Any drawings for 2.5" scale Mallet Moguls out there?

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NP317
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by NP317 »

Pontiacguy1 wrote: Wed Feb 09, 2022 10:21 am LGB made a Uintah 2-6-6-2 mallet for a while: https://www.trains.com/grw/news-reviews ... ocomotive/
Actually a simple articulated, not a Mallet. Certainly a good choice for you to model.
And the locomotive I saw at Train Mountain may have been modeled from that prototype.
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Berkman
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by Berkman »

I can't see any advantages to a compound in 2.5 scale. The firebox looks quite large and you should be able to make enough steam for 4x simple cylinders. This would be quite the project, probably more complicated than building one of Roger's 4-6-6-4s since so much design work and potentially patterns/castings would need to be made.
malletmogul
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by malletmogul »

The plan would be to mostly build it up from bar stock except for the saddle, cylinders, and driver centers. Using off the shelf materials where reasonable. I haven't decided on a final scale or simple/compound or soak/superheat or even gauge yet, the hope was to see the drawings of others that had been built before. The only thing I do know is I want it to be oil fired, and have saddle tanks with an optional tender like the Rayonier 111, but not necessarily modeled after any specific prototype.
Pontiacguy1
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by Pontiacguy1 »

Have you ever built/fabricated anything like this before? What type of skills and equipment do you have? People on here can better advise you if they know what your capabilities are now, rather than guessing. The locomotive you are wanting to build is going to be very complex and take a much longer time than building something that is an already established design that you can easily get castings and parts for. In 2 1/2" scale, building a 2-6-6-2 simple articulated locomotive, is probably going to be a 4,000 to 5,000 hour project, especially since scale drawings don't currently exist and you probably can't get castings off the shelf somewhere that will work either. You may know this and be OK with it, but a lot of people don't know how big of a project this can be.
malletmogul
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by malletmogul »

I understand the scale of the project and I am OK with it. I am a machinist by trade so I don't have much trouble wrapping my head around the labor involved. I have at my disposal a big LeBlond lathe, as well as a Bridgeport, CNC mill and lathe, and a wire and sinker EDM. Since 2.5" scale is mostly uncharted territory, I am leaning towards 1.5" scale at the moment to get started, since then I could use more off the shelf parts and learn how to build a locomotive. Once that one is done I can move onwards and upwards to something bigger. With my skills and tapping the experience of other builders, the complexity of the project does not daunt me.
Berkman
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by Berkman »

The size and weight of a 2.5 scale 2-6-6-2 would also be something like maybe 3,000-3500 lbs and would be quite the beast to transport etc.

You could use off the shelf castings and build a 1.5 scale 2-6-6-2.

Little engines modern 2-6-0/0-6-0 castings, or Roger Goldmann 2-8-0 castings would provide "off the shelf" cylinder, valve gear, drive wheel, and other castings. You could also use these drawings as a starting point for the frame modification needed. But most of the brake rigging, rods, suspension etc would match the LE or RG design. I think this would be much more approachable. Or Roger Goldmann also offers a complete 4-6-6-4 castings/drawing kit, but it's like 25-30K just for the drawings and rough castings, plus I'm not sure if his parts are still available.
Pontiacguy1
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by Pontiacguy1 »

Based on your response, then I'd say you are well-equipped to handle a project like this. It's still a super large project with a whole lot of R&D that will have to take place for you to be able to make a successful working model. That said, the advice to go to 1 1/2" scale will probably be good, unless you want to make patterns and have castings poured. The locomotive will still be large and powerful, but hopefully easier to store and transport. You will also have a lot more currently available stuff that could be used or adapted to your 2-6-6-2, like Berkman said above.

There is a 2-6-6-2 that was built in 1 1/2" scale, 7 1/2" gauge back about 20 something years ago. I do believe this one was a mallet. It may have just been built to look like a mallet with two sets of simple cylinders, I don't know. That might be somewhere to start.

Check this thread: http://www.chaski.org/homemachinist/vie ... 8&t=108365
malletmogul
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by malletmogul »

Good feedback, thanks. I have seen that picture of the Great Northern 2-6-6-2. I was thinking of adapting the LE ALCO parts since I would like something with a bit more swept volume. My initial plan would be to build it from the bottom up, with the boiler last in case it proved to be too much of a project, that way I could decide to break it up into a Mogul or Prarie or something before pulling the trigger on the boiler. That decision would be years away even if I were to start building today. So far all I have done is some CAD modeling and a whole lot of reading.
Berkman
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by Berkman »

the LE alco northern has 10 inch drivers, a scale 80 inches. Most standard gauge 2-6-6-2s had 57 inch drivers -which would be around 7 inches like the LE modern mogul or RG 2-8-0 parts. About the largest drivers on an articulated were the N&W A's at 70 inches.

Your frame design will change a lot if a mogul or a building a 2-6-6-2, this would be probably "the" critical design planning of the project if uses off the shelf 1.5 scale castings. I think you'd have to commit up front to the articulated.

The boiler of a 1.5 scale 2-6-6-2 will probably be smaller than a LE alco northern boiler.
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Bill Shields
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by Bill Shields »

and this will be your FIRST loco?
Too many things going on to bother listing them.
Berkman
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by Berkman »

I'm with Bill, maybe build a stock LE 0-6-0 or something then start on the 2-6-6-2
malletmogul
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Re: Any drawings for 2.5" scale Mallet Moguls out there?

Post by malletmogul »

I have considered that yes, however I do not have unlimited storage space or free time, so I would rather start on a longer project if it's something that really motivates me instead of something simpler. As I said, I am not looking to model it out of a specific prototype. It would be a sort of kitbash of things I like from various prototypes. I want it to be a strong and fun locomotive to run before above all else.

The idea RE: LE Alco cylinders would be to use smaller drivers.
Last edited by malletmogul on Thu Feb 10, 2022 7:11 pm, edited 3 times in total.
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