Converting between rotary and linear motion, and a sawing device

1. An apparatus for converting rotary motion to reciprocating motion, comprising:

a rotatable piece having a surface, the rotatable piece being rotatable about a central axis thereof and the surface having a first cooperating portion in or on the surface;

a member having a linking surface facing the surface of the rotatable piece and arranged for reciprocating movement; the reciprocating movement of the member being along a path which is spaced laterally apart from and which is non-parallel to the central axis of the rotatable piece; and

located between the surface of the rotatable piece and the member, a link configured to link the linking surface of the member and the surface of the rotatable piece, wherein the linking surface of the member has a second cooperating portion extending diagonally on or in the linking surface relative to a direction of the reciprocating movement of the member, and wherein the link links the first cooperating portion to the second cooperating portion;

wherein the link, the first cooperating portion and the second cooperating portion are configured to cooperate so that rotational motion of the rotatable piece in a direction of rotation causes the reciprocating movement of the member repetitively; and

wherein the first cooperating portion is a non-linear continuous first groove, the second cooperating portion is a second groove, and the link comprises a bearing located partially in the first and second grooves.

2. The apparatus of claim 1 , wherein the reciprocating movement of the member is repetitive reciprocating linear movement.

3. The apparatus of claim 1 , wherein the rotatable piece is mounted on a support so as to allow rotation of the rotatable piece about the central axis, and wherein the member is also mounted on the support, the support being configured to restrict the reciprocating movement of the member to a linear path which is spaced from and at least in part transverse relative to the central axis of the rotatable piece.

4. The apparatus of claim 1 , wherein the linking surface and the surface of the member are respectively spaced to retain said bearing in said first and second grooves.

5. The apparatus of claim 1 , wherein said first cooperating portion extends circumferentially around the central axis of the rotatable piece, wherein the radial distance of the first cooperating portion from the central axis is constant.

6. The apparatus of claim 1 , wherein the rotatable piece is substantially cylindrical, and wherein said surface of the piece is the circumferential surface of the substantially cylindrical piece.

7. The apparatus of claim 6 , wherein the reciprocating movement is approximately tangential to the circumferential surface or is in a plane parallel to a plane tangential to the circumferential surface.

8. An apparatus for converting rotary motion to reciprocating motion, comprising:

a rotatable piece having a surface, the rotatable piece being rotatable about a central axis thereof and the surface having a first cooperating portion in or on the surface;

a member having a linking surface facing the surface of the rotatable piece and arranged for reciprocating movement the reciprocating movement of the member being along a path which is spaced laterally apart from and which is non-parallel to the central axis of the rotatable piece; and

located between the surface of the rotatable piece and the member, a link configured to link the linking surface of the member and the surface of the rotatable piece, wherein the linking surface of the member has a second cooperating portion extending diagonally on or in the linking surface relative to a direction of the reciprocating movement of the member, and wherein the link links the first cooperating portion to the second cooperating portion;

wherein the link, the first cooperating portion and the second cooperating portion are configured to cooperate so that rotational motion of the rotatable piece in a direction of rotation causes the reciprocating movement of the member repetitively;

wherein the member comprises a plurality of members; and

the link comprises a plurality of links; and

wherein each of the plurality of members is configured to cooperate with a corresponding one of the plurality of links so that rotational motion of the rotatable piece in the direction of rotation causes the reciprocating movement of the plurality of members repetitively, or the reciprocating movement of the plurality of members repetitively causes rotational motion of the rotatable piece in the direction of rotation.

9. An apparatus for converting rotary motion to reciprocating motion, comprising:

a rotatable piece having a surface, the rotatable piece being rotatable about a central axis thereof and the surface having a first cooperating portion in or on the surface;

a plurality of members each having a linking surface facing the surface of the rotatable piece and arranged for reciprocating movement, the reciprocating movement being along a path which is spaced laterally apart from the central axis of the piece and which is non-parallel to the central axis of the piece; and

located between the surface of the rotatable piece and the plurality of members, a link for each member, configured to link the linking surface of the respective member and the surface of the rotatable piece, wherein the linking surface of each member has a second cooperating portion extending diagonally on or in the linking surface relative to a direction of the reciprocating movement of the respective member, and wherein the link links the first cooperating portion to the second cooperating portion;

wherein each link, the respective first cooperating portion and the respective second cooperating portion are configured to cooperate so that rotational motion of the rotatable piece in a direction causes the reciprocating movement of the plurality of members repetitively.