all times during this process.

[0005] A cutting drum is rotatably mounted between the two side walls in such a manner that its axis of rotation is perpendicular to the plane of the side walls and parallel to the planes of the upper and lower tables. The cutting drum can be rotatably driven by an electric motor mounted within the base. The axis of rotation of the cutting drum is located below the upper table.

[0006] A part of the periphery of the cutting drum along its length extends upwardly through the slot between the front and rear sections of the upper table.

[0007] Each of two cutting blades are mounted within a groove of the cutting drum which runs along the length of the cutting drum in well known manner parallel to the axis of rotation. The cutting blades of the cutting drum can be used to cut work pieces in well known manner which are either slid across the upper table in one direction or are slid across the lower table in the other direction.

[0008] The cutting drum is located so that, as the cutting drum rotates, the maximum height of the cutting blade mounted within the cutting drum through the slot is approximately the same as that of the height of the rear section of the upper table, the height of the rear section being fixed relative to the frame.

[0009] Two drive rollers are mounted on either side of the cutting drum between the side walls in such a manner that their axes of rotation are parallel to that of the cutting drum. The two drive rollers are rotatably driven by the same electric motor which is used to drive cutting drum. The function of the two drive rollers is to force any work pieces which are fed into the rectangular passageway to slide across the lower table and engage with the cutting blades at the lowest point as the rotating cutting drum rotates.

[0010] A planer and thicknesser can be used in two different modes of operation. In the first mode of operation, a workpiece is slid across the upper table in order to remove the surface of the work piece which is adjacent to the smooth top surface of the upper table. The height of the front section of the upper table determines the amount of material which is to be removed from the work piece. First, the height of the front section is adjusted so that the cutting action of the rotating drum removes the right thickness of material from the lower surface of the work piece. Second, the cutting drum is then rotatingly driven by the electric motor. Whilst the cutting drum is rotating, the work piece is then slid across the front section of the upper table until it engages with the cutting blade of the cutting drum as it rotates, which repeatedly passes through the slot between the front and rear sections . It is then pushed onto the rear section of the upper table across the rotating cutting drum. As the work piece passes over the rotating blades of the cutting drum, the cutting blades remove material from the underside of the work piece. The debris generated by the cutting action of the blades are ejected into the passage way below the upper table.

[0011] In the second mode of operation, a work piece is slid across the smooth surface of the lower table in order to remove the top surface of the work piece. The height of the lower table within the passageway determines the amount of material which will be removed from the top surface of the work piece as it is passes through the passageway. First, the height of the lower table is adjusted so that the cutting action of the rotating drum removes the correct thickness of material from the top surface of the work piece. Second, the cutting drum is then rotatingly driven by the electric motor. Whilst the cutting drum is rotating, the work piece is slid across the lower table, until the upper surface of the work piece engages with the rotating cutting blades of the cutting drum as a cutting drum rotates. As a work piece passes under the cutting blades, cutting blades remove material from the topside of the workpiece. The two drive rollers, which are also being rotatingly driven by the electric motor force the work piece through the passageway. The debris generated by the cutting action of the blades are ejected through the slot between the front and rear sections of the upper table and onto the top surface of the front section.

[0012] EP1570964 describes such a planer thicknesser, and in particular, EP1570964 describes a dust extractor for a planer thicknesser. The dust extractor disclosed in EP1570964 comprises a single chute 254 through which debris is ejected during the cutting operation. As such, when the dust extractor is used in the first mode of operation, it is connected to the underside of the rear section 16 of the upper table. When the dust extractor is used in the second mode of operation, it is connected to the topside of the front section 14 of the upper table. This requires that a set of connection points 258, 260 for the dust extractor needs to be provided at the front and rear of the planer thicknesser.

[0013] It is one object of the present invention to provide a design of dust extractor which enables only one set of connection points to be provided on the planer thicknesser to attach the dust extractor to the planer thicknesser either above the upper table or below the upper table.

[0014] Europe has introduced new safety legislation in relation to planer thicknessers. It is now a requirement that the dust extractor must be fitted at all times when it is in use. Therefore, a locking system needs to be added which detects whether the dust extractor has been fitted and which prevents the operation of the planer thicknesser if it has not been fitted.

