User avatar
By Petzrick
#4968342
For my next big task, I want to cut out the fiberglass N-filter, replace it with an aluminum one from GBFans, and install the Fincher e-cig vent kit. More on that later. Since I'll be working on the cyclotron, I also want to make some modifications to the cyclotron rings/holes. I think the four red cyclotron lights are probably the most iconic detail on the pack. They give the pack personality, almost like the way head lights can anthropomorphize a car.

But getting size and placement accurate is not easy. The Sony lobby pictures show some measurements with a tape measure, but they don't pinpoint exact values. I've read a few cryptic references to The Secret Proton Pack Plans, but the most common method is using the known scale of other objects to extrapolate values. This post by Wiz-GB008 is a good example.

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I had attempted this a few years ago, but was stumped by inconsistent results. A photograph's distance, angle, focal length, and lighting affect results. The image file's format, resolution, and compression can also complicate things. And when it comes to the cyclotron lights specifically, circular shapes are harder to compare, even without being partially obscured by the bumper.

My main reason for taking another stab at this is to figure out if those holes are crooked (the left-to-right alignment of holes compared to other horizontal "lines" on the pack such as the bottom edges of the EDA and gear box). They're slightly crooked on my GBFans shell, but they look straight to me in most of the reference photos. The camera angle and the bumper (which often is crooked) make it hard to tell. They do look crooked in photos of newer shells (not original but production-related) like the GB: Afterlife Phoebe hero pack and upcoming Mack's Factory idealized shell. But I'm hoping the original cyclotron holes are straight because it's cleaner looking.

Disclaimer/Spoiler/Warning: I haven't figured out any mind-blowing revelations. I've tried a few different approaches and figured out a plan for what I want to do with my own pack. None of this is confirmed, and I highly doubt that everything is dead-on. With any retro engineering like this, it's best to compare multiple results before using any measurements.

Problems
  • upper ring outer diameter
  • lower ring outer diameter
  • inner hole diameter
  • perfect or imperfect circular shapes?
  • ring/hole placement on cyclotron
  • alignment—Are they crooked?
  • placement of ring dimples
Assumptions
  • On the movie packs, the outside diameter of the rings should be consistent shell-to-shell, however, it's possible there may be some minor variation generation-to-generation. i.e. the recast of a hero pack to create a stunt pack
  • The hole diameter varies on different packs because these were cut after a shell was removed from the mold.
  • The center of the group of holes is not centered perfectly on the cyclotron. There is clearly more space above the top right corner of the top right ring compared to the opposite side.
  • The rings are 1/8" (0.125") thick. I'm not doing anything to confirm this because it's never seemed weird to me.

I was still scratching my head about what to try next until I saw photos of the Spengler GB2 semi-hero pack. These pictures are from the Sony Archives.

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This video has a lot of background on the Spengler semi-hero.



What caught my attention was this close-up that Demon Vice Commander posted on Lowberg's GB1 Pack Hero Build in a discussion on the ring dimples.

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A nearly straight-on photo with no bumper and decent resolution is a very significant reference. But what peaked my curiosity was the lower right ring and the space between it and the cast-in N-filter. It reminded me of my unused Venky shell (Diep variant). While not as pronounced on the semi-hero, the bottom edge of that ring seems misshapen on both shells, almost like adjustments were made to help fit the N-filter. The N-filter has been discussed in several posts (like this one by askernas) because its size complicates the ring measurements.

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The Venky shell, along with several other molds/shells out there, can be traced back to an original movie stunt mold (a cast of a modified production mold). But the lineage gets dubious. A few sordid generations the wrong way and you're Video Bob. This summary by Kingpin is a clear, concise history of the stunt shell and its bastard children.

Compared to the others (like this one), the Venky shell (including the Diep variant) is less generations removed from the stunt shell. However, it's not completely safe to use as a reference. On the stunt mold, components like the booster tube, ion arm, and HGA (and their surrounding areas) were filled-in. The mold was broken into four pieces, but it's not clear where the exact cuts were. The broken parts and filled-in areas were crudely repaired and recreated. The recasting process, shrinkage, and age of the mold have also affected quality.

