For anyone who has spiled and cut planks from rough lumber or plywood stock, seeing a computer numerically controlled (CNC) machine make short and precise work of the task is humbling. A few staffers from WoodenBoat Publications had this experience during a visit to Hewes & Company in Blue Hill, Maine, to watch the FlexiCam CNC router cut the first of a series of Iain Oughtred–designed St. Ayles skiffs. Planks with perfectly beveled scarfs were routed from the plywood in a matter of minutes, and programmed alignment holes ensured that the glued scarf joints would yield accurately shaped planks.
Joining us in the shop was Gardner Pickering, head of Hewes’s marine division, and student representative Dylan Brown from Deer Isle-Stonington High School’s Marine Trades Program. [Editor’s note: When this story was originally posted in 2010, the 22′, 330-lb (6.7m, 150-kg) boats were to be built and rowed competitively by local high school students as part of WoodenBoat’s BARC (Boatbuilding & Rowing Challenge).]
Take a look:
First, Gardner Pickering introduced the process and discussed the scarf ratios that were being cut.
Cutting starts after the CNC router automatically selects the appropriate bit from the rack. The first major cut is to establish the scarf angle across one end of the plywood.
Next, the outline of each plank is routed through the plywood sheet.
The planks are easily lifted from the table once the cutter has completed that task.
Pickering checks the shape of the planks and shows how pins through holes keep the shape of the scarfed planks true to the plans.
Pickering shows how the stem and frames are laminated together from multiple CNC-cut parts.
Not captured on camera were the jigs and strongback—also cut to tight tolerances on the CNC router—that allow the builders to dispense with a number of complex tasks, and ensure that all hulls will be very close to the same shape. That’ll be important when the crews start competing on the water. Of course, that accuracy and time saving are exactly the sort of benefits professional shops get when they employ CNC routers to cut station molds and bulkheads for custom boats.
For more on Hewes & Company, see Professional BoatBuilder No. 121, page 24.