GeorgeCrecy

Howdy efferman, That is absolutely wonderful! Go ahead and send that over to shapeways and I'll be very set.

Hey efferman, Ah, I gotcha. Given how this will move, only axle connections should suffice for the whole thing, both for the top "flange" and for the two sides. Also, take a peek at the picture I linked in my last post if you like a sneak peek!

Hey there Efferman, This looks fantastic so far! And actually, a combo of the interlocking feature with the axle connection would both match the look and be even stronger than a pin connection. The only thing missing is just one of the halves to "flange" up as shown in the example image, with another axle hole in it and offset to one side rather than centered in the flange to allow for this whole contraption to connect with something further above it. And to answer your question, it's this size because I'm making a working minifigure-scale model of the Titanic's Reciprocating Engines, and this was the one thing I couldnt achieve with existing parts. https://i.imgur.com/BUtdc7u.png?1

Hey there mdemerchant! I certainly don't mind the flipping idea, but my one issue with the design is how easily one the bottom plates could pop off if the mechanism moved. Regarding the main axis of the crankshaft, I wouldn't be using the middle of the 4x4, and would instead connect a 2x2 to one side on top of the 4x4, and that would be the center of the crankshaft, thus leading to an offset rotation. Take a look again at the gif if I am explaining things terribly, as I am won't to do.

Hey again Efferman! I had tried contacting you a while ago, but I'm gonna just redo my request for brevity's sake. I am hoping to request you design a Stephenson eccentric strap that can fit and lock around a 4x4 round brick (6222); basically a circle cut in half and hollow, with axle joining areas on two sides, and an axle hole on top of the top half. Please see the gif link and image of a roughly machined (non-lego) example below: So all told something 6x6 or slightly smaller, and preferably between 1 and 1.5 studs wide. I am hoping that some axles with bushes on both ends can hold the top and bottom half together while still allowing the 4x4 round brick inside to turn. Let me know what you think!

Hello one and all! I am hoping for some help in trying to make a Stephenson eccentric as showcased here: I am namely needing the bottom round area replicated; something that can surround and lock around a 4x4 round brick (6222), and have an axle opening upwards. So ideally in stud size not exceeding 6x6 and 1.5 stud in width. As of yet, I haven't had much luck figuring it out and am almost to the point of looking for someone to custom print the two or four needed parts. Any ideas or designs would be highly appreciated!

Well howdy again everyone! At the risk of reactivating an old thread, I have an update to my work recreating these old engines. Attached will be some images of the Reciprocating Engine (with cylinders courtesy of Tommy's design): Next, I have a slightly revamped version of the Electric Dynamos Obviously, some things aren't showing as connected because connecting such things in LDraw is a pain, but I am very confident that things will come together well IRL. I am also finally confident enough with the design to get to ordering the parts and seeing if all this theory will work! Some designing still remains to be done for the eccentric-to-switch connections, but beyond that, this project is going along smoothly. The next challenge will be the creation of the center Parsons Turbine that will operate via the leftover air from the engines and dedicated supply combined. Leftover air from this Turbine will then be channeled to the "condensers," which in reality will be two lego-made compressors that refill the air tanks hidden in the boilers. Let me know what you guys think!

Hey there DrJB, Not at all, I appreciate the further input. As I think I mentioned earlier in the thread, I probably misnamed the title of the thread that has made people misinterpret my question. Perhaps a better name for what I have in mind is a moderately "self-sustaining" system with use of different subsystems. Those subsystems would include 1) tanks of compressed air, 2) two pneumatically-powered triple expansion engines, 3) four to six pneumatic electric generators (each using a PF XL motor), and 4) two Lego-built compressors. If we were to combine any excess air leftover from the pneumatic engine/generators AND surrounding air as well, would such a system be able to keep up with itself, more specifically regarding electric output and input? Looking up a bit of statistics, it looks like the Power Functions Large motor uses about 80 mA of power on no-load (see here), and the PF XL motors use 120 mA. In videos it seems that they output only 1/2 to maybe 2/3rds that amount of power if used as generators. Does anyone have any proper stats on what kind of power these motors can provide? Thanks again for everyone's replies thus far, and I apologize that I am such a dork mechanically and terminologically speaking.

Hey there efferman, I apologize for not getting back to you sooner. For some reason I'm not getting thread reply emails. No, nothing would be under torque. And of special note is that the sheaf would need an axle hole rather than a pin-type hole. Thank you again for your time and I look forward to hearing back from you!

