No worries. I have a real issue trying to hit the various “buttons” when I try to use them via the phone!
Eric
Day 8: Of Rods and Decks
To begin with, sorry, @PeterT , I am still learning the names of steam engine bits! I’ll address the issue of rods, first. The cotter pins are supposed to go from the disconnected rod that connects to the rear driver into the cylinder. This cylinder has holes high and low, presumably for the one that is the actual drive rod and the one that is for the “D-valve.” Experimentation showed that the cotter pin should run to the upper hole. Kid-zilla helped me to find tiny little machine bolts and nuts at the hardware store today (~$2.00) when he helped me get paint to match the tender (~$9.00). These worked, but the cotter pins would bind. I made guides using styrene tube, drilled out the holes in the cylinder a bit, and shortened the pins a bit.
This worked great, until we tried to push it along the track. It binds and slides along. Now, when we weighted it by mounting the powered tender on top, it worked pretty well. I really don’t want to lay out that sort of money for weight. I will try shortening the cotter pins a bit more, and, if that doesn’t work, remove everything but the connecting rods. Once the deck is in place, the detail won’t be seen, especially when looking down at the loco as it rolls through the garden.
Puttering with the rod system set me back well over an hour. I was not able to turn to on the boiler backhead at all. To boot, I managed to glue something to the steam dome, setting me back on the painting! Needing a victory, I began working on the deck. This phase began with cardstock at the tightest point on the line.
Once the 1:24 gang and I had the proportions right, I used the measurements to cut the styrene deck and reinforcing frame.
Unfortunately, I forgot to account for the frame when I measured the deck length, so the deck will no extend as far forward as intended. Live and learn!
This will work.
By day’s end, the crew and I had used angled styrene to simulate a frame, and we used scrap sheet styrene to fill those “holes.” Tomorrow, I’ll putter with the boiler and backhead as I determine what to do with the rods. The latter may dictate how I make the safety rails around the deck. I and intendend them to affix styrene posts to the frame and then use sheet to make a cheap wall. I may extend those walls downward and make this a “tram,” adding additional sheet and small styrene rod “hinges” to simulate access panels. We’ll see.
Eric
Bill, space is at a premium…
…and tools, glues, and sandpaper are tending to go adrift, with folks forgetting to put stuff away after use. By the end of the day, there were work stations set on the floor and on the little picnic table in the background. I spent an hour today just getting things back into some semblance of order, as parts and projects were starting to get entertwined.
By long established precedent, material put in a “project bucket” is considered “claimed.” Material in the sundry “gemuckabuckets,” buckets sorted by material type, are open for grabs, though there is usually some discussion about it before the grab is made. Actual model railroad bits, such as wheels, couplers, air hoses, etc. are controlled by me (they actually cost $$$$).
Eric
Well, the lower hole is for the drive rod (piston rod) and the upper is to the valve chamber (not necessarily D-valve, there’s lots of types.)
But the connecting rod from the rear wheel goes to the bottom hole, as that’s how the piston transfers horizontal back-and-forth motion to rotary. You may also note the bottom hole is directly in line with the wheel centers, to assist with even power transmission.
Most early locos had inside valve gear, so all you saw was a rod on a pivot rocking back and forth.
I would say you need a longer cotter pin, in the bottom hole.
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Hope this drawing helps a bit .
Note that the center line of the cylinder is on the centerline of the drivers.
By driving the wheels from the rear wheel, cuts down the amount of the angle that the main rod has to traverse in its stroke.
The main rod is outside of the connecting rods, but attaches to the wheel pin on the same shaft, just outside of the connecting rods for clearance.
The Top hole is for the valve gear to control the sliding valve, to use that hole to drive, you would get binding due to the severe angles from the offset of the pins.
Hopes this helps along with Peters explanation .
Dave T.
EDIT: BTW keep the bearing clearances really loose on the connecting and driving rods bearings, to prevent binding.
I’ll add my 2 cents because when I first started here modeling steam I knew nothing about how a steam loco actually works. So what these guys are telling you I will try to put in layman’s terms. So to move the drivers ( the big wheels on the loco that power it) you have to take a back and forth piston motion and turn it into a circular motion. So inside the cylinders is a piston. Steam is applied to either side of said piston to push it back and forth. Which side the steam is applied to requires a valve of some sort. So coming out of the cylinder is a drive rod (might not have the right name) this rod is driven forward and backwards by the piston. Then you have a connecting rod that connects that drive rodnto the drivers. It pivots on the drive rod end. This allows the end connected to the wheel to rotate at the same time it is moving forward and backward.
So they are right you need to run your cotter pin in the lower hole. What the upper hole is for is another rod that is attached to an eccentric “gear” that is for timing. It pushes what we call the valve rod in and out of the upper hole. This pushes a valve in the steam chest forward and backwards. This valve is what determines which side the steam is applied to the piston.
