I'm wrapping up the Lineage Cast Project Run in the coming month, a project that has incredibly spirited away 5 years of my life, and while I'm working away on the final hilts, I figured I may as well get to what may be the final nail in the coffin for not just this project but my involvement in any more ANH stunt-cast shenanigans.
Now, for those that don't know,
vadermania had his production-made cast X-ray scanned by a process called XRF (Micro X-Ray Fluorescence Analysis) at the Natural History Museum in Berlin. There's more info here by
LOM in this post for further reading. From that process, it was deduced that the material composition of the cast was likely to be 4145/4145A, a type alloy for brazing wire.
As anyone following this project knows, halfway through my project run, vadermania provided me a 3D scan of his production-made cast to help with this passion project. I restored that scan back to the original wood buck's specifications and have since been working off of that pattern. While my current cast hilts are as close as possible to what was created then, I openly acknowledge what I offer isn't pinpoint accurate in size and material to the originals. While I make it work, and people seem to be generally happy with what I've done, what has eluded me thence was actually working on a cast that was made of the original material, and learning of all of the quirks and quibbles that it may entail. I've only ever worked off of suppositions and theories that my project has lead to regarding the
real things. That was, until tonight.
I've mentioned before in various posts that, after much searching and waiting, I managed to get a
very limited supply of 4145 brazing wire. Exactly 10lbs of the stuff, point of fact, and it was almost 1000 bucks shipped. The stuff isn't widely used anymore, as there are subsequently better materials made since 1975, and is heavily regulated due to its high silicon content. Silicon is poisonous when melted and its gasses are released. Well, just yesterday, the weather and winds were favorable; I donned by protective gear and fired up my forge for what feels like 5 years of tinkering has finally lead into being.
The first casts in near 50 years to be made from the original pattern
in the original metal alloy. These aren't just replicas
like the originals. These
are the casts that would've been used to make the Obi Stunt hilts.
There are no more variables for me to contend beyond my own inadequacies as a machinist. These are exactly as they were back in 1976. What I learn from these are now definitive statements and will no longer be conjecture as it has been my experience up until now.
I wish I could say that it was far-sightedness that I kept a hilt from my very first casting experiments with extruded aluminium stock, but it was, frankly, dumb luck that I've not melted it down or parted with it since those early days. It has provided me a control to compare my final casting-alu batch, and the dead-on, balls-accurate period casts to gauge their minute and not-so minute differences.
The first is immediately visual: the color and finish of the period alloy.
(the two on the left are made from casting aluminium alloy; the two on the right are the 4145 casts)
The surface finish on the cast-alu hilts is a glossier, warmer color with a larger "orange peel" surface texture. The patchwork crystal structure of the material is more visually evident on the cast-alu hilts, whereas the texture of the period casts (pictured in the middle below) is more like the extruded alu stock hilt; with a tighter, more compact structure, smaller "orange peel" texture, and cooler and lighter in color, but not as pale as the extruded-alu casts.
The second, is size: while not noticeable (especially in photos) as in person, the size of my period accurate casts strike that middle ground that I figured it might have between my admittedly larger cast-alu hilts, and to my much smaller extruded-alu hilts. I've admitted before that I purposely chose to go with casting aluminium for my project run because it doesn't shrink as much as the extruded aluminium, leading to a host of problems of proportion and sizing when machining hilts, and because it's not a dangerous to work with while maintaining good machining and detail capture (also, it's more affordable and readily available).
The problem, however, is ultimately the same as the extruded-alu casts: proportion and size. Casting alu, what I use currently, has a shrink rate of ~6-8 percent, whereas the extruded-alu casts had a shrink rate from ~11-14%. The period accurate material shrinks ~9-11% from the original negative.
I currently try to cut the minimum as I can away from my casting-alu hilts to retain its original detail as much as I can when it comes to making the kit offerings. Having learned from earlier attempts, better to leave more of what's there than of what can't be changed. I figure it's the lesser of evils.
That's not the case for the period accurate hilts, though. Everything is where it needs to be and there are no longer any vagaries to deal with when it comes to that cast. It makes machining it to match the reference material all the better (and easier) as scale and proportion is no longer a concern. I've already taken the cleaner of the two 4145 casts I have and have started machining it into a V2.
From my experiences with previous builds, I now know where to focus my efforts on first on this hilt and then work the proportions for the rest of the hilt on from there. On this, it is vitally important on getting the clamp section machined to match the tolerance of the clamp seen in the reference material. There isn't much space between the two clamp bars and they're parallel to one another, not bent inwards, so it gives me an idea on what I should be aiming to replicate on the period accurate cast.
What the ensuing machining revealed to me was both elating and depressing as it brought it full circle, back to when I first started this project, with my very first workable casts: my initial instincts were correct half a decade ago. I only now just have the evidence to prove it.
The V2 is a fully machined cast, they cut the entire surface down to get it nice and shiny on a lathe, the rounded undercuts are done with a round needle file and sandpaper. Because the proportions of the 4145 cast is correct, it scaled on the machined cast to the buck; something that's proved a bit of a bugaboo with me working with substitutes, taking either too much off or not enough. It proved that it there isn't too much taken off of the initial casts for the V2 (~.5-.6mm off the clamp section). They are both very similar in size and accounts for the similarities between the scaling of the V2 and V3. This also finally solved the issue with me in how much of the booster section was cleaned on the V2. The answer is: not completely! Because the cast lilts off-center by a few degrees, it just needs to be taken down to match the rest of "unclean" areas to create a semi-circular circumference. The rest is cleaned with a rasp and sandpaper. It isn't symmetrical by any means, but that finally solved for me just how much exactly needs to be done in that area.
The same was applicable to the windvane, another area that always puzzled me on its shapes. The odd angle and transition from the flare/lip into the windvane? The area initially with a groove from a light plunge cut? Initially cut down but mostly cleaned up with sandpaper and a round needle file. That's it.
As there is more to do with this, and as much as I wanted to keep on working, I had to leave it for tonight and this is where it is, at the moment. It also provides a pretty good sense of scale compared to the other hilts (L to R: casting-alu, 4145 cast, 4145 V2 WIP, extruded-alu cast).
One aspect that I'm looking forward to most is what this ultimately proves about the emitter. I've made no bones about my current emitters being too soft to bend without cracking or breaking trying to replicate the dents in the V2 emitter. The metal is just too soft with casting aluminium. Though I'm trying to hold back bias, if the emitter made of 4145 is similarly susceptible to unsuccessfully sustaining such serious, strenuous strikes, that most definitely proves that the V2's emitter was likely make of something else other than cast metal. That opens up another mystery box (which likely hides another mundane answer). That is something I'm seriously looking forward to test, while ultimately dreading having to buy another bar of rolled aluminium to machine a fresh V2 emitter from if my assumption is correct.
There's more to come yet, as the work beckons on the V2, and then the V3!