[0015] A second object of the present invention is to provide such a locking system.

[0016] According to a first aspect of the present invention, there is provided a planer and thicknesser comprising a frame having a passage way which extends through the frame from one aperture in a wall of the frame to another aperture in a wall of the frame;

an upper table having a front and rear sections mounted on the frame with a slot between them;

a cutting drum rotatably mounted within the frame such that an upper lengthwise section of the periphery of the cutting drum projects upwardly through the slot and a lower lengthwise section of the periphery of the cutting drum projects downwardly into the passage way;

a motor which rotatingly drives the cutting drum (24) when activated;

a lower table, substantially parallel to the upper table (20, 28), mounted within the passageway, below the cutting drum; and

a dust extractor capable of being connected below the upper table when the upper table is being used to support a work piece and capable of being connected above of the upper table when the lower table is being used to support a work piece, and which comprises a box, which forms a chamber, having an aperture formed through a first side of the box which faces the bottom of the cutting drum when connected below the upper table and faces the top of the cutting drum when connected above the top surface of the upper table;

characterised in that the dust extractor comprises two chutes which are connected to a second side of the box and which project away from the box, each chute forming a passageway which connects to the chamber.

[0017] By providing a dust extractor with two cutes, it can attach to one set of attachment points at one end of the planer only, regardless of whether the planer thicknesser is being used in its first or second mode of operation.

[0018] According to a second aspect of the present invention, there is provided a dust extractor for a planer and thicknesser comprising a frame having a passage way which extends through the frame from one aperture in a wall of the frame to another aperture in a wall of the frame;

an upper table having a front and rear sections mounted on the frame with a slot between them;

a cutting drum rotatably mounted within the frame such that an upper lengthwise section of the periphery of the cutting drum projects upwardly through the slot and a lower lengthwise section of the periphery of the cutting drum projects downwardly into the passage way;

a motor which rotatingly drives the cutting drum when activated;

a lower table, substantially parallel to the upper table, mounted within the passageway, below the cutting drum;

wherein the dust extractor comprises a box, which forms a chamber, having an aperture formed through a first side of the box characterised in that the dust extractor comprises two chutes which are connected to a second side of the box and which project away from the box, each chute forming a passageway which connects to the chamber.

[0019] Such a dust extractor can have the two chutes connected to the box adjacent each other on the opposite side of the box to where the aperture is formed.

[0020] The chutes can extend from each other as they extend away from the box. The chutes can extend at 90 degrees to each other from each other as they extend away from the box.

[0021] The dust extractor can further include a connector mounted on box which comprises a threaded rod. The threaded rod can be rotatably mounted on the box in a non removeable manner. The thread of the rod can be a non standard pitch. Alternatively or in addition the thread of the rod can be in a reverse direction to that of a standard pitch.

[0022] An embodiment of the present invention will now be described with reference to the accompanying drawings of which:

Figure 1 shows a perspective view of the dust extractor located the front section of the upper table;

Figure 2 shows the underside of the dust extractor;

Figure 3 shows a side view of the dust extractor located the front section of the upper table;

Figure 4 shows a second perspective view of the dust extractor located the front section of the upper table;

Figure 5 shows a top view of the connection point with a sensor;

Figure 6 shows a side view of the connection point with a sensor;

Figure 7 shows a plastic guard;

Figure 8 shows the plastic guard attached to the edge of the front section of the upper table;

Figure 9 shows a schematic view of the vertical cross section of planer thicknesser with the dust extractor located above and below then rear section of the upper table; and

Figure 10 shows a schematic diagram of a cross sectional view of the connection point with a sensor;

Figure 11 shows a diagram of the control system for the motor; and

Figure 12 show a perspective view of a schematic diagram of a planer thicknesser.

[0023] The planer thicknesser described in the embodiment is similar to that described in EP1570964 except for the design of dust extractor, the mechanism by which it is attached to the frame of the planer thicknesser, the electric circuit for the motor, and the addition of a locking system which detects whether the dust extractor has been fitted and which prevents the operation of the planer thicknesser if it has not been fitted.

