CPR G5C Class 1246 Pacific

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Harold_V
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Re: CPR G5C Class 1246 Pacific

Postby Harold_V » Sun Sep 24, 2017 1:10 am

thunderskunk wrote:I'm really good at starting projects that will never work, so bear with me. We're going to try a hydraulic press. Not a pump one for pushing bearings, but one powered by an HPU.

I expect that you'll experience rapid cooling of the object you hope to shape, due to the long cycle, but it's certainly worth a try. Just keep in mind, you want to keep the heat in the part, not the related working (shaping) pieces, which will deform if heated beyond a reasonable temperature, so limited contact is in your best interest. That's why hammers are used, as they strike and retract quickly.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

thunderskunk
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Re: CPR G5C Class 1246 Pacific

Postby thunderskunk » Mon Sep 25, 2017 9:17 pm

Harold_V wrote:I expect that you'll experience rapid cooling of the object you hope to shape, due to the long cycle, but it's certainly worth a try. Just keep in mind, you want to keep the heat in the part, not the related working (shaping) pieces, which will deform if heated beyond a reasonable temperature, so limited contact is in your best interest. That's why hammers are used, as they strike and retract quickly.

H


That's a good point. I've seen dies made a few ways. The rear wheel set has spokes (though impossible to see even on the prototype) which could be an opportunity to experiment without too much time wasted if it doesn't work. I'm going to start by machining the die as one piece. If it doesn't repeat to a reasonable tolerance, I might try replaceable inserts, which would locate similar to an indexing end mill. That would allow me to make the middle and outside drivers on the same fixture with different sized counter weights.

So.... I'm sifting through the drawings. I saw FLTenwheeler's J-class pictures of his castings for the crossties... wow. Makes me want to invest in 3D printing. I was just gonna mill blocks for crossties and bolt the frames together. Is that too simple to work?

How are crossties labeled? I just write them by what's mounted to them for now, but it'd be nice to know the right lingo.

Above each crosstie, I see a flat sheet which goes up to the boiler. Is this a support for the running boards and the mount is just hidden under the boiler jacket? I can't imagine such a thin sheet doing anything for supporting the boiler itself.

Sorry, lots of questions and not enough action.
Crosstie question photo.png
"We'll cross that bridge once we realize nobody ever built one."

Harold_V
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Re: CPR G5C Class 1246 Pacific

Postby Harold_V » Tue Sep 26, 2017 1:43 am

thunderskunk wrote:I'm going to start by machining the die as one piece. If it doesn't repeat to a reasonable tolerance, I might try replaceable inserts, which would locate similar to an indexing end mill. That would allow me to make the middle and outside drivers on the same fixture with different sized counter weights.

How much tonnage do you have at your disposal?

I was just gonna mill blocks for crossties and bolt the frames together. Is that too simple to work?

How are crossties labeled? I just write them by what's mounted to them for now, but it'd be nice to know the right lingo.

I'm afraid you're going to have to rely on others for these questions, as I am not familiar with the topic.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

Pontiacguy1
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Re: CPR G5C Class 1246 Pacific

Postby Pontiacguy1 » Tue Sep 26, 2017 7:28 am

I've got to ask a question... What is your real goal? Is your goal to try to do all this stuff differently and see what you can do with it, or is your goal to produce a working 1/8th scale steam locomotive as quickly as possible? I'm not trying to be a smart-butt or question your motives and methods, but it seems to me you are taking a very long and expensive route to get where you are wanting to go. If you like the build more than the finished product, then by all means 'forge' ahead. If your goal is to build a working locomotive in a reasonable amount of time and with as little hassle as possible, I'd say you're going in the wrong direction. There is a reason why nobody else does this type of thing in making a small scale locomotive: It takes a lot of time, the extra strength isn't needed, and once done and painted nobody can tell the difference anyway.

If you are determined to do it this way, then by all means go ahead and do it. Some people just love to do things differently just to see if they can. I just think you'd be money and time ahead by either making or printing a pattern and having your wheels cast or by finding similar wheel castings that you can use or modify.

thunderskunk
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Re: CPR G5C Class 1246 Pacific

Postby thunderskunk » Tue Sep 26, 2017 1:01 pm

Using the forge is in no way the subject of the project, and I have no reservations keeping me from using castings. Simply put, I have a forge and a plasma cutter. I don't have a foundry or a water jet table. My goal is to build an engine with what I've got. If I can't, I was gonna run into the back end of my budget anyways, so it was doomed to hit a delay from the start.

I only mentioned it to see if it had already been done. Seems it hasn't.
"We'll cross that bridge once we realize nobody ever built one."

Pontiacguy1
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Re: CPR G5C Class 1246 Pacific

Postby Pontiacguy1 » Tue Sep 26, 2017 1:19 pm

I only ask that because there are some people whose goal is to build a steam locomotive, and there are some people whose goal is to work on building a steam locomotive. In other words: some people like the challenge of building and that is what really gets them going. For some, and I would say most of the people who build a live steam locomotive, their goal is to get a locomotive built so they can then go out and play with it. I was just trying to determine if you were wanting to use forgings just 'because you could' or what. I do think that you'd be better off looking around and seeing what castings you can find that you can adapt. Might can use LE cylinders and valve gear parts for your pacific, brake gear, etc... If you need wheels that aren't available, then you might have to get some casting made.

A plasma cutter and a welder will get you pretty far building a lot of stuff.

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NP317
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Re: CPR G5C 1246 Pacific

Postby NP317 » Wed Sep 27, 2017 11:01 am

Thunderskunk wrote:
"Above each crosstie, I see a flat sheet which goes up to the boiler. Is this a support for the running boards and the mount is just hidden under the boiler jacket? I can't imagine such a thin sheet doing anything for supporting the boiler itself."

