- March 26th, 2022, 5:14 pm#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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
- 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.
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.
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.
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.
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.
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.
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.
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.
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.
Last edited by Petzrick on March 26th, 2022, 5:57 pm, edited 1 time in total.
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