[0024] Referring to Figure 12, the planer and thicknesser comprises a box like frame 26 comprising a horizontal rectangular upper table 20, 28and a base 120 connected to each other along their longer sides by two side walls 122. The horizontal upper table is located directly above the rectangular base 120. A first aperture 124 is formed by one of the shorter ends of the upper table 20, 28 and by the base 120 and one end of each of the two side walls 122. Similarly, a second aperture (not visible) is formed on the opposite side of the rectangular box frame 126 by the other shorter end of the upper table 20, 28 and the other end of the base 120, together with the other ends of each of the side walls 122. A passage way 126 connects the two apertures 124 to each other.

[0025] The upper table is constructed from two rectangular sections, a front section 28 and a rear section 20. The two sections 20, 28 of the upper table are constructed from single rectangular sheets of metal having smooth top surfaces. The top surface of the front section 28 is parallel to the top surface of the rear section 20. Both the top surfaces are smooth so I that a work piece can be slid across their surfaces. The height of the front section 28 can be adjusted relative to the height of the rear section 20. The two sections are separated by a slot 128.

[0026] A horizontal lower table 130 is located movably within the passage way 126. The plane of the lower table 130 is parallel to that of the upper table 20, 28. The lower table 130 is constructed as a single rectangular sheet of metal having a smooth top surface. The lower table 130 extends through the full length of the passage way 126 from the first aperture 124 to the second aperture. The width of the table 130 is slightly less than that the width of the passage way 126. The table 130 is mounted in such a manner that it can be moved vertically upwards or downwards, the top surface of the table 130 remaining horizontal at all times during this process.

[0027] A cutting drum 24 is rotatably mounted between the two side walls 122 in such a manner that its axis of rotation is perpendicular to the plane of the side walls 122 and parallel to the planes of the upper and lower tables. The cutting drum 24 can be rotatably driven by an electric motor 100 mounted within the base 120. The axis of rotation of the cutting drum 24 is located below the upper table 20, 28.

[0028] A part of the periphery of the cutting drum 24 along its length extends upwardly through the slot 128 between the front 28 and rear 20 sections of the upper table.

[0029] Each of two cutting blades 132 are mounted within a groove of the cutting drum 24 which runs along the length of the cutting drum 24 in well known manner parallel to the axis of rotation. The cutting blades 132 of the cutting drum 24 can be used to cut work pieces in well known manner which are either slid across the upper table 20, 28 in one direction or are slid across the lower table 130 in the other direction.

[0030] The cutting drum 24 is located so that, as the cutting drum 24 rotates, the maximum height of the cutting blades 132 mounted within the cutting drum 24 through the slot 128 is approximately the same as that of the height of the rear section 20 of the upper table, the height of the rear section 20 being fixed relative to the frame 26.

[0031] The electric circuit for the motor will now be described.

[0032] Referring to Figure 11, the planer thicknesser comprises control electronics 102 which is connected to a motor 100. The motor 100 rotatingly drives a cutting drum 24 in order to allow the planer thicknesser to operate in its first or second modes of operation. The control electronics 102 control the operation of the motor 100 which is powered by the control electronics via electric cables 104. The control electronics 102 controls the voltage and current signal to the motor to control its speed and torque out put. The control electronics 102 is connected to a mains power supply 106 via electric cables 108. An ON/OFF switch 110 is electrically connected to the control electronics 102 via electric cables 112. The ON/OFF switch 110 is mounted on the frame 26 of the planer thicknesser. Activation of the ON/OFF switch 110 by tan operator sends a signal to the control electronics 102 to cause it to drive the motor 100. A micro switch 36 (described in more detail below) 110 is electrically connected to the control electronics 102 via electric cables 114. The micro switch 36, when activated, sends a signal to the control electronics 102. The control electronic is configured so that it will only operate the motor 100 in a normal driving mode if the micro switch 36 is activated. If the micro switch 36 is not activated, the control electronics can be configured to either 1) prevent the operation of the motor 100, 2) provide sufficient voltage and/or current to the motor 100 to cause it to hum or buzz (providing an indication to the operator that the micro switch has not been activated) or 3) drive motor 100 at a very slow rate (providing an indication to the operator that the micro switch has not been activated).

[0033] A detailed description of the new design of dust extractor will now be described.