Dave said this all needs to be lined up with the boiler and there is a good reason for this. Steam is produced in the boiler and channeled through a big hunk of iron that acts as the cradle for the front of the boiler. It has passages in it that allow steam to travel from the boiler to the steam chest and drive the piston. When it exhausts it goes through another passage in that big hunk of iron and into the smoke box. This acts like a supercharger. The escaping steam rushes up and out the stack and in doing so creates a draft that pulls the hot gasses (smoke) from the fire box through the boiler and up the stack. This draft really fans the fire and creates way more heat. Giving the locomotive a lot more oomph.
Hope that made some sense. They are really cool designs and once you start to understand what each part actually does it makes more sense why parts have to go where they do.
Day 9: Rods and Boiler
Gents,
Thanks so much for the education. The bonnie ship CHICAGO, a uranium burner, was steam turbine and considerably simpler. I re-routed the piston rod to the lower hole, aligning it with the piston. It still bound up on the front of the stroke, as the pictures show…
…but at least it fell out of the cylinder entirely at the end of its stroke, unless it bound up somewhere along the way. I am sure there are long dormant math skills I could access to figure this out, and, were this the Laplace or Fourier Challenge, I suppose I would. For today, I set the chassis aside and worked on the boiler.
The 1:24 gang reported for work, and we collected our styrene.
We opted to do our ideating on the cardstock cutout, lest the glue spill and screw up everything.
After salvaging appropriate scraps, I busted into the new stuff, and then sat there as we debated how to proceed. The options were:
- Glue the original top firebox to the cab and build sides and fronts in situ.
- Build a nice frame from carefully measured bits of styrene, assemble it all, and insert it into the cab.
In the end, I opted for option #1.
Beyond not trusting my ability to make a straight cut, I really wanted to build out from the foundation of the cab, using the wall to frame and anchor this part of the project. Despite gluing myself to the cab, boiler, backhead, etc., it came out OK.
It got some Tamiya Putty, and tomorrow it will get some basic details, using a B’mann 10-wheeler backhead as a rough guide.
After this, it was time to take it to the tracks for some ideating. Naturally, I again applied non-Euclidean geometry to augment the challenge.
You’ll note the cab wall doesn’t quite drop to the deck. Schimpf 
A bit of styrene not only helped to support the boiler, but it also hid the gap along the front of the cab.
But how to hide the gaps along the side? That’s when it dawned on me that this is essentially a MOW unit. Toolboxes? No, too high off the rials and no way to access them? Chains and ropes and stuff? Sure…I suppose an open top bin that held items the crew could access from the deck would work. Then I noticed the space in question is perfect for spare track ties! Works for me, and I can use the chains elsewhere.
I have never been happy with the idea of gluing a safety railing to the observation platform. I think that would last exactly one evening before an Act of Dog broke that off. That’s when I remembered some dude wrote to GR about using old wire trays for safety railings. Trays I have not; random mesh I have.
The plan is to bore holes into the deck frame, remove a the lowest horizontal bars, and glue this into the holes. I can cut a bar out to allow the crew to pass through, adding a grab iron and a stirrup step to assist. The gaps are about the width of a tongue depressor, which I can wire onto the mesh for a wall. We have a plan!
Then I went to the beach (Not too long; the water was 74 F. Brrrrr… 
). I realized I have to move forward, so tomorrow I will mask a bit of the deck’s underside to ensure a good plastic to plastic bond, then paint it black. I can paint the cab interior black and fit the roof once I have the backhead done. After final finagling, I’ll mask the points where the boiler fits, again to assure a good bond, the paint the deck black before securing the boiler and cab in place. That should clear the way for the safety rails, spare ties, chains, ropes, whatever. Of course, there are still those rods…
Still, just to kick myself in gear, the cab exterior got a coat of Rustoleum Farm Equipment Green.
That’ll do!
Eric
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Having closely inspected your photos, I understand the problem. 
A real cylinder with a real piston would constrain the piston rod from moving anywhere except back and forward along the centerline of the cylinder.
One solution to your problem would be a tube inside the cylinder that the cotter pin would travel in, so it couldn’t go up or down. The tube could be plastic, brass, aluminum, or whatever.
Another option is a “guide” - a single or dual steel rod (like the ones on the 4-6-0s) controlling the crosshead, which is at the intersection of the piston rod and the connection rod.
Eric,
Capitalizing on what Peter said, a model rocket tube that goes on the launch rod might do the trick if inserted into the lower cylinder and your citter pin could ride inside it? Maybe?
Looking really good so far.
Pete, et all: Isn’t the issue that there is no cross head to support the drive rod where it connects to the piston rod (cotter pin)? A tube inside the cylinder may help simulate that support. If not, another cotter pin coming straight down from the deck with the piston rod cotter pin running through the eye may add more stability.
Eric,
You are right. In-between the “drive rod” (on the bottom) and the “valve rod” (on top) is usually some sort of supporting feature that the drive rod slides on. Sometimes it’s just an upper bar that it hangs on but my preferred look is a rod top and bottom.
I don’t know about later locomotives but 1800s 4-4-0 and 2-6-0 employed this sort of cross head support. The 10 wheeler has a angreat example of it.
