Just from the teaser pic, it looks to be shaping up as casting Alu. This is from the technical datasheet I have on the stuff I buy (a356 and a356.2), composition of casting aluminium is:
This along with the work BRRogers has done leads me to believe the making of these hilts weren't done by the guys at Elstree at all. This sounds more and more like the work the guys who made the parts for R2 had done. Could they have made the buck in-house since they may have had the Obi Hero on hand and had the hilts forged at a foundry somewhere else? Was it easy to get casting alu then?
I can’t necessarily remember my sculpture books’ details : (10 years+ Since I was in the program) but what I can generally say from what I understand is that some of the most effective product compositions that were older were also very noxious and would’ve almost certainly been regulated out of use in favor of new mixtures. Not to say that they were better- - but I’m sure old guys in the hobby /professions would say that some of what they used to use worked more efficiently than what is allowed today.
- not sure if that applies to any chemical or alloy composition for the aluminum castings specifically but I’m just saying that more to answer: what they had available back then had less regulation. Pros and cons to everything
That would make sense coming from a production sense. Especially if they did them well. I’m sure as you know Brian that sand casting anything with precision would inevitably create a symbiotic relationship for a production that was looking for bulk labor, and relatively high quality in a package deal. I bet the foundry enjoyed working on the parts (and having the unique work)
- not sure if that applies to any chemical or alloy composition for the aluminum castings specifically but I’m just saying that more to answer: what they had available back then had less regulation. Pros and cons to everything
I can believe that. Just from this site alone, with some folks in the movie industry, they've also gone on saying that some of the silicone they used to use lasted longer than the stuff today. Like you say, take it as you will. The composition I saw just rang a bell in my mind as I've seen those same elements in what I buy, maybe not to the same amounts but I just saw the connection.
I can believe that. Just from this site alone, with some folks in the movie industry, they've also gone on saying that some of the silicone they used to use lasted longer than the stuff today. Like you say, take it as you will. The composition I saw just rang a bell in my mind as I've seen those same elements in what I buy, maybe not to the same amounts but I just saw the connection.
Silica: In general… Is important in industrial product composition but is also the ‘big bad’ that causes systemic organ issues through fume, dust, inhalation or absorption (cancer). That’s one of the big ones now with regulation on percentages used in product: especially those that could potentially BE inhaled absorbed or injested
(Edit: sorry it’s cancer not Alzheimer’s… forgetful me hah)
I know I got a lot of people to reply to, I’ll get to that in the coming days! Sorry for being so quiet, I've been really swamped. But this discussion has gotten quite interesting, and with the number of pokes I’ve gotten at this point I figure I should take a little bit to respond now.
Two things first:
Wow, it's really nice to see the Wired stunt in more pictures! And I am pretty confident that it was cast off the V3, it's just very squished which makes overlays hard but if I recall the pommel cubes more or less line up.
And I think Bryan hit the nail on the head of all this with the duplicator and the wooden buck! Bravo on that. That was so exciting to see!
Well, the Sterlings were already premade by Bapty right? Because of the use on other films? The R2 parts I strongly believe were the influence on getting these hilts cast in some kind of metal, probably because of the shared technicians on both projects.
Dimensionally, that would indicate to me that the shrinkage wasn’t majorly significant with the metal casting… just that the buck was longer than the final stunt assemblies
THIS is what I've hinted at in a couple of posts. Cast aluminum shrinks quite a bit based on the research done by PPP, so I've been scratching my head at this for a while. Time for a bit of my own "weird wooden buck/casting theory" then...
