Big Boy in 2-1/2″ and O gauge

[Carl WalkerParticipant @carlwalker]

Hi all,

I am trying to find any info for designing a model of the Union Pacific Big Boy in either 2-1/2" gauge or O gauge (or possibly both). The idea being that I can tinker with, and gradually produce a set of construction drawings while I am working on building my current project, LBSC's Austere Ada.

I'm pretty much an armchair modeller, and have been reading model Engineer for over 20 years, and MEW for around 10 years, but I do like to work on designs for models, even if I never end up making them

I found a post that mentions an american company that produces original drawings of the full size loco, and plans to make a "Challenger" loco in 7-1/4 or 7-1/2 gauge, but the price they ask for a set of drawings is out of my range. I wondered if anyone knows of some model construction drawings for this or any similar loco – perhaps in 5" gauge – that I may get for a reasonable price. Alternatively, I was thinking of maybe drawings for an American 4-8-4 loco in 2-1/2" or 5" gauge, that I could use to see the methods of US style loco construction.

I do have a book, "The Mallet Locomotive" which gives some technical info and a line drawing of the Big Boy, from which I can get wheel diameters and spacing between wheels, plus cylinder sizes etc. but I really could do with more information about frame and chassis construction, plus more details of what all that pipework on the outside of the boiler is for, things like that.

Any help would be gratefully received,

Thanks

Ricky Walker

[Carl WalkerParticipant @carlwalker]

Looking for info to create design

[Carl WalkerParticipant @carlwalker]

Having had a good look at the options available, I have decided to save up for a set of the reproduction works drawings for the "Big Boy" available from Live Steam Locomotive Supplies in the US. Although expensive, there are 53 sheets of drawings in the set, so not so bad when you look at it that way. Then I can spned a happy couple of years creating model drawings from them

[macmarchParticipant @macmarch]

May I suggest either of these 2 books.

Big Boy by William W. Kratville 1972 ( no ISBN)

Train Shed Cyclopedia No 47 ISBN 0-912318-79-5

The first is a history of the class, the second has dimensioned drawings that may serve for your needs.

cheers

Ray

[Jim NolanParticipant @jimnolan76764]

The prints Roger Goldman sells are from the stuff Truson Buegel used to sell. Very limited and in my opinion not worth the money.

You need to go to the Union Pacific historical Society. They sell CD's of complete sets of works drawings for Big Boys and challengers for about $60. All in pdf and given an A0 drawing scanned in this country costs £10 plus they are giving them away. I have a set for the challenger and they are all very good quality scans.

The website's not that clear but go > company store>search, put in drawings and they all come up

**LINK**

Jim

[SteveIParticipant @stevei]

Hi,

I recently ordered the "4 set" of UP drawings.

http://shop.uphs.org/uphsst01.html

Please private message me.

Steve

[Carl WalkerParticipant @carlwalker]

Hi all, thanks for the replies.

Ray, I will certainly have a look for those books, will be usefull to have in my library

jeff, thanks for the info, and helping me avoid what could have been an expensive mistake, and thanks for the link. Those prices certainly look within my price range

And Steve, I have replied to your PM, makes more sense now I have read the messages since my last post

Thanks fro all the help.

cheers

Ricky

[Halton TankParticipant @haltontank]

Ricky, I sent you a PM regarding a source for the drawings of Big Boy.

Regards Luigi

[SteveIParticipant @stevei]

Ricky,

Please check your PM

By the way did anyone goto Ally Pally? There was a Big Boy chassis in 7.1/4 gauge on the stand of the Northolt Model Railway Club. I had an interesting chat with the builder.

Steve

[Carl WalkerParticipant @carlwalker]

HI all,

Well I have a set of works drawings now, and I have been having a good look. the main engine chassis (what is the plural for chassis?) seems to be a huge hollow steel casting on the original, and the drawing is so covered in dimension lines, hidden detail lines, etc, that it is difficult to make out the overall shape of it, but I'm getting there. I made a little start today, drawing the wheel layout of the O guage version, and immediately saw that there may be a problem with the driving wheel spacing. Since the flanges on a model are over scale, on the model at scale wheel spacing, there is just 1mm clearance between adjacent wheel flanges. I just have to decide whether to reduce the wheel dialmeters, or to increase the spacing between axle centres. All part of the fun of own design I'll post again when I have some more done.

Cheers

Ricky

[Another JohnSParticipant @anotherjohns]

Ricky;

You could always get the 3D model to get basic dimensions.

Makerbot contracted someone to draw and print one in 1:16 scale, available **LINK** on the net.

John.

[Neil WyattModerator @neilwyatt]

> chassis

Chasseurs?

Neil

[Carl WalkerParticipant @carlwalker]

Thanks for that link, John, I have downloaded the files, and will have a look later today. Should be very useful.

Neil, sounds about right, lol

Cheers

Ricky

[Carl WalkerParticipant @carlwalker]

Hi all,

I have been spending my time drawing up the driving wheels in both O and 2-1/2" guages for this loco (and learning how to use the CAD program I have, as well), and been thinking about how to cast the wheels.

I think, especially for the O guage wheels, that a lost wax, or investment, casting process would be suitable. I have been reading up about the process, and bought a book on the subject from Camden. However, most of what I have read deals with lower melting point metals such as aluminium and bronze, and uses plaster of paris as the "investment" or mould material. Obviously this would not be suitable for cast iron, so I need to find a source of investment material suitable for casting in cast iron.

Another option would be to maybe cast the wheels in aluminium or gunmetal and add tyres machined from steel, more like the prototype

Anyway, that is where I am so far, I have the machining drawings done for 2 of the 3 differeent driving wheels, and have drawn up casting patterns for cast iron wheels in 2-1/2" guage (although I still have to play around with the dimensions, trying to get them big enough to read, but not so big they overwhelm the drawing)

Cheers

Ricky

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