Day 10: Boilers and Rods
I didn’t want to get bogged down with the rod issue, so the 1:24 gang and I proceeded to making bits and pieces to suggest a detailed cab interior. We began by grabbing bits and pieces of styrene to make the firebox doors, basic piping, gauges, etc.
I had just removed a busted bell from Kid-zilla’s bicycle, and this guy and I thought the interior doo-dad would be perfect for the Johnson bar!
I found a couple styrene rings that will become gauges…
… and the lads masked the exterior prior to taking the cab to the Palm of Spray Painting…
Ummmm…I’m OK with that!
Alas, the exterior paint had not fully cured, so there is some touch up work to do later.
At some point, the 1:24 electrical shop showed up, so we made fast the headlamp and ran some wires through the boiler. The leads will eventually go to a battery clip I have painted red to emulate a tool box. This will go in the cab. I cleverly made the leads long, remembering short wires invariably lead to broken wires later on as you change batteries!
Not wanting to pay any more holiday time to the boys, I cleaned the surface rust off that cage that will become safety railings and painted it black. The deck also got its black paint. Having learned my lesson, I have set all of this aside for the paint to cure.
With all of these success, I was ready to reattack the rods, armed with the knowledge shared in the preceding posts. I began by filing of the styrene tubes that went into the valve gear. Then, I cut up a bit of piano wire so that I could experiment with different lengths of piston rod without grinding away too much of my cotter pins, which seem to be some unique size. I misread the posts above, and I inserted the stump of that styrene tube to the outside of the piston, rather than the inside.
Whoops. That didn’t work. On the upside, I did get the piston rod length correct, and it neither jams itself into the front of the piston as shown above nor, if properly supported by my fingers, falls out the back, as shown below.
Since I plan to let all my painted stuff cure, I can take the top of the frame off the chassis, get at the pistons, and insert and internal bit of tubing, be it left over brass, bits of styrene, or a rocket launch lug. Naturally, as this chassis hates me, the ring-a-ling thing that held the main rod to the after driver became one with the universe.
If I cannot solder or glue a small washer to the end of that pin, I am not sure how I can keep the connecting rod in place.
For the record, here is our stock LGB m2075 out on the tracks this evening.
30 minutes later, after 40+ years of service (20 or so in storage), it sputtered to a halt. LGB m2075s hate me… 
I am glad that I chose to mount the cab and boiler to a separate deck. It will allow me to work in parallel, at least for a while, finishing those items as I tinker with (or tram up) the chassis.
Eric
Jon, thanks. I was weighing that, too, as I tinkered this afternoon. I hadn’t read your post properly, though, and I wasn’t able to imagine a solution that would let me mount an external guide properly. I kept wondering if there were long, skinny eyebolts…Never thought about another cotter pin.
Eric
My Regner “Else” had no crosshead or guides to support the piston rod.
I don’t understand how that works with the piston rod/cotter pin moving backwards and forwards.
Another solution would be to wrap a ring of wire around the end and add some super-glue or epoxy.
Day 11: Rods
I had just enough daylight today to rustle up the 1:24 gang to address the piston rod issue. We cut styrene tubing and mounted guides inside the pistons.
After remounting the cotter pin to one side, I tried to roll this in my hands and on the track. As expected, the pins struck the forward part of the pistons when the piston rod is closest to the piston. What I didn’t expect was the binding at other points along its stroke.
I connected all the rods on the other side just to make sure there wasn’t some feedback issue between the two sides, and I got largely the same result, just this time on two sides of the locomotive.
I’m at a loss, but, in addition to shorter piston rods, it seems some sort of guide is needed. This weekend, O.S. and I will be at the USS MISSOURI Memorial for its annual living history day, so preparations for that and the event itself will occupy my time through Saturday, giving me time to ponder this and paint on the cab to fully cure.
Eric
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On the cotter pin from the deck as Jon mentioned you will need one with a bigger loop than the one you are using as the rod. This way the hole in the larger cotter pin maintains a full ring as a guide for the rod, and the two legs of the larger cotter pin will look like one piece coming down. Anything or way you can make this configuration, from what you have on hand, should guide your way. Hope that is clear enough .
Does this help?
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The tube inside the cylinder, guiding the piston, has to be a snug fit on the piston rod/cotter pin and fixed securely so it doesn’t let the piston rod wobble.
I am still totally at a loss as to how the hanging cotter pin/guide works. As the piston rod/cotter pin is moving backwards and forwards, surely it will collide with the hanger?
Eric, can you post a photo of the side of the chassis with the pin/piston rod all the way forward, please?
Well the way I see it , Eric has two options. You could tear off all the side rods make it diesel powered and call it done. Then use the steam chambers to carry water,fuel, etc.
Or you could keep the side rods and make a crosshead with a sliding eccentric on the one rod which holds your timing rod in the chest. (forgive me on my steam terminology) .
Or you could just Sh#T can the side rods as they are just a fad anyway and go diesel. Everyone is doing it these days anyway. Then you could add HEP cabling and ditch lights with a roof top gen set!
At this point you are wasting precious MIK time on stupid side rods! Gut it and move on with important features like dynamic braking and MU ports!