So, taking a few steps back. I was fortunate enough to receive a few measurements off the original wooden buck, and to my surprise I found the buck today is actually a tad smaller than the blank metal casts when comparing my measurements in certain areas. Based on the numbers I had, it seemed to me the measurements were 1-4% larger on the casts than the buck... However some areas, particularly the booster, did show signs of shrinkage when comparing the blanks to the buck. This led me down a bit of a crazy rabbit hole and I had thought I hit the jackpot with the discovery of high-Bismuth content (55%+) based casting metals which actually do expand on cooling... by approximately 3%. Which was surprisingly the right percentage expansion needed depending on the type. However the downside to this was that Bismuth based metals are fairly brittle, and considering the abuse the hilts went through, I wasn’t sure that it would hold up. But I did find a few others agreed with my suspicion that it wasn’t aluminum - but we had no legitimate evidence one way or another. Because what I found was there was no actual primary source from the era saying these hilts were actually aluminum, and they have been substantially less researched compared to something like the R2 cast aluminum bits.
Here’s a quote (all be it slightly paraphrased and trimmed) from someone who handled the V3 in the Archives and spent some quality time with it that got my mind rolling about casting methods:
I thought foil was applied to the neck [of the V3] ... However, it felt quite solid, so it may have been cast that roughly from a degrading rubber tool? I used to cast white metal figures and they could tear up a vulcanized rubber mold and get rougher and rougher …
White metal and aluminum aren’t heavy when cast and could feel similar. It could have been pewter… The body felt hollow cast* which made me think vulcanized rubber molds...
It could have been molded in plaster through that wouldn’t give you an easily repeatable process whereas vulcanized rubber would. That is just my conjecture from experience...
The V3 was definitely rough in areas of its casting but I felt the roughness came from the grain of the wooden master being reproduced in the molding process.
I was thinking plaster molds for a long time, as I know Stears' SPFX team made plaster molds for a couple items (Like the original Dianoga if I recall), but RTV rubber was something I hadn't considered and seemed to make a lot of sense. Additional credence was lent to this theory by the rubber DH-17 mold made for ANH and owned by Gus Lopez:
A similar mold being constructed for the Obi stunts seemed reasonable to me, and something like this could easily slip and create the seam lines we see on the V3. Also the buck is coated in two layers of paint - white primer(?) and a black top coat. You'd really only need to paint a buck if you were casting it in a liquid like plaster or rubber. Basically, I thought I cracked it but I had zero evidence besides a bunch of a bunch of loosely connected bits, but I wanted to prove it before posting about it. (Spoiler alert: I was very wrong about the metal.)
Somewhere in the V2 thread I think it was, someone said something along the lines of "short of a metallurgical analysis or x-ray, we might never know" the composition of the V2 regarding if it was cast or machined. Obviously the V3 is probably even less of a realistic target for analysis. Then it got me thinking, well... there are two blank casts in private collections that could be analyzed... and I am very fortunate to know a guy that has one of them!
I think I was kind of half-serious when I suggested it, but then Tom actually gave me the greenlight to figure this out, and I was so darn excited. But for real, I can't thank him enough for his generosity and willingness to get it analyzed and taking the time out of his day to do it, I sincerely appreciate it, and I am sure others here are too, so I'll say it again, thank you so much Tom!!! We all owe you a great debt of gratitude for this!
I researched some ways to get the chemical composition of things analyzed, and I realized you have to be pretty particular about the methods being non-intrusive and non-destructive lol. Apparently a lot of the common methods for analyzing involves a lot of crushing and pulverizing... and I have a feeling that wouldn't have gone over well with anyone. Anyways, there is this technology/technique known as XRF analysis, or Micro X-Ray Fluorescence Analysis using an XRF spectrometer and by its nature it is non destructive and basically was all around the best bet to show chemical composition of something like this. The second step was to find someplace local - and the Museum für Naturkunde fortunately wasn't too out of the way (Thanks Tom!!). And shoutout to all the staff there as well, they were all so helpful and awesome, and without them this wouldn't have happened of course.
This all happened a little bit ago, and then I kind of fell of the face of the planet for a bit... So this was meant to have it's own thread but with the discussion going on in here, it is probably best suited to post here.
First, some lovely pictures provided (note these images have been upscaled I believe? At least that is what it sounded like on the notes regarding them.)
