So, the bowsprit (stick that pokes out of the front) on my sailing yacht got bust in a gale last winter, so I need to make a new one - woodwork in this post, some machined parts to follow...
First, source some clean straight-grained Douglas fir, I need a finished spar of 115mm diameter, so I'm aiming to make a square blank of 120mm, so that's 4 pieces 120 x 30 x 3.7m long. These pieces were laminated together using epoxy, first, a thinned coat wait 30 minutes or so for it to soak in, then an undiluted coat, stack the piece up and use a vacuum bag to clamp the pieces together. The supporting trestles were carefully spaced while the epoxy cured, so the spar (should) be neither sagging nor hogging...
Once cured, the blank was passed through the thicknesser to bring it down to its finished size of 115mm square.
Next, a slot was cut right through at one end to accept the outhaul sheave, this was simply chain drilled, and cut with a chisel as for a mortice and tenon joint. The axel hole was also drilled at this stage.
Next, I made a spar gauge from a scrap of wood, positioning the holes with the mill to make it accurate, and the holes plum. The lines this tool makes are the edges of a perfect octagon. Next step is to make remove the corners with a power planer to make the square section octagonal. Then using a hand plane make the octagon round, then sandpaper to remove the plane marks.
I reckon this job has now generated 1 entire wheelie bin full of wood shavings...