An ILM R2 Story

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Duncanator

Sr Member
Britain started going metric in 1965, but it was a slow process. Engineering for domestic stuff didn't really shift until years later. The Original Trilogy R2s were largely Imperial.

Which is, like, ironic. Doncha think?
(Face palm)
It took me a second, but that was great!
 

r2maker

Well-Known Member
RPF PREMIUM MEMBER
That drawing confirms a few things I noticed making mine - especially that the dimensions were imperial, not metric.

Of the top of my head I think the 80mm x 16mm shoulder bearing is the only thing on the ANH R2 props that is metric.
 

sapper36

Sr Member
RPF PREMIUM MEMBER
In my quest to make as many parts "accurately":unsure:, I was looking at the vents on R2. The variety of vents looks and materials was surprising.
The New Hope vents (pocket and underarm) were made from aluminum, of course. But Empire and later ones used vacuformed styrene vents.
(It's also possible that some may have had resin cast vents, but that is conjecture on my part.) I also looked around the 'net to see what the fan sites were making, but no one is making an accurate set of vents. So again I'm faced with the conundrum regarding "accuracy".

Initially my plan was to make my vents from styrene, but I was fortunate enough to have access to an original New Hope aluminum vent. My preference has been to steer toward the look of the New Hope R2s for mine. After studying it for some time, I decided I had to try to make mine using the same construction techniques as the original. After all - how hard could it be?!!

Well, it meant learning a new skill.:D

Yippee!!!

I love learning new skills!

A lot of R2 is built from folded and layered aluminum sheet, and the vents are an example of this. Each vent is made from 3 separate bent plates that have been brazed or welded together. The pocket is an additional folded piece.

Now my TIG welding skills are mediocre at best - not good enough to tack these thin plates together without blowing holes through them.
I've heard of folks who were so good that they could TIG weld soda cans, but that isn't me.

So I started looking in to aluminum brazing - My New Technique!!!
Brazing sort of falls in between soldering and welding. It works just below the melting point of the aluminum, so I wasn't gonna blast through the thin sheet material.

Behold! The fruits of my learnin'!

View attachment 1434793

The lower right vent is the original New Hope vent that I copied. You can see where it once had a switch and 2 LEDs installed in the pocket.
There is also a rough repair on its far right slot.

I'm pretty proud of these. I think I nailed my copies!
Any chance we could get a pic of these in construction or at least the back side? I'm not quite getting it - Neat work!
 

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Duncanator

Sr Member
Any chance we could get a pic of these in construction or at least the back side? I'm not quite getting it - Neat work!

As a matter of fact....

Here are some pics of my first attempt!

In the foreground are the parts that make up the vent. The top and bottom still need to be curved, but you can see how the parts go together.

19.10 Vents Parts 11.JPG


This shows the top pre-curved, and the next shows it post-curved.

19.10 Vents Parts 12.JPG


19.10 Vents Parts 13.JPG



....Aaaaand my first rough brazing attempts on the backside.

19.10 Vents Parts 14.JPG
 

Duncanator

Sr Member
The vent ready for the pocket to be installed

19.10 Vents parts 18.JPG


And more brazing on the backside.

19.10 Vents parts 20.JPG


It was a lot of fun trying out a new skill. I got better as I went, and learned (the hard way sometimes) how to work with it.

Building the vents this way gives them the proper radius on the edges of the recess. It makes me want to remake other parts of
my R2 using this method.
One other thing I haven't seen reproduced on other versions of the vents is the vent bars themselves. Everything I've seen has
bars with a rectangular cross section. The original bars are actually a trapezoid in cross section. You can kind of make out the angles
in this picture of my painted vent.

20.3 Vents Set 6.JPG
 

r2maker

Well-Known Member
RPF PREMIUM MEMBER
The original bars are actually a trapezoid in cross section. You can kind of make out the angles
in this picture of my painted vent.

Details like the sheet metal construction (vs milling) and the trapezoid shape are something that we’ve been trying to get traction on for over 15 years.

IMG_2252.jpg


It’s amazing to have someone who has had exposure to the original props confirming these build details. In the past the biggest challenge has been builders who have worked with folks that have had access to the original props challenging this kind of information.

It really looks like this is a body detail where the special sauce may have always been build it to the blueprint in sheet metal.

In the past the cost of milling and the volume required really made it hard to swim against the current. With online laser cutting being so affordable now and embracing methods like brazing, hopefully we will see a lot more people with the opportunity to explore the original construction.
 