Hey there everyone, Wow! I need to check my settings, I got no notifications about this thread getting replies. In any case, I realize this is quite theoretical, and that the lego pneumatics introduces many opportunities for leakage between connections, but here is what I am mainly trying to accomplish in a better way than I explained originally: I am attempting to recreate through lego multiple pneumatic engines powering different things, and these pneumatics being supplied sequentially from multiple custom air tanks made from plastic bottles for longer run times. There would be four things needing air: 1) main reciprocating engines under some load, 2) a "turbine" also under some load, 3) electric generating engines, and 4) the return to the bottles. I suppose it isn't entirely necessary to reuse the air for the compressors when I could instead reroute any leftover air for another purpose I have in mind. But, as others were mentioning there might not be enough leftover and/or other problems might also arise. So perhaps it would be better to use the term closed-loop in regards to the electric generators helping to power both the compressors (regardless of where the incoming air comes from) and lights for the overall build. And regarding the turbine, especially for like a 10-12 stud wide cylinder for it to be the scale I am intending, it might be better to just hide a smaller and easier to build turbine inside. Anyway, thanks to everyone for your thoughts on the idea so far, I look forward to any more feedback, and if I can I will see about testing my model IRL. We shall see! P.S. For any interested in what in the world I'm trying to do with this, I might direct you to a previous post of mine where I have some in-progress pics of the engines themselves (in LDraw): https://www.eurobricks.com/forum/index.php?/forums/topic/156278-need-help-replicating-historic-engine-system/&tab=comments#comment-3171756

Hello one and all, For those that have more experience with pneumatic systems, I was wondering if a self-sustainable, closed-loop system is feasible with LEGO pneumatics? I have been toying with the following idea in my mind: Air tanks lend air to an engine and to a power generator, leftover air from the engine going to a turbine, and from that to two compressors. Power from the pneumatic power generator goes to the lego-built compressors which resupply air to the air tanks. Would such a system work? Or am I looking at a pipe dream (pun intended)?

I'm not sure I understand the relevance. Was there a particular part you were referring to, Josie?

Hey there Efferman, You have some awesome work on here, and I wonder if you might be able to help me? I am looking for a lego technic-ized version of an eccentric as below: If you look at the second picture in the spoiler, the idea would be a central circle the same size as part 4185 the Technic wedge belt wheel, but with a flat face instead of how it juts out in the picture above, and with an axle hole towards one side (see O in the first picture). Perhaps doing without the packing, then having the two straps that can close on either side of the sheave, leaving the holes for an axle and bush to take the place of the bolt and nuts shown. Lastly, the top strap would preferably have an axle connection that can lead vertically from the whole body (see N in the first picture). Do you think this might be possible?

Very nice Tommy! I'll see what I can come up with from here. On a different note, I am happy to report that I think I solved the eccentric issue, though it isn't as clean as I would like. It does use the pully wheel part, part 32126 with a 1/2 technic pin to join to the wheel, and on the opposite side are two 2 x .5 technic beams with technic axle 2 connecting one end. Given that there are two eccentrics right next to each other, I also had to figure out the connection system between the two. I am the worst person for this project given my complete inadequacy for anything mechanical, but below is my attempt at it, and it fits in the model pretty well! Such a problem might seem basic to others, but I'm a history major, and not at all competent in anything beyond theory. Further, the idea would be to glue the connector to the pulley wheel so that it doesn't shift around, and I included the universal connectors as there is some pretty sharp angling going on between these and the reversal links. The axles sticking out are IRL going to be filed down to be more flush. With these figured out, I have moved on to the rest of the needed items for the reciprocating engine. As mentioned above I have also at least some basics done on the turbine, including the rotor and its casing. Once its a little farther along Ill try and get some pictures up for folks. Any suggestions? Anything I'm missing or not figuring right? Please let me know!

Hey, welcome back Tommy! If you can't find them, that's perfectly fine, I can for the most part easily see what you've done.

Hey there Aero, Given the sizes we are working with, I think we can effectively hide the actual pneumatic pistons in the faux cylinders, without compromising on looks or workability. I have noticed the issues you mentioned in regards to necessary air pressure, though perhaps that can be solved with a little drilling out of the connections to be wider, and perhaps even getting a slightly larger diameter tubing, though again I'll hopefully be able to do some IRL testing to see what works best. On another note, we can similarly hide almost anything in the turbine structure given its size, though again all things working out I would like to see how close we can match the original system of air use where possible. Would anyone have suggestions on how that might best be designed? I would do similarly to many in using gears to act as the blades, but do we need any special housing around them to direct the air or just round the inside and perhaps use the negative pressure of the compressors to suck the air a particular way? I'll be working on some designs tonight, hopefully having some pictures to post within the next few days. Thanks again, everyone! I'll look forward to hearing more from you all! Reference Pictures:

In this case, I would be looking for something to replicate the image below: The necessity would be something that can connect up top to the valve rod, either using an axle or pin connection and from there I can use other means to get the off-position turning action working. However, if there was something that could work as intended for there to be a disc with a strap around it that can connect to something vertically, then all the better! As it stands, I would need to shave off a few millimeters from the train wheel I mentioned and chop off both ends of the cylinder with axle hole part to make it thin enough for my purposes. Again, I would preferably be looking for something no more than 2-3 plates wide to make it fit. Unfortunately for this the cam just doesn't work.

