Ok, having a contractor who is a very good trim carpenter as a student can make for an interesting class. He sees things from a different point of view - which is good because it challenges some of our assumptions about how we do things and can allow some "higher order" methods to be tried. I know he reads this blog, so I'm hoping that he has a good sense of humor about this.
As we've discussed before (here and here...) , we make the canoe's bottom as symmetrical panels and cut the center-line of each panel to fit when the panels are off the hull. The major downside to this is that the panel "relaxes" when removed from the hull. One way to get around this is to mark the centerline and to make a several kerfs using a saw while each panel is still on the forms, keeping the teeth vertical. This gives you a series of guide marks to plane to. It works, but still takes a bit of skill and patience.
With guys like this student, it can be one of those, "life seldom separates the men from the toys" experiences. Witness the laser he chose to mark the center-line with:
Makes a nice line - although it is almost a 1/16" wide (.062"). Meh. Quite frankly, it is much wider than I'm comfortable with as a mark. (Particularly when you consider the fact that our Japanese saw blades are only about .020" thick.)
Here is where things went off track a bit. There were two engineers (who are also woodworkers) present with this student. The three of us started to posit how we could do this using a panel or circular saw to cut the centerline without removing the panel from the boat. The basic idea was to create a guide assembly for a saw that would be a consistent distance from the centerline and a consistent height at each form. This is the result of our discussion:
What you can't see is the vertical plywood elements that are screwed to the forms. These vertical elements support the plywood deck. There is a plywood fence screwed to the deck. It is set up so that the distance from the fence to the outer edge of the saw's blade is located at the center-line of the hull. As a test, the first cut was made a bit offset from the centerline (to the right in the image) as can be seen in the picture below:
Once we established that a good cut could be made, the fence was moved over to the center-line and the final cut was made. We have yet to make and cut the second panel, so we'll have to see how things go. So far, the downsides are that the cut passes into the forms (i.e. we'll need to re-tape the forms before building the second panel), it takes a fair amount of time and skill to set-up and you need to be very careful at the ends not to cut into the stems
The verdict is still out, but so far it has been an interesting exercise.
I guess this student gets the , "No guts, not glory" award!