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.