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Thread: QTTX131600 Build Thread

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    Default QTTX131600 Build Thread

    Although I don't have much rolling stock yet (I'm perilously close to a 1:1 Locomotive to Rolling Stock ratio), I've been drawn to heavy/dimensional loads. Possibly because my Dad has worked on pressure vessels for the oil&gas industry, which involved some pretty massive moves after they were built (albeit mostly by road, with 100+ wheel trailers) In particular, the heavy duty flats in this video caught my eye: https://www.youtube.com/watch?v=ySOZfQbcllc

    After some digging around, I found lots of information on the QTTX131600 series heavy duty flats. So, I decided to try and make my own. It might end up being a long term project, but I thought I'd share my progress on here. The current plan is to have it 3D printed.

    Lots of photos:

    http://www.solrswat.ca/1%20Equipment...600-131624.htm

    Line drawing (miss-labeled on the page, made it really hard to find!)
    http://www.solrswat.ca/1%20Equipment...QTTX131626.htm

    A few photos in CN's Dimensional Load brochure, including some really cool bolster-loads across two flat! (See Page 4. That's something I really want to try to make!)
    http://www.cn.ca/-/media/Files/Custo...y-Loads-en.pdf

    I'm part way through my latest iteration of building up a 3D CAD model right now (wasn't happy with the first tries) that I'm finally happy with. One of the trickiest parts has proven to be the buckeye trucks, as they're somewhat unique, and due to the very small dimensions in N-scale, the existing microtrains buckeye trucks won't quite work, as they would cause the entire model to ride un-prototypically high. As such, I took it upon myself to model my own trucks, based off of whatever photos I could scrounge up and some drawings of similar (but not identical!) buckeye trucks.

    Here's what I've got so far for the buckeye truck. Some details aren't 100% prototypical either for manufacturability, to exaggerate some features so they actually show up after 3D printing, or because I kind of like how those features turned out. Either way, the things going to be so small once it's printed, that a lot of that will be too small to see anyways!
    QTTX131600 _ BuckeyeTruck.jpg

    There's still some work to do on fixing details to make them more accurate, as well as re-designing my method of mounting the trucks to the bolsters (Currently it's assuming bolster-pins through the bottom, but there's so little clearance that I'm not too happy about it)

    I have the center span and deck modeled, and need to re-start the bolsters and end-decks. Once I have something resembling the full car that I'm happy with, I'll post photos of the rest -- i'm just particularly proud of this truck, as it was a pain to get looking somewhat realistic.

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    Quote Originally Posted by roko View Post
    I'm perilously close to a 1:1 Locomotive
    I read that wrong the first time. I thought you started to say you have a prototype locomotive and flatcar (1:1 scale). Very cool project though!
    Bronman - "Trains and Legos... you can't have too many of them."
    My Layout Build Thread - The Spokane & Eastern Washington

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    Quote Originally Posted by Bronman View Post
    I read that wrong the first time. I thought you started to say you have a prototype locomotive and flatcar (1:1 scale). Very cool project though!
    The 1:1 GEVO is after I win the lottery :-D

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    I'd be interested in the roller bearing equipped buckeyes, def a truck needed in N.

    Curious if you have looked into N Scale Kits, they do a lot of heavy duty TTX cars

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    Here's where I'm at:
    qttx131600-overview1.jpeg

    There is still some detailing left, as well as double checking everything fits together. I'm designing for an 11" radius maximum curve, so in some locations I had to deviate from the prototype line drawings to allow for extra clearance of the trucks as they move around. The image above depicts what it would look like going around the max curve.
    Attached Images Attached Images

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    That looks amazing. Props to you.
    Daniel Dawson

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    wow roko!!!, would you ever consider designing some of the larger KRL depressed centers? http://southern.railfan.net/flat/car.../krl16450d.jpg

    I too am interested in the roller bearing buckeye's
    Last edited by 24zer0; 16th Feb 2016 at 09:31 PM.

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    How do you plan on weighing this car down? A 3D printed flatcar will not handle well without some serious underside metal.
    Karl

    CEO of the Skally Line, an Eastern MN Shortline

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    Thanks for the compliments everyone!

