bogieman

Well done! Impressive how well it works with the long cars and tight curves. Dave

Agree, great job! How big is the base area in studs? Dave

FWIW, on my home layout I have a number of vertical transitions between flat and grades that are more abrupt than I should have made them. In order for my steam locomotives to stay on the track, I need to leave a vertical gap between pilot bogie and frame that closes when entering an uphill grade and then there needs to be enough flexibility to allow the pilot bogie to "droop" when entering a downward grade. I have found using tungsten putty to add weight to the bogie keeps it on the track - I stuff it into the underside of the bricks making up the pilot bogie. On trailing bogies, I have found it best to use a suspension loaded by rubber bands acting on the tiles atop the trailing bogie to keep it planted on the rails since the trailing bogie has the drawbar to the tender attached to it and the tractive effort from the drivers is passing thru it. Dave

Well done, especially like the bogies! Clever use of the "Slope 18 2 x 1 x 2/3 with Grille" for the dynamic brake intake, at least that's what I think you used. Dave

Terrific accomplishment to get the color scheme in all bricks/plates, no stickers, in spite of the cost in part count.

That's very clever how you did that, love it!

Wonderful work with all the details particularly on the boiler. The red undercarriage and wheels really sets it off. Dave

Thanks for letting us know that aliexpress now sells the three way switch. I've had one for several years from Trixbrix that the clone makers likely copied, although they used Lego-style throw levers while Trixbrix has their own style. Your link led me to another seller with ballast plates for straight tracks. Until this time I have avoided ballasting but am now ready to so ordered 100 to get started. Dave

Really well done! Nice job on the tapered ends and it's hard to tell but it looks like there are angled sidewalls as well.

Gorgeous work, look forward to seeing it in bricks! I'd be a customer if you were interested in selling instructions.

Thank you. As far as what I modified from Morningstrummer's model to fit the XL wheels, pretty much everything. The XL wheels require the wheels be spaced 5 studs apart, where his model using the Lego drivers has a spacing of 4 studs. I tried to make the change using his basic design for driver bogies made from all Technic liftarms but I wasn't happy with that so went with Technic bricks and ended up with bricks and plates but much of that was also due to substituting Circuit Cube Cubit motors for the Lego L motors. Zephyr does offer rods with either spacing, just have to be sure to get the right ones. Dave

I considered ordering one today but the cost of shipping to the US is $34 which added to the price of one keybrick is too much for me.

Very nice build, thanks for sharing. Dave

Agree, great work!

Terrific job! The PUP components are so neatly integrated. How difficult is it to change the batteries in the hub? Dave

Thanks! There's many corners to this hobby, I'm in a different one than that.

Agree, nice job. Any thoughts of motorizing any functions? Dave

I, too, wanted to know how much current the motors were drawing in operation so bought a cheap DC volt-amp meter on Amazon and wired it into one motor's power leads. I posted a video showing the meter while pulling the same train in the previous video. It shows at 3/4 throttle, the motor is drawing between 400-500 milli-amps at a voltage of about 5.2V ; at full throttle (28 on the controller) it's drawing about the same current at 6.1V. I'll eventually learn what the longevity of the motors are at these current levels. The video is here: I think the slow speed performance is most impressive, at the start of the video the throttle is set to position 2 of 28 and the loco starts moving slowly and smoothly at 1.5 volts. Dave Thanks so much!

Wonderful job! Those Circuit Cube motors are terrific.

Thanks much, opens no problem for me.

Looking forward to seeing it on Rebrickable and a video. It looks like much it is common with the Lego Coaster, which I have. Any chance you could offer a parts list that is additive to make your version from the Lego set 10261?

Nice work! Love the colors with the tan and dark red with the dark green windows.

Thanks Benn, now you see what I needed those rods for! I was as surprised, as I expect most would be, that those little Cubit motors do such a great job in such a big locomotive. The Tsunami decoders allow you to set a 3 point volts versus throttle position curve (28 throttle steps). I have it set only with two points so it's linear from 0 to 7 volts, the Circuit Cube outputs 5V so I am allowing some overvoltage. What you see in the video though is the throttle set to about 80% of full so it's running at about 5.5 volts (I haven't tried yet to measure the current but I need to do that.) I do confess I first ran it with the full battery voltage, 11+V, the default setting of the decoder and after running about 20 minutes I turned a couple of the motors to bricks. All my freight cars have ball bearing axles (BrickTracks wheels and axles) and I also changed the locomotive and tender axles to ball bearings as well. The loco has pulled longer trains than in the video but I'm being a little more conservative now. With the 1:1 gearing the loco speed benefits from the XL drivers but it does load the motors more. I should also note that MorningStrummer did an outstanding job on the tender 5 axle rear bogie design - axles 2 and 4 are fixed to the bogie frame and axles 1,3, and 5 slide laterally as required in curving, all very smoothly with not much rolling resistance. Thanks so much for the kind words Thorsten! Dave

Thanks for your supportive comments.

