Be warned, I'm drinking a tall, cool glass of Pimms while typing this, so if it ends up incoherant you'll know the ratio of Pimms to lemonade was on the strong side...
Right, I promised real pictures of the jig in use, didn't I? Well they're not as clear as they might be but I'll explain.
Most important bit was the use of "blue tak" in the countersink to hold the hemisphere in place. Also big gobs of it under the upper boring guide, which was also clamped in place with a soft-jawed clamp. First time those clamps have actually proved useful... Meanwhile on the backside, a couple of spring clamps hold a bit of lath to lengthen the angle sighting reference. All very colourful, confusing and cluttered. But it did work.
On the whole it'd probably have been easier to break out the 'leccy drill...
Anyway, I finished up the hole boring in the arm, as you may have gathered, and was able to bore the ones in the seat. This may have gone well, or it may not have - I won't know until I start fitting sticks.
Those'll be the sticks I haven't finished yet in fact. Okay, I know I said I wouldn't, but the bulk of the tenon sizing I've done on the lathe. Yes, slow and steady wins the race, but at this rate I'll be coming last in the next race but one so Things Had To Be Done. Still got all the shaping and arm tenon sizing to do on the long sticks though, 'cos a whippy length of 3/4" square stock is not particularly lathe-friendly when you're steady-less. Kinda wish I'd made a rounder now; I did think about it but it never got any further than that.
Anyway, that's the progress. At least it is progress!