    Quote Originally Posted by jpwisc View Post
    How do you plan on weighing this car down? A 3D printed flatcar will not handle well without some serious underside metal.
    Good question, and one I probably haven't put enough thought into... I'm trying to make as many hollow spaces as I can, so there is some internal volume there that I can fill up with something (Cut steel sheet, molded lead or tungsten powder capped with epoxy?) Those spaces are fairly small, so I'm not sure how much I'll gain. I'll have to calculate how much volume I have to play with. Worst case I suppose I can compensate with a bottom-heavy load.

    I'll dig through some of the old threads on the forums WRT weighting, and am definitely open to suggestions.

    Quote Originally Posted by 24zer0 View Post
    would you ever consider designing some of the larger KRL depressed centers?
    Let's see if I can get this one to work first... I fear I might be pushing some boundaries with the details I want to print. :-)

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    Getting closer to being ready to 3D print the model. I've added/tweaked some details, especially on the trucks. Still not 100% prototypical with some exaggerated features, but I'm hoping they will turn out nice when printed.

    QTTX131600 Detail2.jpg

    In the picture below, I have all the parts arranged for printing. -- I've uploaded this to Shapeways, and according to the automatic checks, it's printable. Hopefully it actually works out!
    I still have still some more checking of clearances to do before I send the order out. Hopefully I'll have time for that this weekend.

    QTTX131600 Parts For Print.jpg

    The blue cylinders under the chassis are some of the larger bolster-pins for pinning the bolsters to the main span (with extras). I've also designed those connections to fit wafer-head screws so I can experiment with both ideas.

    One detail not shown, is that I made pockets for three small magnets to sit under the deck. I can use those magnets to easily affix and remove loads.

    Some rough mass estimates...

    Plastic mass: ~6 grams
    Wheel mass 12 x ~0.75g -> ~9 grams (based off measuring a single metal wheel -- So not very accurate. I'll need to measure more wheels at the same time to get a better estimate)
    -----
    = 15 grams approximate weight for the car plus wheels.

    I've got about 0.3 cubic centimeters of easily accessible extra internal space, if I filled that with tungsten powder I could get maybe another 3 grams.. not much.

    Another option is printing the bolsters out of metal. I might get about 1 cubic centimeter of volume (An estimate. I'd have to re-design without some cutouts to maximize volume), which could be an extra 8 or so grams for both. Still shy of the NMRA recommendation..

    Alternatively, It may make things interesting by adding the operations element to running this car -- With a weighted load being one dynamic, and the un-weighted car being a different dynamic. We'll see how it plays out. I'd be happy just running with weighted loads.

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    Should definitely consider making the trucks separate sale items as well... Alot of the DOD flats I've seen use those trucks...
    :SFSD75M::SPWELL::TTX::SPWELL:


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    Minor update... I've spent some time trying to catch anything that might be an issue for 3D printing, assembly and operations. I also whipped up a quick load, just for the heck of it, loosely inspired by the one in the video I linked to in my first post. It's hollow, with the light-blue piece being a thin small plug. I might try and make this modular so that I can use the big grey part as an "end piece", and add a centrer section between two end-pieces to make a longer load that bolsters between two flats.

    But first, I have to see if any of this even works when printed -- I'm going to probably order this a bit later on today, along with plenty of wheels and couplers. After ordering, I'll switch to thinking about decals/numbering....

    WithLoad.jpg

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    One small suggestion I might make for 3D printing is to align your bolster pins so their axes are vertical. I would think that it would be better not to have the slight roughness from the layered printing process be on the surface that you want to rotate freely and they're small enough that it's not going t affect the volume much to do so.

    A very cool project!

    Linux Punk

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    Great point -- This one's already at the 3D printers so can't change it now. From my understanding, however, Shapeways can't guarantee orientation anyways, so perhaps it would be all for naught.

    As an update, I sent the order in on Sunday. Fingers crossed that the printing actually works.

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    A nice little package was waiting for me when I got home from work today, and I couldn't resist throwing it together (The girlfriend wasn't home to stop me and make me do silly things like eat dinner first.)

    20160314_174541.jpg

    All in all, not too bad! The wheels don't spin quite as freely as I hoped, but that might be because of residual wax gumming things up. The bolster pins work amazingly well. The details actually printed, including the miniature handbrake lever!

