1:100 Zaku Kai (ザク改) - Backpack Construction
Most 3-D adaptations of the Zaku Kai backpack tend to make it very large and boxy. I felt the lineart indicated a sleeker form, and so I tried to emphasize that, and so made the backpack relatively thin, front-to-back, and with most of its planes at some kind of an angle. My design for the backpack has gone through a few revisions - at one point I examined the Blender version and found it to be too boxy, and so adjusted various edges to make it sleeker-looking - and then later discovered that I had already made a similar set of changes to the paper plans. Heh.
This version of the backpack part was taken straight from the Blender model - parts laid out on .5mm styrene sheet, cut out and assembled. I did find it to be a bit tricky to lay out the parts for the inside of the backpack so they could be added to the outer shell which had already been built. The assembled backpack is pretty good, I think, but it still needs work - gaps that appeared in the assembly need filling, and some of the planes need to be re-planed before detail can be added to the part.
There were some issues with my previous attempt at building the
backpack: some angles weren't quite correct, some of the places
where plates were joined inside the backpack were kind of sloppy
(featuring gaps and, later, excessive filler) so I decided to
start over using what I learned about box joins vs. mitre joins
when I was building the chest block insert... In addition, I
decided to lay out a more complete plan for how the parts would
be constructed, and how exactly they should be shaped. Here are
the results so far:
Key changes in this version are the use of box joins to attach plates wherever possible: there are very few mitre joins on this version. The other thing I've learned which I'll be applying to the new part is that it's easier to create clean right angles on plate edges by cutting the edges slightly oversized and then sanding them down... The quality of part edges was one of the more significant problems with my earlier build, so I'll be pleased to improve on that this time around.
Additionally, I reorganized the internal construction a bit: One of my concerns with the first build was that the left and right thruster wells weren't at the same angle. This time, two of the three plates that form the thruster well on each side will go all the way across, which should make it easier to ensure that the angles in those areas are consistent.
I started a second version of the backpack based on the new construction plans: however, careless work introduced a few visible errors, so I decided to start again, and be more careful in the new attempt. Particularly, I want to be very sure that matching parts for the left and right sides match as closely as possible, that all 90 degree joins really are at 90 degrees, etc. It makes progress go a little more slowly, but I am learning that it's still faster than scrapping a part and starting over again.
Most of the work so far has gone into the center thruster housing of the backpack: the plates are the same design as those used in the previous attempt, but this time I glued them to each other before doing the final edge-sanding, to help make the two parts match up better, and then cut them apart again for assembly. I added additional plates perpendicular to the side plates in order to help lend the part a stronger structure and a more consistent spacing, and I squared up the major joins as I made them. Some bits of precision were still a matter of eyeballing the part, hopefully that will be good enough. In order to position the part within the rest of the backpack, I added another couple of spacer plates to the interior of the structure, to help ensure that the thruster housing winds up in its proper place in the end.
One fairly major problem I had with the second attempt was the side plates of the backpack: I designed them out of .5mm plate so each plate could be made of two layers stacked: in this way I hoped to create the part's mitred edge as part of the plate layout... However, small mistakes in cutting the plates resulted in parts that didn't match up well enough to create a consistent mitred edge... So this is another bit of the backpack I'll have to do more carefully this time.