MLW RS-18 build

Stephane Savard Jul 5, 2021

  1. Stephane Savard

    Stephane Savard TrainBoard Member

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    I wasn't quite sure when I was going to start this project, but having solved some mechanism issues, with a day or so of vacation, cool weather, and fiddling with the 3D modeling software, and well, here we are :D

    When I first started in this nice hobby, I ended buying a KATO VIA rail passenger car set off eBay - the blue ones. Just seems like the right thing to buy at the time, but turns out it's completely wrong for the era I'm making my layout. My layout isn't prototypical, so in my world, a museum saved two of these coaches from being scrapped and runs then for tourists. Why not eh? :)

    So what locomotive to run this little train? I absolutely wanted a high hood nose locomotive, even if it doesn't fit my modern era, and it just so happens that RS-18s have actually pulled these blue coaches in the past! But there are no RS-18s in n-scale. Or well, there might have been once upon a time, one or two companies that produced shells that were used on Atlas RS-11 mechanisms. Now since I do own a 3D resin printer, and it's on my TODO list to make a locomotive shell, seems everything was in place to try this out!

    So first step, was to locate and buy an Atlas RS-11 - in this case, I lucked out and found a recent run of the model - a Toledo, Peoria and Western model that was last released in 2015 - DCC even! It took some time getting up here to Canada, and had a bit of trouble getting it running, but it now works absolutely great.

    So this will be my first locomotive shell that I 3D print, and well, in the past, my biggest projects so far have been an HO cattle car, and and the n-scale gondolas that where the subject of a previous thread on this sub-forum

    So what exactly do I model?

    Well, this proved to be a really easy choice. I live in the province of Quebec, and have visited Exporail, a local(ish) rail museum. There they have an RS-18, in Canadian National Railways colours. Not only that, but I found a website, Trainiax, run by someone here in Quebec that appears to make line drawings of locomotives as a hobby, and he's produced such a drawing for the Exporail's RS-18! (y)

    [​IMG]
    (image linked from http://www.railpictures.ca/?attachment_id=34896)


    MLW-RS-18-CN-class-MR-18c-phase-1b-sm.jpg

    (image by Trainiax - http://trainiax.net/medim-mlw-rs18.php)


    Armed with a bunch of drawings, a bunch of detail photos of pretty much every angle of the real locomotive, and more than a little hope, I launched Fusion 360 and started drawing!

    Baby steps, I need a replacement shell for the mechanism. That's where it all starts. Well, with no prior experience in this sort of thing, I figure that's likely my first step. I used the existing Atlas shell for the two most important measurements, the inner shell width and length. Everything will have to build from that, because anything smaller will just not fit the mechanism.

    In terms of the side view, I used Trainiax's drawings. I cannot be certain that his measurements are 100% correct, but I have to draw a line somewhere (no pun intended), so for all intents and purposes, I will consider his drawings as perfect and not look back.

    Head on and rear views of the locomotive, including dimensions are a problem though. Trainiax's drawings are strictly side view. So for those, I used the Atlas shell to determine the width of the hood and the sill.

    So where did this get me?

    rs-18-side-view-v1.png

    I started modeling exactly to the drawing, only making adjustments where necessary. For example, strictly speaking, the sill is thicker than in the drawing, but I don't have much of a choice if I want it to fit the mechanism (the Atlas sill is almost twice the thickness of the drawings - understandable considering we don't have all the under body details).

    rs-18-3d-view-v1.png

    Now, the point was to just make a box that would fit the mechanism. I just wanted to get the basic shape that would fit perfectly on the Atlas frame, and then see where to go with details. But as it is for my projects, I got carried away and did the hood curves and cab :whistle:

    The question you're probably not asking, but I will answer anyway - with only side views, how did I come up with the "correct" curves?? Well, I had to cheat, but I think I got it right. I looked online and found low quality head-on drawings of RS-11 and RS-18s paint schemes. The curvature on the hood and cab seemed to match, so I used the best one, added it to Fusion 360 and then did my best to match the same curve. Trainiax also does imply the curves on his side drawings, to which I did my best to match the model...

    rs-18-hood-detail-v1.png

    Now, I don't want to leave you all with just a bunch of drawings, did I get anywhere with this???

