**Update**
Hi Everyone.
Exciting update, as there have been quite a few changes to the internals on the models! I was away last week on a camping trip, but I was busy having numerous discussions behind the scenes and researching various things from the "comfort" of my tent!
I've revised the models based on my findings, and I'm really happy with how things are looking...
The first and most obvious change is that the length of the motor chamber has increased dramatically. This is mostly down to me accounting for the length of the vintage motor, which was longer than more recent motors of the same/similar diameter.
I spent some time trying to track down the manufacturer of the gearbox and contacted a couple of UK based companies. Markel/Buhler don't appear to have manufactured their own gearboxes, so I figured the gearbox was probably supplied by a local (UK) engineering firm.
I was very excited to receive this reply from MFA COMO, who were manufacturing miniature gearboxes/reducers at the time of production:
"We did produce the 918D series which is 25mm in dia and we certainly have supplied the Elstree studios with items over the years."
After further conversation though, it turned out that the product in question was only ever sold as a single unit (including motor) and the gearbox would not have been sold separately.
I then contacted another UK based company who manufacture a similar standalone gearbox. The person I spoke to was very helpful, but they weren't able to give me any conclusive information due to restructuring within the company. Rotalink produce a gearbox that would have fit perfectly (being slightly smaller than the motor), but prior to 1986, Rotalink was called Sterling Instruments Limited, and there is VERY little information available regarding the products they offered.
It's "possible" that the planetary reducer gear that Rotalink make today was produced under their previous name, but due to a change in ownership in the early 2000's and then a change to digital record keeping, it's impossible to say for sure.
There is a New York based firm with the same name, who also manufactures gearboxes/reducers, but it seams that this is a coincidence and there is no connection other than them presumably associating themselves with the sterling engine.
So, whilst I was unable to find a conclusive manufacturer for the gearbox used in the original motorised stunt I think I've manged to get a good idea of the size it would likely have needed to be, based on the examples I've seen.
Accounting for the length of the motor (which is longer than more modern motors of the same diameter), along with the gearbox, the length of the mechanism chamber has been pushed further in to the grenade section of the hilt.
It also occurred to me that the step in the main bore wasn't necessary! I tried to find a bearing that matched the outside diameter of the motor as well as the inside diameter of the central rod, and I managed to find a flanged bearing that fit perfectly. It would have made no sense to add a step for the bearing when there was one available that fit the required measurements.
I've also added a bushing (plain bearing) to the neck section. At first I wasn't sure whether one would be needed, but having looked in to it further and having actually read up on Plain bearings and their uses, it now makes perfect sense! The purpose of a bearing is to reduce/eliminate friction between moving parts. A bearing at the neck would have prevented any friction between the rod and the body, as well as securing the emitter to the body section and keeping them both aligned. I looked in to various options, but finally settled on a straight bushing.
The quote from Brandon that
LOM and
v312 mentioned also got me thinking more on this:
The emitter neck fits cleanly into the neck of the hilt itself
This particular quote flew under my radar annoyingly, even after hunting down Brandon's messages on here. I think possibly because it was posted on a Vader thread.
I didn't want to add the bushing without looking for some visual evidence that it might be there. Luckily, I think I may have found some!
The last image here appears to show an exposed bushing. Having taken the image and done some comparative analysis in photoshop, the exposed neck section in this image is significantly thinner than the neck section of the hilt and emitter, and is thicker than the internal rod.
I've based my choice of bushing on the measurements taken from this image.
Another small update that you might notice is the the groove in the pommel for the set screw. I didn't want to add this feature without investigating for myself weather it would have been there. I thought that it was at least possible that there could have been a hole that the screw went in to rather than a groove. Having looked at all of the references, I have found that the pommel is NOT always oriented the same in relation to the body section, nor is the Glaflex clamp always at the same orientation, but this is to be expected I guess.
The fact that the pommel is orientated differently between references leads me to think that a groove might exist around the flange section of the pommel.
So, this is my latest cross section for the parts:
I really do feel, with each iteration, that we're getting closer to the truth of what the inside of this prop might have looked like!
As always, I welcome any comments/suggestions.
All the best and MTFBWY,
Dave