The biggest problem is knowing which specific areas might still be accurate. The cyclotron is iffy. Something happened to the top right quadrant, creating the infamous egg shape. There's also less obvious warping diagonally opposite, which is easier to see if you look from the side. The discs (rings sans holes) are present in 1989 pictures of the first shell created from the repaired stunt mold (prior to fixing the filled-in areas). While these are admittedly old photos, I'm unable to see differences between the discs and those on my shell. I can somewhat make out the warped areas of the cyclotron. *These photos can't be posted due to ownership issues.

Originally, I decided not to trust the shell at all. But over time, as I've worked on modifying my GBFans shell, I have found the Venky helpful when making comparisons to other references. I've come to think of it as a soggy waffle. At one point, it was crisp but it's been left out too long and someone's eaten pieces of it.

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After seeing the similarity with the Spengler semi-hero, I decided to use a digital caliper to take detailed measurements. I immediately ran into a problem: imperfect circles. This could have been caused by a number of things after the stunt mold was discarded. It's also possible they weren't completely perfect to begin with. While it makes sense that washers or some sort of pre-fabricated discs were used for the original mold, these could have been custom made or even cut out by hand. There's a good discussion on this in this topic and this one, both by GhostGuy. Regardless of how they were made, common values (fractional or metric) also make sense from a design perspective.

I decided that scanning the shell would be more accurate. The warmer gray in the bottom right is the area I couldn't fit on the scanner because of the cast-in N-filter. Instead, I incorporated a photograph to approximate what was missing.

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This animation compares the Venky scan to the Spengler semi-hero photo, using a simple overlay and then an attempt to adjust for depth. Any similarities between the holes aren't relevant.

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The rings line up more than I expected but it isn't an exact match. On the Venky shell, the space between the bottom two rings is narrower. This may be partially because the center of the cyclotron sags quite a bit, more than other shells I've seen.

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Additionally, parts of the rings are shaped like muffin cups (top wider than bottom). I've seen similar on other shells, but it seems more pronounced on the Venky.

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Tracing over the scan, I put together this illustration to use as a 1:1 reference. The orientation is based on the left edge of the synchronous generator neck. On the shell, the top two rings line up horizontally very well. The right disc is slightly higher, but it's undetectable to the naked eye. There's more of a difference between the bottom two, but this would be difficult to see with the bumper attached. I'm pleased that the rings don't look crooked, but since this shell's forefather had been broken into pieces, it doesn't prove anything about the originals.


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Last edited by Petzrick on March 26th, 2022, 5:57 pm, edited 1 time in total.
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User avatar
By Petzrick
#4968344
Now that I had a new reference, I wanted to compare it to other data. The Sony lobby pictures that include a tape measure have been invaluable to this forum. However, when it comes to the cyclotron rings/holes, it doesn't seem possible to get exact measurements from the pictures. The tape measure isn't centered perfectly in any of the pictures. Instead of total diameters, only the holes and one side of the ring were measured (to multiply by two). This would only add up correctly if the hole was perfectly centered when it was cut out (which is doubtful). In the top right picture below, the tape end is angled away from the ring (towards the camera). In the same picture, it looks like the metal tip (which should be 1/16") is pushed in. It looks like it's pulled out in the top left photo, but it might just be loose in both. And on the bottom holes, there's no telling.

The values below show what it looks like to me, but this is doubtfully a complete set of accurate measurements. There are a lot of other readings on this forum, such as in this post by NotSabbat, who takes a different approach to figuring out the tape measure.

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My guess for the hole diameter was 1-3/8" which has been mentioned in a lot of other builds. I've also seen posts use 1-1/4" in reference to the ID of the Sony lobby hero pack. Since the tape measure pictures are of the semi-hero, I compared the hole shapes, using one photo of the hero pack and two of the semi-hero. The angle in these photos was minimal but I also made adjustments so that the photos could be overlaid using the outer diameters of the rings as a reference point (which assumes those are consistent).

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This animation shows the difference between the shapes.

