jtlan

Are you talking about the online Pick-A-Brick? They're there, under "Transportation", listed as "Prepack Flat With 2 Axles". If you click on the part in LDD, it'll display the part ID# in the bar at the bottom. You can then enter that ID# into Bricklink to search for the part.

This is looking great! Have you been able to test it on 9V track yet, where you might get less friction than on the PF track? Where'd you get the wheels?

At 7-wide, the model should be ~51 studs long (I'm assuming the loco is ~ 10ft wide IRL), so I'd definitely lengthen it. Accurately modeling American anything at Lego scale is tricky. Do those have rubber tires on them? If not, I suspect you're losing a good deal of traction when operating with those.

When I first read the thread title I thought it was going to be about using SNOT technique on a locomotive called "Bullfrog"… :/ If you're in the US, you could try ordering O-rings from McMaster-Carr; I've previously picked up replacement drive bands for 9V train motors and Lego L drivers from there. Looking at your locomotive, couldn't you just power it through the two huge wheels, which already have tires?

The current design you have forces the axle to pass through four holes, which greatly increases the odds that the axle will bind up and not turn smoothly. I'd vouch for either greatly enlarging the holes on the inner frame, or removing them entirely (just don't have the frame descend that far). Alternatively, keep the inside holes, but don't have the outside ones fully enclose the axle (the design used on the outside frames of the PF train motor). What 3D printer / Shapeways option will this be printed on? Most 3D printers can't hope to get anywhere close to Lego's tolerances.

It helps support the motor frame piece, which has a corresponding bump that fits in the hole. You can jam a stud (or the head of a half-pin) in that hole, but it's not a very strong connection.

Nicely done. Locos built in black are hard to photograph; I'd suggest taking the pictures outside on a cloudy day, when it'll be bright enough to bring out all the details but you won't get glare off the bricks. Lego Digital Designer is actually reasonably straightforward, and I've found it extremely helpful for prototyping before I decide if I want to buy a gigantic number of parts. I'd encourage trying it if you haven't yet.

That's a charming little loco. If you're short on space you might consider doing a point-to-point shunting layout (no loop).

Cute design -- the gold accents really bring out the charm. I've got some narrow gauge stuff in the works (waiting on parts…). Wound up building a boxcar as a power unit (9V battery box and gearmotor hidden inside). Really, what Lego should have done is make the 4W curves without the connecting system at the end. There's no point to re-using the connector from the 9V system since the track is smaller, and then you could just connect it directly to the 12V rail pieces without any tricks. I've seen some narrow gauge switch designs on the web, but I've yet to find one that uses the 4.5/12V track without stressing pieces.

Also interesting: The sides of bricks have a very small draft angle to enable them to be pulled from the molds, meaning that the sides of the brick are not exactly perpendicular to the top and bottom (this also means the top of the brick is slightly narrower than the bottom).

That's a picture of 7897 in 1974's photo above, not 60051. Anyone who has a 60051 care to weigh in on the fit of the single-piece nose?

It's making that sound due to the Pulse Width Modulation (PWM) used to control the motors. Essentially, to run the motor at a lower power the receiver switches power to it on and off very quickly, but the pulsing produces an audible sound because the switching frequency is in the range of human hearing.

Since the battery produces 3.7V, I assume they are Lithium-Polymer cells. My understanding is that some specialized knowledge is required to safely connect them in series (cells that are not properly "matched" may overheat and explode). You can buy premade two-cell packs that produce 7.4V (one of these is inside the Lego battery). Lithium-Polymer cells require specialized charging circuitry (plugging them directly into a power source will result in flames and much sad for you). The Lego rechargeable pack contains a charger inside, which is why it can be "charged" by plugging it into the wall (incidentally, this also explains its cost). @Legoroni, you may be able to find a NiMH battery pack that will fit inside your model. You'll still have to buy some specialized charging circuitry. In addition, NiMH packs are much heavier, although that may actually be beneficial for a locomotive. Can you give us a diagram of your intended electrical setup?

Thanks for the kind words everyone. I'm hoping to be able to run it on a club layout soon -- the small loops I own are just too cramped for this monster! No plans currently. Since there's not much space between the drivers and the idlers either the width of the model or the shape/positioning of the pistons would suffer, and I felt those were more important (I did try to get it to work though). That said, if I come up with a good mechanism for doing so….

Thanks! I had been wondering about the color; in particular, it was hard to tell from photos whether dark green or normal green would look better (infuriatingly, the official Lego name for this color is "dark green", and what we think of as dark green is "earth green"...). However, a number of parts I wanted to use weren't available in dark green (such as the arched roof, and the curved 1x4).