Here's the main event - the data:
As measured
Spectrum
O
Al
Si
S
Ti
Cr
Mn
Fe
Ni
Cu
Zn
As
Sum
Light_Saber_ 04.spx
2.21
82.25
9.82
0.04
0.02
0.04
0.19
0.38
0.11
2.64
0.44
0.02
98.16
Light_Saber_ 05.spx
3.97
80.91
7.69
0.03
0.04
0.05
0.37
0.99
0.12
2.66
0.39
0.01
97.23
Light_Saber_ 06.spx
4.43
79.07
8.96
0.01
0.03
0.10
1.01
1.76
0.10
2.62
0.41
0.01
98.50
Light_Saber_ 07.spx
6.39
82.22
9.92
0.06
0.05
0.02
0.08
0.13
0.16
3.16
0.42
0.01
102.64
Light_Saber_ 08.spx
3.44
86.84
5.30
0.04
0.03
0.06
0.29
0.77
0.13
2.64
0.40
0.12
100.05
Light_Saber_ 09.spx
4.41
83.27
7.10
0.05
0.03
0.05
0.26
0.90
0.15
3.07
0.43
0.13
99.83
Light_Saber_ 1.spx
3.34
81.46
9.81
0.06
0.03
0.03
0.14
0.45
0.13
2.94
0.41
0.01
98.79
Light_Saber_ 3.spx
4.08
83.95
7.03
0.06
0.03
0.03
0.18
0.62
0.15
3.21
0.42
0.01
99.77
Average
4.03
82.49
8.20
0.04
0.03
0.05
0.32
0.75
0.13
2.87
0.42
0.04
99.37
Standard Deviation
1.20
2.30
1.69
0.02
0.01
0.03
0.30
0.50
0.02
0.26
0.02
0.05
1.63
Normalized to 100% without oxygen
Spectrum
Al
Si
S
Ti
Cr
Mn
Fe
Ni
Cu
Zn
As
Sum
Light_Saber_ 04.spx
85.47
10.39
0.04
0.03
0.04
0.20
0.41
0.12
2.81
0.47
0.02
100.00
Light_Saber_ 05.spx
86.33
8.47
0.03
0.04
0.06
0.41
1.09
0.13
2.97
0.44
0.01
100.00
Light_Saber_ 06.spx
83.53
9.78
0.01
0.03
0.11
1.12
1.94
0.11
2.91
0.45
0.01
100.00
Light_Saber_ 07.spx
84.73
10.74
0.07
0.06
0.02
0.09
0.15
0.18
3.49
0.47
0.02
100.00
Light_Saber_ 08.spx
89.58
5.62
0.04
0.04
0.06
0.31
0.82
0.14
2.83
0.43
0.13
100.00
Light_Saber_ 09.spx
86.82
7.65
0.06
0.03
0.05
0.29
0.98
0.16
3.36
0.47
0.14
100.00
Light_Saber_ 1.spx
84.96
10.51
0.06
0.03
0.03
0.15
0.48
0.14
3.18
0.45
0.01
100.00
Light_Saber_ 3.spx
87.32
7.55
0.06
0.03
0.03
0.20
0.68
0.16
3.49
0.46
0.01
100.00
Average
86.09
8.84
0.05
0.03
0.05
0.35
0.82
0.14
3.13
0.45
0.05
100.00
Standard Deviation
1.87
1.82
0.02
0.01
0.03
0.33
0.55
0.02
0.29
0.01
0.06
0.00
Here's the write up provided by Dr. Hamann, one of the people who helped make this happen, regarding this:
The data in the table are given in percent by mass; Above as measured including oxygen from a possible thin oxidation layer and below without oxygen and standardized to 100%. You can compare the values below with values from known aluminum alloys and should thus come to an alloy type. A quick Google search yielded the tables, which are also in the appendix, in which the compositions of some aluminum alloys are summarized. Alloys containing Si can be found on pages 5 and 6. The measured values fit very well with the type 4145 or 4145A, which apparently have been in use since the 60s or 70s.