[0034] Referring to Figures 1 to 4, the dust extractor comprises a tubular body 2 of rectangular cross section and which provides a first passageway 10. Two chutes 4, 6 are attached at one end of the body 2 and on one side of the body 2, adjacent each other. Both chutes are tubular with a rectangular cross section having the same dimensions as the body 2. Each chute 4, 6 provides another passageway 12, 14. The first chute 4 extends forward at angle of 45 degrees to the body 2. The second extends rearward at angle of 45 degrees to the body, the two chutes extending at 90 degrees relative to each other. A large aperture 8 is formed on the opposite side of the body 2 to where the chutes 4, 6 are attached and where the passageways 10, 12, 14 inside of the two chutes 4, 6 and body 2 meet. Two parallel connection arms 16 are attached to either side of the body 2. The connection arms 16 connect to two connection points 22 on the frame 26 of the planer and thicknesser, each using a bolt 18. The bolts are attached to the arms 16 in such a manner that they can be rotated to attach them to the connection points 22 but can not be removed from the arms 16. As such, the bolts 18 remain permanently attached to the arms 16. The connection points are described in more detail below.

[0035] The operation of the dust extractor will now be described with reference to Figure 9.

[0036] When the planer thicknesser is used as a thicknesser, (second mode of operation) the dust extractor is placed on top of the rear section 20 of the upper table, shown as position 1. Each of the arms 16 is attached using the bolts 18 to the connection points 22 on the frame 26 located on either side of the rear section 20 of the upper table. A cutting drum 24 is located between the rear section 20 of the upper table and the front section 28 of the upper table and rotates in the direction of Arrow A. A work piece is fed into the body 26 of the planer thicknesser underneath the rear section 20 of the upper table in the direction of Arrow B until it engages the drum 24. The rotating cutting drum 24 cuts the top surface of the work piece and the wood chips created are expelled from the planer thicknesser through the dust extractor. The wood chips pass through the aperture 8 and then through the passageway 12 in the first chute 4 and then is expelled from the first chute in a direction indicated by Arrow C. The first chute 4 is arranged to extend away from the tubular body 2 in a direction perpendicular to the axis of rotation of the cutting drum and in the same direction that the wood chips are expelled from the cutting drum 24 as it cuts the work piece. This provides a straight passage for the wood chips to pass through, the straight passage comprising the aperture 8, the chamber inside of the tubular body 2 and the passageway in the chute 4.

[0037] When the planer thicknesser is used as a planer (first mode of operation), the dust extractor is placed underneath the rear section 20 of the upper table, shown as position 2. Each of the arms 16 is attached using the bolts 18 to the same connection points 22 located on either side of the rear section 20 of the upper table. The cutting drum 24 rotates in the same direction, the direction of Arrow A. A work piece is fed onto the front section 28 of the upper table in the direction of Arrow D until it engages the drum 24. The rotating cutting drum 24 cuts the bottom surface of the work piece and the wood chips created are expelled from the planer thicknesser through the dust extractor. The wood chips pass through the aperture 8 and then through the passageway 14 in the second chute 6 and then are expelled from the second chute 6 in a direction indicated by Arrow E. The second chute 6 is arranged to extend away from the tubular body 2 in a direction perpendicular to the axis of rotation of the cutting drum 24 and in the same direction that the wood chips are expelled from the cutting drum 24 as it cuts the work piece. This provides a straight passage for the wood chips to pass through, the straight passage comprising the aperture 8, the chamber inside of the tubular body 2 and the passageway in the chute 6.

[0038] The use of two chutes 4, 6 enables the dust extractor to connected at one end of the planer thicknesser, either above or below the rear section 20 of the upper table, thus allowing only one set of connection points to be required.

[0039] The connection points used for attaching the dust extractor either above the rear section of the upper table28 or below the rear section 20 of the upper table will now be described.

[0040] The first connection point (not shown) comprises a simple threaded tubular passage formed in the frame 26 into which one of the bolts 18 screws to secure the arm 16 to that connection point.

[0041] The second connection point comprises a sensor and will now be described with reference to Figures 5, 6, 10 and 11.

