We’ll give it a shot… (day 49)

It’s been challenging to make headway this week, just a lot going on. As always, just got to keep at it as well as I can. Last time I reworked the polycap installation for the midriff joint, and lamented the fact that the connecting rods installed in the midriff were still so far out of whack. Today I used a guide to reinstall the rods with better alignment, and also made some adjustments to the chest block for better symmetry.

Because the connecting rods for the midriff joint were installed manually and independently of each other, they wound up a bit misaligned. This kind of misalignment causes stress on the joint and limits its range:

I figured the best way to deal with this would be to tear out the rods (again!), widen their mounting holes in the midriff part, and create a jig to hold two rods parallel at the proper distance, and then use that to rebuild the mounting holes.

Unfortunately on the first attempt I made a mistake – I tried to figure out the correct angle and position for the rods myself and jump straight to setting the new mounting holes with the guide, and wound up with holes that were at too-shallow an angle, and a non-functional joint. So I basically tore out that work and did it again: This time by first setting the mounting hole for the left side by connecting the midriff to the torso, then using the alignment jig to set the right-side mounting hole to match the left:

I’ll need to wait for the epoxy putty to cure before I can see how well that work turned out. In the mean time, I decided to make some more adjustments to the chest block symmetry. All the work I did last time that didn’t really pan out – that aligned the top of the chest but misaligned all the rest of the chest… I undid that. I decided to bulk up the top panel of the right-side chest block shell by 1/2mm, and then trim the same amount of thickness off the outer surface.

Finally, after consulting the reference art a bit I decided that the portions of the cockpit canopy that descend around the sides of the hatch should be narrower – which in turn means that the cockpit hatch itself should be wider to fill the space. I adjusted the canopy a bit and did another application of epoxy putty to the hatch.

It’s tricky trying to solve symmetry problems: I use one set of features to align the two parts and use that alignment to check another set of features… But everything is going to be a little bit misaligned, so there’s no real reliable reference point. This is what makes clearly-established centerlines so valuable, you get a reference point that can be the arbiter of any symmetry questions… But for a part like the chest block shell, which is not itself (as a single half) symmetrical and so doesn’t have a centerline… It’s kind of difficult.

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