So, based on all that, aluminum alloy 4145 or 4145A is likely the best bet of the original metal of Tom's cast! I find 4145A to be especially intriguing because it was a material registered in the UK in 1976... Almost too perfect, eh?
In my opinion, there are still some prevailing questions to consider before putting this to rest however... All of the original cast lightsabers have various levels of patina and oxidation on them - are they all the same material? Obviously of the 4 castings, some of them have been altered through the years by being painted, sanded, repainted, and refinished.. But no two of their finishes look all that alike to me. If these were cast by production - I could see them swapping metal to whatever alloy was available to them from what they could scrape up for each casting.
Also, perhaps there was a foundry local to production (I looked into a few that were close to Elstree and in business long enough that they could have supplied it...) But I still don't think the castings are up to snuff for professionals to have done them. Considering the R2 parts were likely held to close tolerances by the engineers, the wonkiness of the casts and primarily the seamlines on the V3 really do not strike me as pro-jobs. Perhaps it could've been something fun for a foundry to work on because of the novelty as Bryan said, maybe it could've been done on the cheap since production was broke and the stunt sabers really seemed kind of last minute.
The biggest thing however, is my question about shrinkage is still unanswered. The Hero and the Buck are the same size, that has basically been proven now here based on all the work Bryan has done. But the fact that the metal casts are basically the same size as the Hero as proven here. I feel there is definitely some missing step in the casting process that we don't know about, for what it's worth.
Hope that was worth the wait, sorry for the delay in getting this out there!
I just wanted to add that it was a great day with the scientists at the museum. They showed me their huge collection of meteorites, which was absolutely impressive. I on the other hand tought them the basics of STW lightsabers, and they had a lot of fun wielding and filming my motorized Obi saber in the hallway.
I always wondered if the buck hadn't shrunk itself over the course of 40 years, and if that wasn't the reason. My early buck copies were straight from the Ebay photos and when the casts made of them compared to the one in vadermania possession, I thought it was due to just my casts shrinking and I finagled what would be my current buck to produce a closer match to his cast(s). It turned out this alteration also wound up making my buck match my Obi Hero replica of all things (something I didn't check before until BRRogers did it with his MK1).
I guess my bar of a365 is now useless. Time to find some 4145.
Depending on what wood it is, it would change size with climate fairly easy. The paint/stain prevents this alittle. But it would still continue to change size seasonally.. worse if this was kept in a non climate controlled area like a basement, attic or garage..
My life revolves around wood. And I’ve been lucky enough to work with all kinds from common pine, to right now ipe
Believe it or not wood can change drastically and very quickly..
The original buck doesn’t show any signs of cracks, which also made me curious judging by its age..
My assumption was (back then) the buck was oak.. But learning about wood turning, oak is hard to turn and most turners would use softer pines.. but pine dents fairly easy and it doesn’t looks like there’s any damage on the pommel section.. figuring this thing has been banged around enough of its life that the emitter is chipped off..
But the wood doesn’t have a single crack in it.. hard woods tend to crack easier then soft woods.. if it were oak I’d imagine this sucker would have some cracks somewhere.
But pine is a great contender when it comes to not cracking..
I still have no idea what it was.. but now leaning towards a soft wood rather then hard like oak, maple or hickory.
I’m not a big sports fan but I thought baseball bats were made of hickory?
Quickly looking for 4145/4145a options online and it doesn't seem like something one readily and easily gets. 4145 weld rods are only so long (36" it looks like) and they are a little under 40 USD a pound. Weld wire for 4145 can come in 20lb spools but I'm having a hard time finding suppliers for it. The most readily available I can find is in 5lb spools and it's still 300 USD. Which, if I melt the whole spool down, may be enough for 1 hilt after I remove slag, maybe one and a half? This stuff isn't economical on a small scale and it's extremely hazardous with its high Si content.
Whoever made these had these on hand and in large amounts. It's got to have come from a pro-shop.
Actually… this may be an accidental note for questioning.
