First I forgot that the rear surface of the mast is not tapered and ruined one of the staves. Now, when cutting the rabbets, I measured from the fence to the inside of the saw blade instead of the outside! Since I am using a carbide blade, the rabbets on one stave are each about 1/8 inch too wide. Duh!I realized my mistake after making the first two 3/4" cuts, so the 3/8" dimensions on both staves and the 3/4" dimensions on one of the staves are all OK. My thinking is that I can glue the front and back staves to the side stave with the too-wide rabbet, then come back and fill the gap with thickened epoxy and not lose that much strength. I'll have to make sure it is flat at each end to accommodate the filler wood. (The manual shows gluing the two side staves to the back stave first, but I don't think it would make much difference to do it the other way.)
Does this seem feasible? If so should I use silica filler or wood flour thickener, or some combination?
It seems to me that, since the mast is stayed in three directions there is not that much side force on it (as long I keep the stays reasonably tight--just read the post about the forces on the mast actually cracking a tabernacle when the stays were a little too slack).
Please advise.