CNC (Computer Numeric Control) machine are more and more common. For example, companies making signalling panels are frequently equipped. This allows a boat-builder, amateur or professional, to sub-contract the cutting to a local company. This may be very useful in countries or areas where I have not any kit supplier partner.
For that purpose, I am now selling CNC files for many boats. These files, (dxf format) are readable by all CAD software. I have made them in order to be compatible with most CNC machine. Therefore, it is not frequent to get technical troubles. If any, I will modify the files, and, if unsuccessful, I will refund the files price. Most parts are cut at the final dimension. Hull strakes have some extra length at both ends. Deck parts, having a double curvature, have a margin all around allowing adjustment when laid down.
There are several cutting techniques: mechanical routers, laser or water jet. I prefer mechanical routers. The laser burns the plywood edges and may reduce the epoxy adherence. Water jet wet the plywood and, if the parts are stacked not fully dry, may cause damages. The files are generally made for a maximum 8 mm tool diameter. As a rule, the nesting of parts is made into 2.44 x 1.22 m (8′ x 4′) panels, which is the most common size in the world.
The length to be cut for one boat is several hundreds of meters. For example, there are 440 m to be cut for an Ilur. CNC cutting saves a big amount of working time. Just imagine the time required to mark the parts on the plywood panels, cut them with a jigsaw mostly at arm’s length, fair the edges with a plane for such a length! that is why I strongly recommend CNC cutting. Actually, the plans of my larger boats do not include dimensioned drawings and only CNC cutting is proposed. This is due to the fact the building process is optimised for that.