1:100 Zaku Kai (ザク改) - Head Construction
The design of the head was always a bit vague in my early design drawings. Details like how wide the eye visor was, the curvature and overall shape of the head, and how far down the snout extended were left unresolved for long periods of time. In later design drafts I started to resolve some of these details and cooked up the first version of the head design, drawn at double-size (relative to the 1:100 part that would later be constructed) for better detail.
A few aspects of the design were established pretty early on from my reactions to other builds, as well as impressions taken from the anime and lineart - the head is fairly skinny and long, more or less egg-shaped, and significantly smaller overall than the head of the original Zaku. It was also my impression that the chest block was divided into more or less equal thirds, and that the head was about the same width as the middle part of the chest. This led to an estimated head width of 17-18mm in the original plans. There was a considerable negative reaction to this decision when the plans were posted online, but I have been and continue to be quite sure that I made the right choice.
Several years ago, when I was just getting started as a Gundam modeler, I had a chance to read one of the Suku Suku Scratch articles in which Misaki Mitsuaki built the Zaku Kai. One of the things that really impressed me was how the modeler was able to build the same part, several times, using several different techniques, and all the results would match. (Pretty well, anyway...) The head was shown built by gluing a bunch of sheets of styrene together into a block and carving the shape, by creating a crude form out of poly putty and carving that, and by creating the basic form from foam and hand-forming a rolled-out sheet of epoxy putty over it. I think the epoxy putty method was probably the most graceful, but I decided to go with a method that was shown for making the legs: assembling cross-section templates together, filling in the hollow interior with clay, and creating an epoxy putty shell.
Earlier this week I created "Head Ortho Rough #2", another 1:50 scale drawing of the Zaku Kai head, which would actually be the one I'd build from. I drew in 1:50 scale to improve the precision of the drawing: to further improve its precision, I scaled it down and mirror-imaged it on the computer, then continued the work with the printout. The printouts were spray-glued to styrene sheet, cut out, and assembled together. Most of the empty space was filled in with clay, and then the outer shell of the head was formed by adding poly putty. The process is very much an iterative one: the smooth curve is formed by adding poly putty, then carving it off again. In the later stages of work the process will be further refined with the use of finer poly putty and measurement of the curves of the part.
Pressing onward: I drew out the bottom-view of the head so I could create a styrene template from it and glue it to the bottom of the head work-in-progress. This makes it easier to establish the contour and edge of the bottom of the head and also to create the snout (and to ensure that it's reasonably well-centered, too). I then used more poly putty to fill in the contours, both for the head and the snout. At this point I decided that I'd gone as far as I could usefully go with Bondo, so I switched to Mori Mori. I can't find my Mori Mori catalyst at the moment so I used Doro Doro catalyst (I have plenty of that since every time I buy a can of Doro Doro it goes bad before I use it all up...) So far it hasn't hardened up fully, but I expect it will in a few hours. Just for kicks, I included an old, modified 1:144 Zaku Kai head that I made about four or five years ago in the picture - comparison, if you like.
Since the last update, the head has been through a few stages of refinement, in which the head was bulked up with poly putty and sanded down again. The head still needs work (in particular, I think the back end of it is a bit lopsided) but I am hoping a couple more refinement passes will smooth that out.
After earlier work I decided that the snout of the head part looked crooked. To solve the problem I split the head in half down the middle, to make it easier to take measurements relative to the center line. This was relatively easy because the part was built with a thin styrene plate on the center line. From there I improved the part a bit: it's shaping up but I need to work out a way to effectively check the two sides against each other.