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The two semi-hero sets of shapes (pink & green) look nearly the same, however, the hero shapes (yellow) appear to be a sliver bigger. By itself, this proves nothing. Even with adjustments, there's a lot that could throw off this test. I think it only entertains the possibility that the hero holes (on this specific pack) could be a tad bigger. Even if the same tool was used to cut the holes, just a little wiggle might cause slight differences. This could also be a discrepancy from using scale as a reference in different pictures.

My hope is that the Spengler semi-hero photograph will work better with scaling. To experiment, I tried using different values to resize the top right ring OD, and then updated the other three ring ODs accordingly. I then compared the results.

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My guesses for the Sony tape measure pictures don't work, unless you change the lower ring diameters to 2-3/8". None of the lower ring ODs seem significant because they are all close to common sizes. I. e. 2-1/3" (2.333"), 2-5/16" (2.3125"), 2-1/4" (2.25"), 2-2/10" (2.2"), 2-3/16" (2.1875") It does show that the lower left ring is slightly bigger than the right, like the Venky shell. The proportions from the Venky also scale well—if you base the scale on one measurement, the other values will also be close to the shell measurements (but not exact).

Next, I compared the Venky measurements with one of the pictures of the Sony lobby semi-hero. To begin, I traced the semi-hero and added measurements, based on 2.5" for the top right ring. The entire tracing was then reduced in size by 1% to closely match the Venky template. The measurements were updated.

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There's no way to know how close the measurements are. If anything, they seem more unusual. However, the overall proportions in the two sets of measurements appear to fit fairly well when overlaid, similar to the rough test with Spengler semi-hero. Although scale remains a challenge, the consistency between the three would be helpful with positioning the rings/holes and getting the overall look right.
Last edited by Petzrick on March 26th, 2022, 6:07 pm, edited 1 time in total.
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User avatar
By Petzrick
#4968345
At this point, I didn't have anything conclusive but was confident that I could at least get close. All of this might just be a glorified way to eyeball things, but I trust those eyeballs more than I did before. I put together a composite photo to expand the image I had of the Spengler semi-hero. There's still a slight angle and depth but the cyclotron is nearly straight-on. This time, I based my initial scale on the diameter of the Clippard valve. It's not the exact same height and is lower resolution than the cyclotron, but I was already planning on making additional scale adjustments later.

I still wasn't sure about the alignment (crookedness) of the holes. In the reference pictures, the left edge of the synchronous generator neck looks like it lines up with the vertical center of the pack and is perpendicular to some of the horizontal "lines" like the bottom gear box edge. In scratch-built shells (and likely the originals), the sync gen and upper part of the pack start as separate pieces which are then combined with a middle spacer. Depending on how they're put together, slight differences in sync gen orientation could account for crooked rings. By rotating the Spengler semi-hero photo, I'm hoping it straightens out those rings for my own piece of mind.

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To get more precise measurements, I used finer line weights and went over the tracing several times to distinguish edges from reflections and shadows. The tracing was then overlaid with the Venky shell template. Still not perfect, but slightly better than my rough tests. The semi-hero tracing needed to be scaled down slightly (close to 1% again).

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However, decreasing the scale would make the Clippard valve diameter too small (1.298").

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On my original tracing (before decreasing the scale), I had used white lines because they were easier to see on the photograph. If you change those lines to black…

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…it's easy to see that my circle was a sliver too small. If you look at the picture below (after the scale was decreased), resizing the circle to 1.311" doesn't seem correct either. 1.33" seems more accurate.

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But practically speaking, if you look at the small gap in the caliper below, that's the difference between 1.311" and 1.33". If you divide that into halves, it's less than my stroke weight. The bottom line is there's no way to be absolutely sure about any measurements unless you have a real pack.

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Once I was satisfied with the adjustments, I made an illustration to use as a template. *I'm intentionally not calling this a blueprint or pack plans. Although much is obscured in the composite photo, I included the sync gen and other components, by filling in the blanks using information from the Stefan plans, GBFans pack plans, and much more reference picture eyeballing. This also helped flatten out the depth of lower levels in the photograph. The illustration should be helpful with lining up the cyclotron's orientation, but my main reason for making this was to continue fine-tuning scale with comparisons to objects like the N-filter, ribbon cable clamp, and different sync gen magnets.