[0042] The connection point comprises two sections, a front section 30 and a rear section 32 rigidly attached to the front section. The front section 30 comprises a threaded passage 34 into which the bolt 18 can be screwed. The rear section 32 forms a micro switch housing in which is mounted the micro switch 36. The micro switch 36 comprises a button 38 which can move between an outer position where it projects out of the micro switch and an inner position where it is located inside the micro switch 36. The button 38 is biased by a spring to its outer position. Depression of the button 38 sends a signal to the control electronics 102 of the planer thicknesser. The micro switch 36 is located in the rear section 32 so that the button 38 faces towards the end of the threaded passage 36. When the bolt 18 is screwed into the threaded passage 36 to its maximum extent, it engages with the button 38 and pushes it to its inner position. Thus, when the bolt 18 is secured to the connection point in order to attach the dust extractor, it activates the micro switch 36 which sends a signal to the control electronics 102. This allows the control electronics 102 to activate the motor on the planer thicknesser and operate it in a normal driving mode. Removal of the bolt 18 deactivates the micro switch 36 which stops sending a signal to the control electronics 102 which in turn either 1) prevents the operation of the motor 100, 2) provides sufficient voltage and/or current to the motor 100 to cause it to hum or buzz whilst being unable to rotate (thus providing an indication to the operator that the micro switch 36 has not been activated and therefore the dust extractor is not attached) or 3) drive motor 100 at a very slow rate and/or torque which would result in the cutting drum in rotating but being unable to cut anything (thus providing an indication to the operator that the micro switch 36 has not been activated and therefore the dust extractor is not attached).

[0043] The thread of the two bolts 18 and the threaded passages 34 of the first and second connection points is either of a non-standard and/or reversed pitch to prevent the user simply inserting a standard bolt to over ride the system.

[0044] The connection point is secured to a metal post 50 attached to the frame 26 with the rear section 32 located inside it.

[0045] The design of the edges 40 (see Figure 9) of the front and rear tables 20, 28 has also been changed. The front edges 40 are presently flat. It is now intended to add a curved plastic guard 42 to each of them as shown in Figure 7 and 8. This will improved the performance of the wood chip removal.

Claims

1. A planer and thicknesser comprising a frame (26) having a passage way (126) which extends through the frame (26) from one aperture (124) in a wall of the frame (26) to another aperture in a wall of the frame (26);
an upper table (20, 28) having a front and rear sections mounted on the frame (26) with a slot (128) between them;
a cutting drum (24) rotatably mounted within the frame (26) such that an upper lengthwise section of the periphery of the cutting drum (24) projects upwardly through the slot and a lower lengthwise section of the periphery of the cutting drum (24) projects downwardly into the passage way (126);
a motor (100) which rotatingly drives the cutting drum (24) when activated;
a lower table (130), substantially parallel to the upper table (20, 28), mounted within the passageway, below the cutting drum (24); and
a dust extractor capable of being connected below the upper table (20, 28) when the upper table (20, 28) is being used to support a work piece and capable of being connected above of the upper table (20, 28) when the lower table is being used to support a work piece, and which comprises a box (2), which forms a chamber (10), having an aperture (8) formed through a first side of the box (2) which faces the bottom of the cutting drum (24) when connected below the upper table (20, 28) and faces the top of the cutting drum (24) when connected above the top surface of the upper table (20, 28);
characterised in that the dust extractor comprises two chutes (4, 6) which are connected to a second side of the box (2) and which project away from the box (2), each chute (4, 6) forming a passageway (12, 14) which connects to the chamber (10).

2. A planer and thicknesser as claimed in claim 1 wherein the dust extractor is connected below the underside of the rear section (20) of the upper table (20, 28) when the upper table is being used to support a work piece and is connected above the rear section (20) of the upper table when the lower table (130) is being used to support a work piece.

3. A planer and thicknesser as claimed in any one of the previous claims wherein the two chutes (4, 6) connect to the box (2) adjacent each other on the opposite side of the box (2) to where the aperture (8) is formed.

4. A planer and thicknesser as claimed in any of the previous claims wherein the chutes (4, 6) extend from each other as they extend away from the box (2).

5. A planer and thicknesser as claimed in claim 4 wherein the chutes (4, 6) extend at 90 degrees to each other from each other as they extend away from the box (2).