I can't make out details for that drawing, however...
On my 90-ton Mikado, those vertical plates (1/2" thick on the prototype) serve more as frame supports to the boiler! Here's my meaning:
The boiler is primarily supported on the frame at the cylinder saddle, and at slides at the rear, allowing for expansion in use without warping the engine frame.
The intermediate vertical plates prevent vertical deflection of the structures, while allowing fore/aft motion so the boiler can change length.
I'll try to attach some picture showing this on the prototype.
My 1/8 scale model accurately reproduces this feature using 1/16" thick steel plates.
~RN
Attachments
Rayonier #90 2007 022.jpg
Rayonier #90 2007 023.jpg
Rayonier #90 2007 033.jpg
Rayonier #90 2007 036.jpg

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Fender
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Re: CPR G5C Class 1246 Pacific

Postby Fender » Wed Sep 27, 2017 11:29 pm

RN is correct about the vertical plates supporting the boiler while allowing boiler expansion. They also serve to tie the boiler and frame together. These aren't really necessary on a live steam locomotive, because of the physics of scale and because the boiler barrel is much thicker than scale on our models. For example, a full-size mikado locomotive might have had a boiler shell that was 3/4" thick. In 1.5" scale this would correspond to 3/32" thick, or just 0.094". But the live steam boiler would likely be more than three times as thick (5/16" or 0.312"), making the intermediate supports completely unnecessary.
Most builders who model this detail will make these plates as sheet metal dummies that don't actually attach to anything at the top.
Dan Watson

thunderskunk
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Re: CPR G5C Class 1246 Pacific

Postby thunderskunk » Sat Oct 07, 2017 11:00 pm

Fender wrote:... the live steam boiler would likely be more than three times as thick (5/16" or 0.312"), making the intermediate supports completely unnecessary.


Awesome. I might drill and tap a few holes on top of the crossties just in case I decide to do it, but probably will not. The running boards are pretty wide, I can get away with missing quite a bit of detail.

I've been mulling over the parts list and making a few op sheets for the past month. It's looking good, I might not run out of money until late 2018! woohoo.....

I'm starting with a cardboard/plywood model, which is helping me grasp how to tackle location control of the driver journal cuts to the cylinder block/saddle. It's a rough model, and it'll be a very interesting fire starter when it's done, so don't expect it to look amazing. I've turned half the living room and the dog kennel into a sort of ghetto locomotive TOC. I got tired of moving furniture every time I wanted to look at two sides of either drawing.

On the full size drawing, there's a couple of tapered 'keys' on the frame face where the saddle fits (see figure). I haven't really noticed this being done on the other build logs. Has anyone done this to locate their frame to their cylinders, or is it unnecessary? I know that using wedges to align and adjust the journal boxes isn't realistic on such a small scale, so I have to imagine this operation has to be high-tolerance.

Saddle location question photo.png

model of model 1.jpg
"We'll cross that bridge once we realize nobody ever built one."

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NP317
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Re: CPR G5C Class 1246 Pacific

Postby NP317 » Sun Oct 08, 2017 10:18 am

On full-sized locomotives, rigid assembly is required due to the forces generated in use. This shows up even as tapered bolts holding the smokebox to the saddle on a Climax geared locomotive!
But our models don't required that degree of rigidity. By making joints tight/reamed bolted fits for items such as cylinder mounts, the final assembly should be quite sufficient.

I recently viewed a video of a G-scale live steam 2-10-0 in action, and could see the left cylinder moving relative to the frame with each piston stroke.
THAT was an example of a too-loose fit!
~RN

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Fender
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Re: CPR G5C Class 1246 Pacific

Postby Fender » Sun Oct 08, 2017 12:49 pm

thunderskunk wrote:On the full size drawing, there's a couple of tapered 'keys' on the frame face where the saddle fits (see figure). I haven't really noticed this being done on the other build logs. Has anyone done this to locate their frame to their cylinders, or is it unnecessary?


This another one of the differences due to the physics of scale. On a full-size locomotive, there are enormous forces acting on the connection between the cylinders and the frame, and if these forces were transmitted through the bolts connecting the cylinders and frame, the back-and-forth stresses would cause the bolts to work loose in their holes. The tapered keys cause these forces to be transmitted directly from the cylinders to the frame. Because the piston area is so much smaller on our models (plus the steam pressure is usually lower), tight-fitting high-strength bolts are usually satisfactory.
Dan Watson

thunderskunk
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Re: CPR G5C Class 1246 Pacific

Postby thunderskunk » Fri Nov 17, 2017 11:14 pm

Sorry for disappearing on ya there. I keep hoping to have more to report, but I haven't done more than pick up material for the frame. It's sitting in a big pile on the bench, but it does exist. I still need to level a few of my machines before I start cutting, and the Army voluntold me for some extracurriculars that have nearly put the project on the back burner.

In the planning process, I'm experimenting with different ideas for the cylinder block. I'd prefer building it up with steel flatstock, as I think that's well within my capability and seems simple enough to wrap my head around, but I haven't seen any clear cut examples of anyone else doing it. If I run dry on the idea, I'll probably cast it out of bronze. I've attached a photo of my silliness on CAD. That particular idea was to cut the channels into the plates and seal them with gaskets, packing, or simply have plumbing reach the nearest plate to the ports in the cylinder liners since I bet getting those plates to seal would be a royal pain.

drawing progress 1.png
"We'll cross that bridge once we realize nobody ever built one."


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