Builders' Forum Archives
Re: Shearwater hull panel
Posted by CLC on Feb 10, 2007
We do step scarfs on thicker panels, including the Skerry and Jimmy Skiff bottoms and on WoodenBoat Magazine's kits, the Nutshell and Shellback dinghies.
Step scarfs are tricky on really thin panels such as the ubiquitous 4mm plywood. This is because the height of each step is tiny---0.5mm or some such. The MDF surface of the vacuum table on the CNC machine expands and contracts more than that on a humid day so holding such fine depth tolerances on the table top is nearly impossible. It doesn't matter as much on thicker plywood, though even then we have to go through a laborious and time consuming table milling procedure.
The other downside to step scarfs is that they consume a lot of machine time---visualize the cutterhead traipsing back and forth to cut the steps in the step scarfs. Multiply that time out over all the scarfs in a given day's production and we'd never catch up.
In years ahead we'll use a mixture of traditional scarfs, step scarfs, puzzle joints, and butt joints as the situation warrants.
In Response to: Re: Shearwater hull panel by Bob Santore on Feb 10, 2007