Another fun day, even though it was pretty much the same as yesterday. I have now shaped both daggers and dismantled the jig. I had a couple of unexpected problems. Well unexpected is not quite accurate. I had a bow in one of my boards but I thought after attaching the molds to the ends that there was enough overhang to cover it. In just one place there wasn’t. Right on a join there is a gap now about 10mm wide at the widest and about 1mm deep and about 500mm long overall. Its true extent did not become visible until I had finished shaping (although I knew it was there once I had run over the area with the router) and had sanded down all of the corners. I believe that in my attempts to save material I actually cut it a bit fine (no pun intended!). Although I only have a small section to backfill it is still a little more work that I would not have had to do if I had made the strips just a mm or 2 wider. That said, it is not a major problem or a lot of work given I have to backfill the spine anyway. In some places I was shaving just the width of a credit card off. If the router is touching the board along the whole length it does not matter (nor could you ever tell) if you are cutting a mm or a meter except for the amount of waste so this was a good result.
I also had another problem. Whilst turning the blank over to route the other side I dropped the blank off the edge of the table onto the ground a drop of about a meter and a crack opened up in one of the glue lines of the foam strips. It surprised me how much it opened, I would have thought it would have been a hairline crack but it opened up about 1mm. In a way that is also going to help me fix it, I will be able to squeeze glue down into the crack easily. The crack is not a problem, once glued there will be 4 layers of glass over it so it will hardly be an issue, it is just another small piece of work I need to do. In all I have to back fill the small gap in height of the spine both sides, the small low spot and a crack in this dagger and the spines on the other. I also have some holes here and there and some rough areas where the blade ripped rather than cut the foam to fill but for these I will pull a very tight screed (scrape it on very thin) just of thick glue just before I glass and I will glass to it wet on wet once it tacks off a little.
Once I had finished shaping the second blank I dismantled the jig so that I had the bench space back to work on and I sanded off the series of small ridges where the router moved from one level to another. I did yesterdays on the ground, today I got to work at a civilised height. With the second dagger sanded smooth, I finished the shaping of both by cutting the angled top in. The daggers don’t need to be full width for the top third of the length, this will sit above the deck height when raised so it decreases the loss of visibility through it but more importantly it reduces their weight. When lowered this section is inside the case for about half way and full profile section inside the case from about halfway down so that when lowered the dagger is full size from halfway down to the hull bottom exit so that it does not move inside the case.
A sidenote on the jig. I am happy with the way it all worked. Being made out of mdf it started to get sloppy toward the end of the second blank, or the fourth side which is understandable. The height did not alter, I could just feel a little forward and backward movement in the sliding rail so I made a conscious effort to pull or push one way or the other (forward or back) as I slid the rail along, for the whole length of the cut to maintain its consistency of position. No problem. It is not as durable as steel and it was not designed to be so, although I can see where a production builder might want to make up a permanent jig, but all in all I would recommend this method over shaping with a plane or sander. The sheet of mdf cost me $27 and the router bit cost $34. (I still have to buy the sheaves but you need them no matter how you make the daggers) so the daggers cost me about $60 to build this way. I had to sand just the small ridges caused by the changing height of the router bit and this was hard enough. You cannot effectively plane foam with a non power planer either, I tried. So it would have required me using the power plane, not my favourite tool.
Tomorrow I hope to get the fibreglass batten glued into the trailing edge, to do that I have to get the slot cut first.