Rate of cooling could affect the *amount* of expansion or contraction after being poured in the mold. Depending on the time of year, (ambient air temperature) or the method used to quench for expedience sake (if they did). I know sand molds can’t be moved safely due to risk of failure after pouring but sometimes a batch that is cooling together will take longer to cool and could suffer less shrinkage? PoopaPapaPalps any experience regarding that?
Or, I wonder if an experienced shop would use a tempering oven (or similar) for cooldown if they knew it could prevent said shrinkage?
Conversely I know aluminum reacts differently to steel regarding hardening or annealing…. Would quenching it prevent more shrink?
Actually… this may be an accidental note for questioning.
Rate of cooling could affect the *amount* of expansion or contraction after being poured in the mold. Depending on the time of year, (ambient air temperature) or the method used to quench for expedience sake (if they did). I know sand molds can’t be moved safely due to risk of failure after pouring but sometimes a batch that is cooling together will take longer to cool and could suffer less shrinkage? PoopaPapaPalps any experience regarding that?
Or, I wonder if an experienced shop would use a tempering oven (or similar) for cooldown if they knew it could prevent said shrinkage?
Conversely I know aluminum reacts differently to steel regarding hardening or annealing…. Would quenching it prevent more shrink?
Where I live, it gets really humid and muggy during the summer and as a result, I tend to get more pockmarks in my casts because the water in the air gets trapped in the molds when I pour, creating steam, which creates the bubbles. The best casts I ever got was during the winter, when the air is really dry. I used to cast a lot of parts all at once in one mold, having a single feeder fill all the parts, and the most I noticed doing it like that was inconsistency of quality throughout various parts that I was casting, as air forced in and out to one area, get caught in others, and it would lead to impartial fillings or pockmarks in the casts. Shrinkage becomes really noticeable in comparing other casts and especially machining it down.
Casting aluminium can be tempered to make it harder but that really depends on the kind of aluminium alloy used, not all will take nor will all behave the same. In my experience--as well as talking to pros off-site--shrinkage is unavoidable. It's just a part of the process. You can mitigate how much it shrinks depending on the metal alloy used and its chemical composition. A356 is often the go-to standard casting aluminium as it's safe (low Si content and good fluidity), has good machinability, and has reasonably little shrinkage compared to other materials in its price range. I was using extruded early on and I was getting tons of shrinkage with that. I've not worked with using welding material before as a casting material but I would imagine there would be some shrinkage of some kind; how much I can't say. I can't say how much it would contract in comparison to other materials as I've never worked with it. At this point, I'm not sure if I'm wanting to even bother risking not just my wallet on getting enough to play with, but my health due to the Si content of welding wire and how much I need to melt down in one go. I wouldn't feel right asking anyone else to either.
When it comes to quenching, if you're quenching, that means you've de-molded while it's still hot, and quenching is affected by the temp and condition of the water in itself (if you're using water, too). Hard water over distilled, agitation and temperature; how long you quench, how fast you quench, all of that can lead of various outcomes. As an amateur, I wouldn't be able to tell you about it in detail. A professional would tell you the optimal conditions for it all but I can't. I can only tell you that I've not seen any real significant difference between quenching or not in terms of shrinking with alu-alloys. I have noticed that when I've quenched, the casting alu I use does get a bit harder but noticeably more brittle. Again, I don't know if it's my material or experience (or lack thereof), but considering my Al content has almost 10% more than what these original stunts were made from, you'll have to take that as you will. They very well may have done one or the other, or even both, or not at all. There is currently no evidence as to whether or not they quenched or annealed the casts afterwards (unless vadermania wants to have his cast sliced up to have us look at its grain structure), and annealing depends a lot on the alloy itself--it may need quenching, it may not. As such, I've not tried to anneal any of my casts so far (although, just quickly Googling it, I could try it).
My question regarding these, as with all Star Wars stuff made for production: would they have bothered going the extra step? I believe they may have quenched these, but I don't know about much else after.