    I need to trim up the screws for the couplers to the correct size (The MTL couplers come with VERY long screws...), then hopefully I can pull it around!

    Now, I need to figure out some dinner and other grown up responsibilities, but I'll post some more detail pictures later....

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    Okay, some more pictures and comments. It's running around my loop right now with 6 cars behind it

    20160314_171812.jpg
    All the parts lined up. I was impressed with how the details worked out, especially the thin wire features on the end platforms, the ladders and the handbrake. Shapeways really does a good job in FUD. This was actually my first model printed in FUD, so I wasn't sure what I was going to get.

    20160314_173148.jpg
    First two trucks and bolster assembled. Things came together nicely. The bolster pins fit well. I tried to make it a prototypical height, so there's not a huge amount of clearance for the center wheels on account of how low I had to make the mounting point. The wheels need to go in a very specific way, but do fit in the end.

    20160314_180022.jpg
    Side view of everything put together, minus the load. My favourite locomotive in the background.

    20160314_180031.jpg
    Top view. This is a 348mm radius track (13.7"). I tried to design it to clear turns on an 11" radius, but don't have any 11" radius track to try it out on yet.

    The honeycomb pattern is actually the support structure underneath the deck to keep the 3D printing volume down, and won't be visible when painted. The lashing holes on the edges are based off the positions in the drawing in my first post, and came out nicely.

    The three circles in the centerline of the deck are actually tiny magnets that fit into little round pockets. The load supports have corresponding slots to fit magnets into.

    The entire car weighs 16.1 grams with couplers, wheels and magnets. Pretty light! The load brings it to about 21 grams. There's some hollow space I can add some weights into, especially the load -- Perhaps a top heavy load adds to the operating dynamic of the car with regards to speed through curves. I limit my top speeds on my DCC decoders to scale speeds for the locos, so they won't corner super fast anyway

    As is, it runs well in my initial tests. I've got 5 hoppers and a "heavyweight" (but actually a Microtrains car so not really heavy) passenger car attached to it, and it's running well. I still need to clean up the left-over wax since I think it's effecting things a bit, but all in all I'm very pleased.

    Right now, it's all held together by the registration pins I put into all the parts, nothing glued yet. It'll be easy to take it apart again to clean up, but first I have to see what will do a good job of cleaning everything off (I don't want to jump to bestine yet, but acknowledge that it's what I might have to do in the end)

    Next steps are to paint it -- but unfortunately I don't have an airbrush yet so painting will have to wait a little while until I can pick one up along with some paint. (Luckily, I have a bunch of scuba tanks kicking around that usually have some gas in them, so won't need to buy a compressor )
    Attached Images Attached Images

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    One more shot I forgot to include in the last post, some of the smallest details....

    20160314_181053.jpg

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    Nice bearing caps.

    I'd like to see the trucks available separately. What axle length wheels are these designed for?

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    I'm nominally designing for .540 axle length, and testing with Athearn wheels advertised as .5445 but measuring approx .540. I think +/- 4 thou (.1 mm) is the tolerance in this material from shapeways anyways.

    I can put the trucks up separately, but would have to modify them -- these have a very low profile mounting point in order to fit under this particular flat. It's an easy modification, though.

    I'm going to make some tweaks to this design to get the wheels to run more freely, plus some stability tweaks for this particular flat car. Hoping to send those to the printer in the next few days when I get enough free time to fix things up. I'm still going to paint/run this one, but I think I can make it a touch better.

    EDIT: I measured some more of the Athearn wheels. Looks like they range between .540 and .544.
    Last edited by roko; 17th Mar 2016 at 12:21 AM. Reason: Hard to write well on my phone...

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    As mentioned in another thread, I got an airbrush this week, so with a small amount of free time I have today I gave it it's first hit of paint this morning

    20160319_091558.jpg

    The prototype trucks are pretty light grey in colour (with rust over that...), so I'm aiming for the light colour. This might have come out a touch too light, so I may darken them up a bit. I'm also thinking of doing at least a dark wash on these later, and perhaps play around with adding some grunge.

    Part way through painting the yellow now.. Opting for many light coats to cover it.

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