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nkg

Sr Member
RPF PREMIUM MEMBER
One other thing I haven't seen reproduced on other versions of the vents is the vent bars themselves. Everything I've seen has
bars with a rectangular cross section. The original bars are actually a trapezoid in cross section.

That's awesome to see that confirmed! This is a detail visible in the cross-section ANH blueprint, including the section that Robert posted earlier to this thread - oh wait... the RPF is notifying me that he's just responded saying the same thing. :)
 

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Vagabond Elf

New Member
So, does the trapezoidal cross section imply the original vent lattice was built using cast bar stock? I know fairly little about metalworking, but I do know that the reason ingots have angled edges to to make it easier to remove from the mold.

It looks like the vent bars are also slightly proud of the frame?

Is there any specifics about the depth of the - is that a chamfer? The bit that one would remove from the rectangular cross section to make the trapezoidal. I'm doing a 3d printed R5-D4, and I'd like to try and modify the STLs for the vents.
 

nkg

Sr Member
RPF PREMIUM MEMBER
So, does the trapezoidal cross section imply the original vent lattice was built using cast bar stock? I know fairly little about metalworking, but I do know that the reason ingots have angled edges to to make it easier to remove from the mold.

No, it wasn't cast, and it wasn't bar stock. It was made the way Duncanator made it - sheet metal carefully folded over. Many of the metal details that people tend to make out of resin or CNC-machined metal were originally made from sheet metal in 1976.
 

joberg

Master Member
Very nice work indeed...and, as you said, for a first time (y) Interesting those vent bars. From pics you don`t really see those angles.
 

Vagabond Elf

New Member
No, it wasn't cast, and it wasn't bar stock. It was made the way Duncanator made it - sheet metal carefully folded over. Many of the metal details that people tend to make out of resin or CNC-machined metal were originally made from sheet metal in 1976.

Just so we're sure we're both talking about the same thing, I mean the bars in the middle of the vents, not the framework.

I know the picture I'm attaching is of Duncanator's build, but the edge I've highlighted below looks cut to me. If that's a bent-and-brazed end, I've run out of superlatives for what was already an amazing job!

Vents Question Pic.jpg


Or is this a place where Duncanator deviated from the original, and the original had a bent piece of sheet metal in that spot too?

Not trying to start an argument, just want to make sure we haven't gotten befuddled! And I'm trying to understand a thing I don't know enough about to ask the right questions. :)

Duncanator, earlier in the thread I posted about attaching pictures to threads in Astromech without using 3rd party hosts, but it looks like I was still too new and the post is hidden pending moderator approval. I'm only mentioning it here so you'll know it's coming!
 

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r2maker

Well-Known Member
RPF PREMIUM MEMBER
Is there any specifics about the depth of the - is that a chamfer?

This is where things normally get a bit interesting when measuring something off the end product with calipers, vs laser scanning, vs referencing the original blueprints.

With calipers, where do you accurately and repeatablely measure to determine the start and stop of a radius? Or to determine a theoretical interaction point?

With a 3D scan you can let the software put a best fit plane or cylinder through the surfaces to regenerate the theoretical intersects.

With the blueprints, the theoretical intersects are drawn in.

Ideally you would have the actual part in front of you, with a 3D scan on screen in the CAD, with the blueprints rolled out beside you.
 

Duncanator

Sr Member
Whew! Lots of discussion while I was away!

let’s see...

first off, the body of the vent is all bent sheet aluminum.
the bars however, are machined solid stock. I cut the angles on mine using a table saw. I could not say whether the original was done that way or milled, since any cutting marks had been sanded away.

The tops of the bars are flush with the top of the recess they are in. They appear proud of the surface because of the radiused edge of the recess.
 

r2maker

Well-Known Member
RPF PREMIUM MEMBER
I could not say whether the original was done that way or milled, since any cutting marks had been sanded away.

This is interesting question. I think Neil did almost all of the machined parts

This a photo of him fitting the original RC unit in 1976...

IMG_2262.JPG


He’s said he definitely was the guy doing all the cast work. He told us he cast the mechanical arms.

In the photo, we can see him in his shop with a body that was delivered to him from Peteric with no machined parts in it. The louvered intakes, the mechanical arms, the slot about the mech arms, the octagon ports, the vents ... almost anything with machining on the body is absent at this point.

Let me ask him if he did the castings and/or machining for the vents.
 

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