There's been quite a few Union Pacific Big Boy locomotives done but I had to try to build one for my home layout. Most recently, Berthil graciously posted this thread and free instructions for his model: I look for inspiration in models other have built and was especially intrigued by MorningStrummer's model he sells plans for on Rebrickable: https://rebrickable.com/mocs/MOC-89126/morningstrummer/4014-big-boy-version-2/#details I particularly liked the motor arrangement he developed putting the motors on the two driver "bogies" directly rather than in the boiler and running shafts down to the driver axles. I then learned thru a build video on YouTube that MorningStrummer's model was being sold as an authorized kit by Letbricks: So I purchased that and assembled it to see how well it worked. Being a retired mechanical engineer, I just can't leave well enough alone. I found two major items that I felt would improve the model in my application. First, it is advertised to be at 1:40 scale whereas everything I have built to date is 1:48 scale - I found it to be too big relative to my other cars and locomotives. Second, it uses Lego steam drivers 85489a&b (size L per the Brick Train Depot wheel chart) which I feel are too small to get the "right" look yet are the only option available to keep it all Lego. At 1:48 scale, these wheels scale to 57 inches versus 68 inches that the Big Boy used. So I decided to re-scale MorningStrummer's design to 1:48 scale and use Big Ben's XL drivers. I ended up changing a lot. The larger drivers require a spacing of 5 studs, versus 4 for the L size wheels; after much work on stretching the technic driver bogies I ended up scrapping that design and building with technic bricks instead. I had bought some Circuit Cubes Cubit motors to try out a while ago and decided to try them here since they are so small (2x4x2 high) and fit easily. They exceeded my wildest expectations for their power. Each driver bogie has two Cubit motors for 4 total, no driven axles are in the tender. This is the trail driver bogie before I made some other changes that shows how nice the Cubit motors work: It's hard to see but I milled a small recess in the rear of the Cubit motor case that allows a Bar 4L slightly shortened to fit between the technic axle 1L with pin (3749) that keeps the pins aligned better to prevent them wobbling in the technic beam hole; the side rods keep the wheels synchronized. On my first steam locomotive, built from Tony Sava's Southern Pacific Daylight GS-4 instructions, I experimented with a Seuthe smoke generator before switching to a water mist generator I designed and 3D printed. Based on that system, I designed and printed a two stack mist generator with a large water reservoir for the Big Boy. To get more realism, I thought about how I could create a puffing of the steam synchronized to the driver rotation which would be especially evident at low speed. I found a cheap inductive pickup on Amazon that I thought I could integrate into one of the driver bogies and created a mockup to test it out which can be seen in this video: I was able to mill down the width and length of the pickup to fit in a 2x4 stud space without damaging it. It's simply wired to apply the 12V power to ultrasonic mist generator control board when the pickup detects metal. I ended up machining a trigger wheel that is on the lead axle of the trail driver bogie pictured here: The mist generator uses two 16mm discs fed from a common reservoir. The assembly connects and supports the smoke box of the locomotive to maximize the water capacity which is enough for more than 1/2 hour. It's printed in 3 pieces as shown here: The driver arrangement is F-B-F-B in the lead driver set and B-F-B-F in the trail driver set. It negotiates R56 curves but struggles on R40 but that is not a problem on my layout. I placed the driver bogie pivots as far as I could away from the center of the loco to limit the swingout of the cab on curves but it still can't make my outer loop because the track is too close to the wall in few places that's not easily changed now. The video shows pulling a train around the level loop of the layout (pardon my grandkids play area). The steam out the stack (mist) doesn't show up very well in the video particularly against a gray or white background. The Seuthe smoke showed up better but it leaves an oily residue that I did not like. Using distilled water, the mist leaves no trace. With the modified driver spacing, this fits Zephyr's Trained Bricks rod set sold for the Brick Train Depot Big Boy model which is what is seen on the model. For powering the model, I am using 3X 18650 Li-ion batteries powering an AirWire Convertr C-60 that gives wireless control to a Tsunami2 2200 Big Boy DCC board. The Tsunami board only powers one of the four Cubit motors but generates the sounds via a speaker in the boiler. There is a second Tsunami2 4400 board that drives the other 3 motors and controls the lights and mist generator which is wired in parallel from the AirWire board. One Tsunami2 4400 could control everything but only the 2200 is available with the Big Boy sounds. The batteries and AirWire receiver are in the tender, the rest of the electronics are in the boiler. I made class lights for the front using Plate, modified with Light Attachment (4081b), by drilling a .09 inch hole in the ring, gluing two 0806 LED's to a bar milled on two sides at 90deg, on flat to pass the front LED wires, the other to mount the side LED seen here: The model is now about 1/3 Lego parts, I will say the quality of the Letbricks parts is a step below real Lego parts but not terrible. Clutch is uneven, some are tighter, some looser. I hope I haven't offended anyone with my part modifications, 3D printed parts and starting from non-Lego parts. Dave