Working Drawings

The external circles shall not be cut by the Flatbed Router as these will be deleted prior to cutting commencing. The sole purpose of those circles in the drawings are to ensure that the external shell has an adequate amount of material around it and that they are not been interrupted by the dowels.

The stl. file which was produced on Creo 2.0 is imported onto GeoCAM and the first stage in setting up the programme is to tell the cutter which direction you wish cut. In the above case it is the external part of the sphere which is the desired cut. Alternatively if it is the internal shell of the sphere which was required the axis could be changed which in turn could flip the sphere upside down. As the inside had previously been cut to save machine time it was simply the external shell which needed cut.

The second step in setting up the cutter is to enter the cubic dimensions of the material and the material type which is about to be cut. By entering the material type into the programme it effectively tells the cutter what speed to cut the material at, which would be preset for each material type. In the case of this project the material is Oak however Mahogany has been chosen, as it is a hardwood and all hardwoods are cut at the same speed. 

The images above and below portray how the programme examines the drawing in relation to the material input and also suggests a path through which the cutter will take.

The next step of the programme is simulating the cut. This provides you with an exact preview of the cutters path while also giving you a preview as to whether the cutter will hit the material or if the the cutter will miss the material in any way.

The next step is to clamp the material in the CNC and setting the cutter to the starting point of the material. Co-ordinates of where the cutter should be taken at this point in case of an unforeseen mishap. 

Unfortunately the above file didn't work in its entirety. Although the simulator showed the tool would make the entire cut for the piece the below occured.

It was first thought that it was the bottom of the router which caught on the piece as the cutter height below the router bed was 45mm. (This means that the cutter could make a verticle cut of just 45mm, due to this project being a curved surface it was calculated that the cutter should have achieve the required cut.) I however believe that the cutter height is not the problem due to the simple fact that it is just this side which has been ruined. Should the router cutter be to short it surely would have done the same to the other three corners which are cut to the same depth already. 

Unfortunately mistakes like this seem to occur on the CNC for some apparant reason as can be seen on most other speaker projects. To investigate further this piece was again put onto the CNC to examine the purpose for doing this strange cut. Again it began to cut the same piece leaving all other areas of the piece. 

To overcome this problem I took it upon myself to start from scratch by reducing the cut from 80mm to 40mm and machine two parts which would be glued together. This worked without any faults and so would be problem was overcome.