Tuesday, May 17, 2011
Tech Tip Tuesday
So, this is a continuation of a previous Tech Tip Tuesday. My student who is building the Wee Lassie II which has been dubbed Wavy Gravy for its sinuous feature strip finished up the second bottom panel at the last class session and set up the jig to cut the panel with a circular saw as he had the first side. Before he made the cut, he set up his laser (above) to see where the cut was going to lie - right in the previous kerf at both ends.
When the cut was made, he erred on the side of caution and cut a kerf width wide. While this wasn't a bad idea, the panels wouldn't fit with this extra material. When the bottom panels are fitted, they need to lay on the forms without "springback". In other words, when you push on the bottom panels where the forms are, it should feel solid, the panel shouldn't flex and spring back up. These are key indications that the panel doesn't fit yet. If there is springback, it is likely that the hull will crack when fairing or sanding the hull. This is a bad situation to be in and we want to avoid it by properly fitted panels.
To make the panels fit, he took a plane to remove material from the second panel. (The first panel was cut exactly to size.) This material is most easily removed when the panel is off the hull forms. While the panel will flatten out slightly, he had cut the panel on the hull, so the bevel angle would vary down the panel length and he could use that bevel as a guide to plane the material away. Quite frankly, I think he did a good job - the hull was tight with the exception of the last 12-14" on one end - it was open a bit at the bottom and will need a either need a little bit of Dookie Shmutz filler or a sliver of cedar to fill the gap.
We also needed to apply a clamp and v-block to hold the panel ends at the proper angle to bond well.
It was also trussed up like a Thanksgiving turkey with inner tubes while the bottom set up.
The results look good so far. Next week, the clamp blocks that are holding the feature strip in place (he didn't want fasteners through the feature strip) will be removed and he will strip up to the sheer line.