Greetings Train Tech, Here is my model of No. 2096, the first Franco-Crosti locomotive. The idea behind the Franco-Crosti boiler system was to use the exhaust gases from the locomotive to preheat the water, thereby recapturing some energy that would otherwise be lost and improving efficiency. Although the concept originated in Italy, No. 2096 was actually built in Tubize, Belgium in 1932. As you can see, it's absurdly large. The wheel arrangement is 0-6-2 + 2-4-2-4-2 + 2-6-0 (UIC: C1'+1'B1B1'+1'C). It's a quadruplex! This project initially began as a joking suggestion for a way to use up all my spare large drivers. I decided to do some preliminary scaling for fun, then downloaded LDD to try to do some mockups … the entire thing quickly spiraled out of control (I wound up buying new wheels, defeating the point of the original suggestion). The end result clocks in at 80 studs magnet-to-magnet, at roughly 1:48 scale (155mm/plate, or 15in/stud). I got all my reference information from here. As all the photos were black and white, I had to take my best guess with regards to the paint scheme; I wound up choosing the Belgian Railways livery used at the time (if my research is correct). I had been somewhat uncertain how well the green would turn out, but I'm quite pleased with the result. As a nice bonus, it matches 10015 Passenger Wagon quite nicely. 2096 is my first foray into Power Functions -powered locomotives. In the past, I've always pushed my steamers using some rolling stock with 9V motors, but I was worried about the stability of such a long locomotive when being pushed. Initially I had been planning to have the locomotive powered by four of the old 9V motors (one for each set of drivers), but quickly realized it was going to be too difficult to fit the motors, receiver, and wiring inside the locomotive. Luckily, I came across a good solution for mounting two PF Medium motors inside the center unit, so I switched to those (which also eliminated the need for PF converter cables). As was the prototype, the model is nearly rotationally symmetrical, and runs equally well in both directions. It drives through switches and any sort of curve arrangement, although I haven't yet tested against flex track… Full Brickshelf gallery here (once moderation finishes). Thanks for reading!

I chuckled as I scrolled through the pictures, then lost it at the crew photo. Well played.

Is there something amiss with the V2 receiver? I thought the V2 was capable of higher current delivery, which would make it a better choice…?

They appear to be Big Ben Bricks medium drivers.

The truck and its axle don't have to move, but the pivot point of the truck can be moved back a bit. Currently, your pictures show the pivot point as slightly forward of the cylinders. Putting the pivot point near the driver axle will probably improve your stability somewhat. As a side effect, the pony truck will turn through a somewhat smaller angle as you go through curves.

10 is the axle-to-axle spacing; imagine if you drew a point in the middle of each axle and measured the distance between those two points. Thus the distance between the end holes on a Technic beam with 11 holes is 10 studs, which is what you have here. I would move the pivot point for the pony truck farther towards the back of the locomotive for additional stability.

You can use the Power Functions extension cable to connect PF equipment to the old 9V motors. I would highly suggest not exceeding 10 studs for the axle-to-axle spacing between the flanged drivers. Although your locomotive probably won't derail if you exceed this by a bit, you'll start getting some serious scraping in curves.

Looks good! It really captures the feel of the prototype, and it's quite something to behold with all the valve gear moving. I always think about making valve gear and driving rods, but usually wind up sacrificing them in order to get the shape of the cylinders closer, or because the wheel spacing makes a rigid cylinder arrangement impossible. The last set of pistons looks to be slightly too far back; if you look at the prototype they're directly under the cab, so it might be worth moving the rear set of drivers forwards a bit. I'd also suggest putting some 2x2 round tiles on the front of the technic liftarms (as cylinder covers).

I'm not sure that that will work with a 3-axle truck; it'd probably be better if the center axle slid. Presumably you've tested it around curves before. In practice, I've found that for 2-axle trucks 10 studs axle-to-axle is the limit (that's equivalent to the standard wheelsets with 7 studs in between). I'd also suggest flipping the 1x2x2 panel window on the cab upside-down, so that the top and bottom edges of the window will align better with the windows at the front. An alternative might be to use the newer window frame instead.

I tried using the old 9V motors for a locomotive I was building, due to their low rolling resistance, good torque, and amazingly low power consumption. They're also the motors I'm most used to using. The weakness of those motors is that the magnet inside (as seen here) is quite fragile; a sharp impact can cause them to shatter. A motor in good condition should run smoothly and relatively quietly; you should be able to spin the shaft and have it freewheel for a while. If the magnet in your motor has cracked, there's essentially nothing that can be done about it; it's usually pretty obvious when the magnet has cracked, because the motor will have a lot more resistance than is normal. (Keep in mind that there are two versions of the motor (71427 and 43362), and 43362 has more rolling resistance than 712427, though not so much that you could confuse it with a broken motor.) My advice to you is that unless low power consumption is a priority, you should use the Power Functions M motors instead. A single PF M motor produces almost as much torque as two of the old 9V motors, while also turning at a higher speed (see this comparison). The odd form factor (~ 3 studs x 5 studs x 3 studs) may make it tricky to work with.