jtlan
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Everything posted by jtlan
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Looking good. Is this a model of a particular locomotive? In a lot of cases the "L" size drivers wind up being too small.
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I've found that the official Lego drivers are cheaper on Bricklink than the price Big Ben Bricks sells their wheels at, but the official wheels only come in red and black. Big Ben Bricks makes a variety of colors (no light grey any more for some reason though, although they clearly used to), and an XL and M size. For L size wheels in black or red though, I'd use the official wheels. They can take an O-ring for vastly improved traction, and also look a little better because of the counterweight molded into them.
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It'd probably be easier to build directly on top of the studs on the train motor. You're going to wind up with a pretty fast vehicle though.
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After the last boxcab, Commander Wolf and I figured we had to go smaller. And slower. So we decided that both of us should build a motorized model of a GE 23-ton boxcab. We agreed to build them models independently, then meet up and compare approaches. We started with the same scaling image: Since there was some variation among the prototypes, choice of details was a matter of taste. I took most of my references from here. Here's my finished model: The original locomotive is really tiny, so I tried to keep the model about 7 studs wide. There's a lot of SNOT in this model: The main chassis is upside-down, the deckplate and frames are held against that using Technic pins, and the body attaches to some jumpers on the deckplate: The battery box is mounted sideways in the body and the power switch is reached by jabbing an antenna through the window. The roof is actually only held on by gravity: Originally I wasn't sure if I was going to put the caution-stripe tiles on the frames, but codefox421 vouched for them. You can see the full Brickshelf gallery here. So, what did Commander Wolf do? Read on...
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Do the motors actually feel hot to the touch, or do they just stop working? I know a lot of clubs remove the thermistors from their 9V motors, which appears to be a common repair for motors that stop after running for not too long. While the thermistor is there for thermal overload protection, I've heard that it is a bit overzealous (and only gets worse with age).
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A layout like that with no sneezeguards / barriers? Your crowds are much more well-behaved than the ones my LUG gets at our displays...
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WIP - Persian Blue Steam Express - 4-6-2 - Model T
jtlan replied to dylanfarrow's topic in LEGO Train Tech
Hey now, if it's an inside-cylinder engine, there wouldn't be driving rods visible on the outside, only connecting rods (and even then only if it had two or more coupled driving axles). -
WIP - Persian Blue Steam Express - 4-6-2 - Model T
jtlan replied to dylanfarrow's topic in LEGO Train Tech
Maybe it's a fireless locomotive? -
WIP - Persian Blue Steam Express - 4-6-2 - Model T
jtlan replied to dylanfarrow's topic in LEGO Train Tech
Welcome back! Digital tools are great for returning builders, since you get to play around with all the new pieces before buying any. To make the LDD version easier to see, switch on "show outlines on bricks" in the options. I really think that should be the default. Also, no smokestack? -
This looks pretty slick, but I can't help but think that the model should use the normal blue rather than the dark blue, based on the photo of the prototype you included...
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Right now your driver go (from front to back) Blind-Flanged-Blind-Flanged. Swap them to get Flanged-Blind-Flanged-Blind. This will make the front overhang better at the expense of the rear, but there are no pistons in the back to cause trouble. To deal with the increased angle at the back, lengthen the connecting link between the rear truck and the drivers, so that the link connects somewhere between the 3rd and 4th driven axles. The BR55 is an 0-8-0 (UIC: D) wheel arrangement; porting Duq's solution without considering the new context (in a 2-8-4 / 1D2) is a recipe for disappointment. You did the right thing by trying this before you built any more of the locomotive though; I often see people who build a detailed body without thinking about how the chassis will work.
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Not having driving rods at all (or having fake ones) is another possibility: Commander Wolf's 5AT takes this approach. Option #2 is good, but be prepared to spend a lot of time tweaking the chassis before you start building the body on top. To put functionality first you have to build bottom-to-top.
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An important lesson to learn (and one that I know that many builders haven't already learned...!). Good thing you learned it here on a diesel locomotive instead of something more complex. As mentioned in one of my earlier posts, you might consider using the three-axle truck design from Railbricks #6, powered using PF M or L motors. You should be able to power both trucks if you're willing to sacrifice the interior of the cab.