Alrighty, so realizing its been almost 2 years to the day, I am happy to say that I've been getting back to this project as of late, and have been better realizing both my limitations as well as improved possibilities that might make this project work. As such, let me get people's ideas on the following system: The idea is ultimately to get a somewhat self-sustaining system of thrust - no need for coal for this baby! The system will make the best use of pneumatics as possible, starting with the boilers being used as casing for custom air tanks, made from either plastic or aluminum bottles where the screw lids have had the pneumatic T piece added in. Multiple lines will then lead to the second part of the system: the Reciprocating engines. As historically, the lines will first go to the High-pressure piston, which then leads to the mid-pressure piston, and finally gets split off to the two low-pressure pistons. These will provide both realistic actions as well as rotational power to the outer props. The remaining pneumatic air along with an additional direct line from the pumps will then lead to the third part of the system: the turbine for the middle prop and condensers, the latter of which will hide some lovely compression pumps to both recompress the air from the turbine to refill the tanks in the boilers, as well as supply higher psi air to the electric generators. The generators would, in turn, recharge the chargeable lego batteries the air compression system uses, and perhaps and any excess power going to charging the batteries for lights in the ship. I have some pictures below of the models, though in Recip. Engines case incomplete. What I am mostly looking for is feedback on feasibility. I do not as of right now have the items necessary to test to see if this system actually works outside of theory - though I am working on that for some IRL practicality tests. For those of you that do have more practical knowledge already, please let me know! With just 1 XL motor, a youtube video I can link to showcases promising power generation capabilities that I think would ably at the very least power the air compressor batteries when 4 are being used, and maybe even power lights for an overall ship. However, by necessity, I might need a reality check on my plans, which I hope you all might best provide. Anyway, here are some pictures! (I realize that some parts aren't fully connected, particularly on the Stephenson linkages, but I can say that they are definitely in reach.) I do have one other request, that being if anyone knows of a good way to do eccentrics that are no more than 2-3 plates wide? That is the one thing that has been plaguing me the whole time that short of taking heavily modified versions of a train wheel (pt #85489b) and a ground down cylinder with axle holes (pt#2745), I'm afraid I'm at my wit's end. Let me know if any have possibilities. And Tommy, if you are still out and about, would you mind if I were to mostly use your designs above for the cylinders? Thanks everybody!

Hey there Tommy, Looking very nice indeed! Will be interesting to see what you intend for the connection between the bottom and cylinders. Again, I am really appreciating your time on the project.

Hey there Tommy, Those are looking excellent! I might have some concern regarding their structural integrity under pressure, but moreso about the lack of holes for piping in the air, though I saw you mention this was a rough draft. I've been trying to fiddle with more brick instead of plate-built ones for both of those reasons. And taking a peek at the cross section image above I provided, it might be difficult to proceed if we don't do something more brick built. But you should continue with what you have in mind and we will see where it goes!

Hey there Tommy, I am glad you have agreed to take this on with me! I greatly appreciate your help. I will be over with college classes next week, so I can certainly relate. But to answer you, we do want to avoid making the engines as a whole operating with an uneven width of bricks, as that will make everything else off. So if you orient your building with the LP cylinders being 10 bricks wide for the outside diameter, that would be ideal for everything else we would attempt to do. My guess would be that the other cylinder dimensions would be 8 for the IP and 6 for the IP. Also, the overall dimensions starting with the baseplate will be 22 in width, and give or take very close to 72 in length, and no more than 48 in height.