6. A planer thicknesser as claimed in any one of the previous claims wherein, when the dust extractor is connected below the upper table (20, 28) or above the upper table (20, 28), both of the chutes (4, 6) extend away from box (12) in a direction perpendicular to the axis of rotation of the cutting drum 24.

7. A planer thicknesser as claimed in any one of the previous claims wherein, when the dust extractor is connected below the upper table (20, 28) or above the upper table (20, 28), a straight passageway is formed through both of the chutes (4, 6) which extends from the cutting drum 24 through the aperture (8), through the chamber (10) and through the passageways (12, 14) formed within each chute (4, 6).

8. A planer thicknesser as claimed in any one of the previous claims wherein, when the dust extractor is connected below the upper table (20, 28) or above the upper table (20, 28), one of the two chutes (4, 6) extends away from box (12) in the same direction that debris, generated by the cutting action of the cutting drum, would be expelled from the cutting drum.

9. A planer thicknesser as claimed in any of claims 1 to 8 wherein there is provided a set of first connectors (18) mounted on the dust extractor and a second set of connectors (22) mounted on the frame (26), the number of first connectors (18) provided being equal to the number of second connectors (22) provided, wherein every first connector (18) lockingly engages with a second connector (22) when the dust extractor is connected below the upper table (20, 28) or when the dust extractor is connected above the upper table (20, 28).

10. A planer and thicknesser as claimed in claim 9 wherein one of the first or second connectors comprises a threaded rod (18) and the other connector comprises a threaded passage (34).

11. A planer and thicknesser as claimed in claim 10 wherein the threaded rod (18) is rotatably mounted on the dust extractor or frame (2^) in a non removeable manner.

12. A planer and thicknesser as claimed in either of claims 10 or 11 wherein the thread of the rod (18) and passage (34) is of a non standard pitch.

13. A planer and thicknesser as claimed in any of claims 10, 11 or 12 wherein the thread of the rod (18) and the passage (34) is in a reverse direction to that of a standard pitch.

14. A planer and thicknesser as claimed in any of claims claim 10 to 13 further comprising:

control electronics (102) which controls the motor (100);

a micro switch (36), electrically connected to the control electronics (102), located adjacent the end of the passage (34) of one pair of first and second connectors and which is engaged by the end of the threaded rod (18) when the threaded rod (18) is screwed into the threaded passage (34),

wherein the micro switch (36) provides a signal to control electronics (102) to indicate whether it is engaged with the end of the threaded rod (18) or not, the control electronics (102) allowing the motor (100) to operate as normal when the micro switch (36) indicates that the threaded rod (18) is engaged with the micro switch (36) and hindering the normal operation of the motor 100) when the micro switch (36) indicates that the threaded rod (18) is not engaged with the micro switch (36).

15. A planer and thicknesser as claimed in claim 14 wherein the control electronics (102) hinders the normal operation of the motor (100) by preventing the operation of the motor (100), or by providing sufficient voltage and/or current to the motor (100) to cause it to hum or buzz whilst being unable to rotate, or by allowing the drive motor (100) to rotate at a very slow rate and/or torque.

16. A dust extractor for a planer and thicknesser comprising a frame (26) having a passage way (126) which extends through the frame (26) from one aperture (124) in a wall of the frame (26) to another aperture in a wall of the frame (26);
an upper table (20, 28) having a front and rear sections mounted on the frame (26) with a slot (128) between them;
a cutting drum (24) rotatably mounted within the frame (26) such that an upper lengthwise section of the periphery of the cutting drum (24) projects upwardly through the slot and a lower lengthwise section of the periphery of the cutting drum (24) projects downwardly into the passage way (126);
a motor (100) which rotatingly drives the cutting drum (24) when activated;
a lower table (130), substantially parallel to the upper table (20, 28), mounted within the passageway, below the cutting drum (24);
wherein the dust extractor comprises a box (2), which forms a chamber (10), having an aperture (8) formed through a first side of the box (2) characterised in that the dust extractor comprises two chutes (4, 6) which are connected to a second side of the box (2) and which project away from the box (2), each chute (4, 6) forming a passageway (12, 14) which connects to the chamber (10).

Drawing