What I ended up with isn't an exact match with any other one set of values that I've seen, but it doesn't seem that far off either. The inner diameter of the holes (at least on the Spengler semi-hero) is close to 1-1/4". The top ring outer diameters are close to 2.5". However, like the Venky shell, the lower ring diameters are irregular and don't match left-to-right. I still think it's plausible that the bottom right ring was intentionally cut smaller or trimmed to help fit the N-filter. Using common fractions, the widest diameter from the lower rings would be less than than 2-5/16" and the narrowest would be greater than 2-1/4". Averaging all the lower ring diameters together would be closest to 2-5/16".


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I had a lot of fun doing this, but please take my results with a grain of salt. Or several. Take a look at how other builders approached this, especially those who have modified or made their own molds or scratch-built packs. Some great examples are Hijacker's What Was I Thinking? Build, mburkit's Hero Stantz Pack Build, Ppschrisbosh1's Proton Proton Pack Scratchbuild, and Larzl995's 'Idealized' Shell Build. There's also a good ring discussion in this post by abritinthebay, which gets into other broader aspects of retro-engineering, such as fractions vs. decimals.

I only did this for my own build, but the rabbit hole is bottomless. More references would help. So would having higher resolution in the Spengler semi-hero picture. Even without higher resolution, the picture might be adjusted more for angle and depth (preferably by someone with a stronger photography or engineering background). Although scale was not based purely on the Venky shell measurements, it might be worth doing another comparison after compensating for the dip and muffin rings. Or just wait for Mack's Factory.

My next step (before getting back to work on the actual pack) is tweaking the illustration to make an idealized version. Some things bother me too much, like the ring dimple placement and irregular circles. I'm only going to modify the rings/holes, so I may also need to adjust my template for the GBFans cyclotron, which has a slightly rounder outer edge.

And I didn't really forget but am just sad to say… It looks like those rings are in deed crooked.
Kingpin, tobycj, Q-man and 2 others liked this
User avatar
By pchrisbosh1
#4968385
Very cool illustration. The cyclotron rings are really wonky and uneven all around...I'm glad you were able to capture that with your drawings. I don't think there is a perfect circle anywhere on the hero packs. Even the Clippard spacer which we built as a perfect circle for so long is not so on the hero shells coming in at 3.25 tall and 3 1/8 wide not including the .125 frame around the spacer. Definitely some weird stuff going on with the hero shells and it makes it more weird when your trying to recapture those measurements and making since of the rest of the measurements around those areas. Great template sir and research! :cool:
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User avatar
By Petzrick
#4968401
Thanks, Chris. Your scratch build (and obsessive attention to detail) has been legend to me. It's bookmarked on my computer and phone. Hearing from you on this just made my day!

Very wonky. For the longest time, I chalked up ring oddities to photograph issues, until I saw the similarities repeat up close. Everything is just similar enough that you have to work against your brain to see it. Thanks for the tip on the Clippard spacer. Looking at different reference pictures again, it's harder to ignore how odd-looking it is. I just checked the Venky shell and it's definitely more of a diagonal oval than a circle. These are quick measurements with a caliper.

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The frame looks really inconsistent. Here's two pictures of opposite sides.

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This could be even worse on the Venky, especially since it's right next to the valley. I suspect that's one of the areas where the stunt mold was broken originally, going off of how narrow it got afterwards (and it just seems easier to cut there).

For this one though, I'm okay with leaving mine as a nice, non-accurate, symmetrically-pleasing circle. I think…
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By Brads_gimmick
#4969055
I havent been on here for a minute and I was so happy to stumble across your thread while doing some long overdue reaserch about Booster Frames !! Every twist and turn down a rabbit hole has kept me entertained for the last hour and bit. I cannot wait to see how far this goes!!
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User avatar
By Petzrick
#4969223
Thank you! I hope to have more posted not too long from (caught up with some deadline stuff). The booster frames are a deep rabbit hole all by themselves.
tobycj liked this

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