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PF Battery Box or PF Rechargeable Battery Box
jtlan replied to legotrainfan's topic in LEGO Train Tech
While this is generally true, I suspect that it's not the case for the Lego battery, where the charging regulator and associated circuitry are built into the battery box. -
I don't think that will work -- half-beams (like these) have a thickness of 1.25 plates...
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The thing is, there's not a good definition for what constitutes "k-wide". Measuring the widest point on the locomotive is unsatisfactory, since that would imply the Emerald Night is 10-wide, and basically any steamer with driving rods is 8-wide. "Main width of the body" is better, but doesn't account for cases where parts of the locomotive are built with SNOT and therefore is wider than the chassis would suggest (plus, "width of the body" is vague). If your goal is to make an accurate model of a locomotive or rolling stock, then you should pick a scale ("k-wide" doesn't count as a scale), then scale up/down drawings of the prototype based on your chosen scale to get the correct dimensions. The actual width of models will then vary based on how large the prototypes were -- at the scale I use, American stuff tends to be ~8 studs wide, British things closer to 7 studs, smaller locos all over the place ... etc. A different way to think of it might be this: You want to add more details and functionality to your train. 6-wide isn't big enough, so you just have to "build bigger" by widening the base you build on. I suspect 7-wide was initially an attempt to build "a bit bigger" without going all the way up to 8-wide. However, the sheer size of some real prototypes won't be conveyed correctly without using larger sizes.
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Here is a presentation from Ben Beneke about building in 7-wide. You might find some of the techniques he demonstrates helpful.
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As mentioned previously, any aftermarket charger with a voltage in the appropriate range will work just as well; it will also cost much less. See this thread for more details.
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[MOC] Norfolk and Western General Electric U30B
jtlan replied to Commander Wolf's topic in LEGO Train Tech
This part, specifically. I'm not sure how well the other colors match Lego; the black tubing is a little glossier and there's some text printed on it. A number of my locomotives use it. -
That seems reasonable. I don't have loco parts in front of me right now (much less your actual model), so I had to go off of theoreticals. I'm also surprised that normal slope bricks don't exist in dark tan ... is the color relatively new? Another option for the side-rods is to use half-beams instead, although the rods will not all be in the same plane in that case.
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Spot on for scale? I'm not sure what your intended scale was, but your wheelbase is 10 studs (consider the distance between the centers of the axles), relative to the real wheelbase of 12 feet. At that scale, the wheels would be: 48 inches (prototype driver diameter) * [10 studs / 144 inches] = 3.33 studs --> 26.67 mm. The M drivers have a hub diameter of 24mm and a flange diameter of 30.4mm, compared to an L driver's diameters of 30.4mm (hub) and 36.8mm (flange). It seems like the M drivers would be closer, since the flange visually forms part of the diameter of the wheel on the model. The hose should be sufficiently rigid for this, in particular as it doesn't look like your locomotive is powered through the drivers so the only force going through the rods would be that needed to turn the drivers when the loco is pushed. If you're worried, you could insert some stiff wire inside the tubing, although I'm not sure if you count that as cheating.
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This is pretty good, especially in light of the limited parts selections. If you used Big Ben Bricks medium drivers (a better fit given the size of the loco, I think), you would be able to lower the entire frame by 2 plates, allowing you to line up the running plate and buffer beam again. Have you considered using clips and rods/flex tubing to make the connecting rods? That would lighten the visual "weight" of those rods, I think.
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Unless you have something that keeps the lower bevel gear on the vertical shaft from moving, with this setup it looks like that gear will just skip upwards and stop driving the wheels. I would suggest using some of the older Technic beams, frames, and plates, if you can spare the room, as that often with give better support. Alternatively, insert a spacer between the lower bevel gear and the red supports -- it looks like it might be a bit too small for a half-bushing though.
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I doubt there will be any gear slipping problems -- if there are, it's an indication that your framing structure isn't strong enough. Unless your goal is to go screaming around the track at top speed, the L motors are going to be way better than the train motors because they can put out good power at a sedate speed. I'd actually even vouch for lower than 1:1 gearing. You can see some power-testing results here. Unfortunately I haven't yet run any tests with the PF train motor.
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As I mentioned, this might work, but I'd be concerned about the long distance from the turntable on the front truck to the flanged driver. You may have better luck if you move the turntable on the front truck more towards the rear of the locomotive. Also, what's keeping the 1x5 half-beam (the "piston rod") from flopping down? It looks like there might be a few too many degrees of freedom in the entire connecting rod assembly.