To continue the conversation perhaps with the danger of double posting, an idea to keep the air pressure in the cylinders comes from a comparatively simple possibility shown below: The piston shaft (grey) with the technic reinforcement goes through the 4x4 round plate with a hollow center (yellow), that provides a rather seamless portal for the piston to go through without allowing air back down in the traveling. The 4x4 square plate allows other plates - or more likely tiles - to be placed inside the cylinder again without allowing gaps for air. I am sure this has been done before or is a very elementary a concept, so forgive me if this seems like preaching to a very knowledgeable choir. I am still on the learning end, especially applying engineering principles to LEGO. Secondly, I found an excellent cross-section of a steam engine that can be indispensable for our own designing of the cylinders to be seen here: Let me know what you think. And one last thing to showcase, an attempt on the thrust block:

Hey Tommy, Now what would be the fun of the project without a little challenge, eh? As for the scaling, the ship as a whole is generally to the scale of the minifigs, and I would beware the danger of underestimating the sheer enormity of these beasties, they were each over three stories tall! But I would concede to dropping to something closer to 8 studs wide on the LPs, as the dimensions I gave are educated - but still rough - estimates. I did want to reiterate that this wouldn't be working off vacuum, was just using the video as an example of the mechanical possibilities. It would be using air power, which will be much quieter, and again you might be surprised at how powerful this setup can be if under load, though I don't have an exigent example to showcase. Ultimately, let us cross that bridge when we get to it. We can probably use an electric motor to help power the turning engine towards the rear that was the beginning impetus. We can also make use of some hidden gearboxes in the thrust blocks to help get more torque if need be. Lastly, this was an awesome engine with a lot of thought put into the design, including the angles at which the pistons rested on the crankshaft and the including of an additional LP cylinder to reduce vibrations in combination with the Piston angling. On another note, I doubt there will be too much problem with ducting air as the usual tubing can be hidden in brick-made larger tubes that better match the scale, or perhaps use those large tubes introduced in the Mission to Mars line. I'm liking the discussion, thanks for the help so far, let's keep it up!

Hey there Tommy, Thanks for getting back to me! I do hold out hope that this project is possible because of things like this by mechanicsnut on youtube, see here: I do realize that the ubiquitous use of vacuum power would be a much different beast than pneumatic power, but I am hoping that the design can be very similar. On another note, I might question the scale you are thinking on, though I didn't give the dimensions necessary for some of your calculations, so that is my fault. So let me fix that. Some of the dimensions we are working with are (including the base) about 22 studs wide, 72 studs long, and (give or take) 48 studs tall by my estimations using Ldraw's dimensions report, which measures height in the SNOT style. So with that in mind, the cylinders would be 10 studs wide in the largest cylinders, which is significantly more room than your original estimates. Secondly, to help with airtightness, I intend that while the outer shell is rounded, the inside should be squared off rather than be circular to aid in the ease of design. With all this in mind, I think we have some decent chances. What do you think?

Dear fellow LEGO enthusiasts, I am in dire need of some help from you folks who are definitely more knowledgeable than I. In this case, I am needing help with the replication of the RMS Titanic's Reciprocating Engines and Turbine. I am in the midst at the moment of working on the project below, though I have not updated it in a great while due to university work. See this link here for the project thread. But this is a minifig scale project, with every door, every window accounted for. This means that in regards to the engines, I am also seeking to make them at least somewhat true to scale and able to work as intended. Obviously this is a big job of some top notch Edwardian-era engineering, but I am hoping that there might be some out there not as technically-challenged (pun totally intended) as I am, willing to help me get this part of the project off the ground. Some of the features I I am looking for include a fully air-powered system, where the air supply would come from tanks hidden in the mock-boilers, that are then funneled at somewhat high pressure to the Triple Recip. Engines, which means that the pressure would go down as it goes through each cylinder (HP, IP, then two LPs). The leftover air at a much lower pressure then goes to a junction that can either go to the Parson's Turbine at what was historically 4 psi, or can go directly to the condensers. With the latter I intend just to make the outside of it and hide inside some custom compressors like this. That would then return to the original air supply. With this I am hoping that I will have a self-supplying system with ideally no more than 5% leakage, or enough compressors that leaks are compensated for. WIth the Parson's Turbine, that can be an accurate shell with whatever is needed inside to include a working turbine, and probably with an gearbox and ascending set of gear ratios to give it the necessary torque. These engines and turbine are meant to actually turn the propellers, perhaps even in water! Some other features would include a replica of the Brown-type reversing engine on the side of each of the Recip engines, making it so that the Stevenson-type eccentrics can change the direction of rotation. Considering the scale, the reversing engine doesn't technically have to be much more than a slightly-hidden piston that does the required job, but any more realism doesn't hurt. If something like this is possible, please let me know. I am really wanting to continue with this project, and this is a central part of it. But without the pieces in front of me instead of on a computer screen, what little I know of engineering definitely doesn't help without that tactile interaction. Thanks for your time, and I look forward to your replies! If it is possible, then I can follow up with the intended dimensions. Here are some references for any that wants some: View of turbine and condensers through wall from main engines rotor shaft model of port-side recip. engine overall basic view path of the steam of original, pressurized air for mine