Union Pacific Big Boy in 3/4 Inch Scale

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Pontiacguy1
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by Pontiacguy1 » Sat Jan 13, 2018 2:41 pm

Maybe some were coal and some had been converted to oil fired?
Winter vs. Summer, dunno. Maybe air density?

Rwilliams
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by Rwilliams » Sat Jan 13, 2018 4:42 pm

Recent information has it that only one Big Boy was ever converted to oil firing and that was only for a short period of time for testing. Except for the testing time, no other Big Boy locomotives were ever converted to oil firing. The only other exception will soon be the 4014 when it operates again.

Too many details have been slowly lost to time as those who worked with big steam pass on. The massive cleansing of steam knowledge from company files at the end of steam did not help matters either. My father observed the company trash burner in the terminal where he worked filled with steam drawings and soon burned up as new diesels idled near by on the shop tracks.

JJG Koopmans
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by JJG Koopmans » Sun Jan 14, 2018 8:03 am

@Rwilliams,
Thanks for the orifice data!
kind regards
Jos Koopmans

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Fri Mar 02, 2018 10:25 pm

Hi,

After the boiler pressure test milestone was successfully completed, I started working on the boiler cladding. I had made the front portion from .032" thick (1/32") brass sheet several years before, but I still had to silver solder tabs for 10-24 soc. hd. capscrews at the front, in the middle and at the back so the cladding would be tight on the boiler itself. It also had to be properly fitted to the dome and safety valves. I also made the cladding thick enough that I could tap it for screws (#0-80). If necessary, I can drill holes in the cladding and soft solder threaded bushings in place for heavier connections like the catwalks and maybe even the handrails.
Boiler Cladding-1a.jpg
Cladding starting at front of boiler. You can see the 1/8" dia boiler pressure sensing tube at the front of the cladding
As you can see in the pictures, the front cladding sleeve goes back to the front of the firebox and then a second formed sheet extends to the front of the cab. In the pictures, the back portion still requires some more fitting to be done. I will use brass angle to fasten it to the front of the cab.
Boiler Cladding-2a.jpg
Cladding further back on the side of the boiler
If you look closely, you can just see the #0-80 screws that hold the dome cover in place; the sand domes and the dome in front of the cab still must be bolted down with the same screws.

Before I can fasten the cab on permanently, I have to install the insulating brick holder (you can see this in previous pages of this thread) and the stainless steel excess air shield (still to be made) in the bottom of the firebox.

I haven't decided if I will make the cab roof removable for running (it bolts on), or do something different like a hinge at the front. Any suggestions?

Richard Trounce.
Last edited by RET on Fri Mar 02, 2018 10:43 pm, edited 2 times in total.

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Fri Mar 02, 2018 10:37 pm

Hi,

Here are the final two pictures.
Boiler Cladding-3a.jpg
Cladding at the rear where it joins the cab.
As you can see, the domes are painted "court grey" which is the same colour as Gerhardt painted the chassis. I intend to paint the cladding and the cab this same colour, but I will probably leave the smoke box in its unpainted condition. I think that will look OK since it is made from copper.
Boiler Cladding-4a.jpg
Another view of the cab area.
While its not prototypical, I think that painting this model in black would make all the detail harder to see, so that's why the grey colour. Gerhardt did a great job in building this model so I would like his work to be visible. As you can see, a little more fitting and trimming is required on the back portion of the cladding.

Richard Trounce.

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Fri Mar 02, 2018 11:04 pm

Hi,

Just a fast addition. While Gerhardt put six safety valve bushings in the boiler he built, the real Big Boys only had five, so that's why one of the boiler bushings is blocked off (visible in picture #2). The plugged one is in the location that's missing in full size. Five safety valves are probably quite a bit more than is required for a model, but you might as well "get it right" when you can.

In the second picture you can also see one of the blowdown valves at the front of the firebox.

Richard Trounce.

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Carrdo
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by Carrdo » Sat Mar 03, 2018 10:17 am

Nice job Richard.

Don
(from somewhere in Europe).

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Sat Apr 14, 2018 12:54 pm

Hi,

Some more progress on Big Boy. From something I saw on line, apparently 4005 was the only Big Boy that was wrecked. By mistake, someone threw a switch into a siding causing 4005 to derail and roll over. Just a bit of trivia that hasn't got lost yet.

Since the last pictures, as you can see, I have finished and permanently installed the stainless insulating brick holder assembly. I have to do that before I can mount the boiler on the chassis because it isn't accessible after the boiler is mounted.
insulating brick and box holder(a).jpg
box holder - right side up
shield (fastened to underside of box hoder)(a).jpg
mounted in position in firebox
The shield prevents too much excess air coming into the firebox and cooling the flue gasses.

Richard Trounce.

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Sat Apr 14, 2018 1:14 pm

Hi,

Here are some more pictures showing the boiler cladding in place. The front wrapping is permanently installed together with the dome cover. The front sand dome is in position but the #0-80 bolts that hold it aren't in place yet.

At the start of the cladding, you can see the 1/8" tubing for the boiler pressure sensing line from the throttle venturi that goes back to the propane control valve. The line will run just under the catwalk, which like the hand rail, isn't there yet. The propane automatic pressure control valve will be mounted under the cab. That's another thing I still have to finish designing and make.
start of cladding(a).jpg
Beginning of cladding - permanently mounted and painted.
Under the front sand dome will be the top feed check valve assembly. I know how it will work, I just have to finish designing and building it. If you look carefully, you can see where I have bulged out the cladding slightly so I can run the top feed supply line out of sight until it too runs under the catwalk.
further along cladding(a).jpg
This shows the five safety valves including the blanked off sixth valve location.
Richard Trounce.

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Sat Apr 14, 2018 1:22 pm

Hi,

Here are two more pictures showing the cladding as far back as the cab. The first shows the second sand dome, the dome in front of the cab, and the front of the cab.
still further along(a).jpg
This shows the second sand dome.
The second shows the dome in front of the cab and the cab itself. Gerhardt made the cab and the domes, I am just carrying on with the excellent work that he started.
back of cladding(a).jpg
rear dome and cab
I still have to paint the inside of the cab and reinstall the handrail in the roof.

Just the next step in a long road, but we're slowly getting there.

Richard Trounce.

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Sun Apr 15, 2018 9:16 am

Hi,

After I posted the last four pictures, I noticed there was a horizontal yellowish band along the side of the boiler. There really is nothing there, its just a reflection on the paint of the yellow lift table the engine and stand sit on.

Its a long, slow road and there is still a lot left to do, but its encouraging when the engine begins to look the way it should. The smoke box still has to go in place and that will help the locomotive's appearance a lot, but that's still down the road a piece.

I once said that after the pressure test, it was all down hill from there and yes, that's true, but its still a long hill!

Richard Trounce.

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