    IMG_20210705_170319330.JPG

    Yes! I did print a basic shell, and it mostly fits. In terms of width and length, the shell fits very snugly right over the frame, and the deck/sill covers the metal tabs on the bottom of the Atlas frame.

    IMG_20210705_182041646.JPG

    Now there are some improvements to be made for sure. First, the shell bulges out on both sides, and it took me a bit of time to figure out why. Looking at the frame, see that there are two dimples on each side? on the Atlas shell, these key into dimples in the inside of the shell. I'll need to do that too. I also printed the model flat, mostly as an experiment in supports (blades/skirts to reduce warping). While a mild success in some ways, it caused the expected problems in others (suction issues, and still a bit of warping post curing).

    Still, the basic shape is there! I still will revisit the curvature of the cab, it seems to be flatter than expected on top. Also, the curve of the hood where it changes from vertical to mostly horizontal doesn't look quite right compared to photos - too sharp.

    I'm also wondering if I should try to print this in two pieces - hood + deck, or keep it in the single part seen here. This is where my lack of experience is showing.

    I still need to measure the height of the hood from the rails. In terms of the drawing (deck to top of hood), it's correct. But the lightbulb "bottoms" out in the short hood section causing the DCC board to bend a bit. The Atlas shell has a slightly taller hood. I'm fully aware that sometimes you just have to make sacrifices to realism to fit the scale.

    Anyway, this has been waaay too long already. Very sorry for the long post, I do tend to ramble on :ROFLMAO:

    I hope you like - like my previous Gondola build, this is going to be a journey into 3D printing with a newbie, warts and all! :D
     
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  2. CSX Robert

    CSX Robert TrainBoard Member

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    Looking good!
     
  3. SLSF Freak

    SLSF Freak Staff Member TrainBoard Supporter

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    This will be fun to watch evolve. Looks like you're off to a good start!

    Mike
     
  4. Sumner

    Sumner TrainBoard Member

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    You are off to a great start. I'll be following this but I don't think I'll be trying it myself. Also thanks for the introduction to http://trainiax.net/. What a great site and resource. Unbelievable the number of drawings there,

    Sumner
     
  5. Stephane Savard

    Stephane Savard TrainBoard Member

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    Life's been getting in the way, so progress was almost non-existent for a couple weeks. But now I'm on vacation for the next three weeks! :ROFLMAO:

    The only thing I have to show is an update on my progress on the 3D file...

    rs-18-3d-view-v3.png

    I'm getting very close to the point where I'll be printing my second prototype, to see if everything, well, prints. I'm really hoping that some of these details will be candidate for the "There's NO way that's going to 3D print!" thread :D

    I have struggled on the "head-on" details (though on this particular model, the short hood is actually the rear). I'm fairly confident that any of the side details are good (i.e. length and positioning of the cab, of the side windows, the height of the numberboards, pilot etc. Like I've previously said, I have amazingly detailed side views. But my head-on views are terrible!

    Take the number boards for example. I have no idea what angle they should be at. I have about 36 detail photos RS-18 number 3684, but of course, these are all taken from the ground, and have distortion based on the camera lens perspective. So I try as much as I can to match the photos by placing the parts relative to other parts. Curves are also very difficult to judge, but these look fairly good.

    Another part where I spent literal hours on was the stairs leading up to the deck. I have no measurements, so I had to base the depth of each stair based on the photos. Not easy when the stairs are painted black, and taken indoors in low light levels!!! How did I finally get to this iteration? I noticed that the pilot photos show the bolts for each stair, so using a front view of the locomotives and relative pixel distances I came up with what is likely a good representation.

    Anyway, I have a few more details I want to add, and I then should be attempting to produce a printed prototype shell. Again, not all the details will be in the print, but more of a sanity check to make sure what details I do have print, the coupler fits, and the parts aren't too flimsy!

    Hopefully the next update won't be in a couple weeks.
     
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  6. SLSF Freak

    SLSF Freak Staff Member TrainBoard Supporter

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    Well - just know that everything you're going through is on point! (y) It's hard to do it right when you don't have a blueprint in front of you or you can't fly a representative out to a museum loco to take measurements. But what you're doing is exactly what I do: grab as many reference photos as you can, mock it up then start shifting shapes to get closer and closer until you can't find anything wrong with your model. You eventually get into this mode where everything becomes a "reference" whether it's the shape of the inward panel of your forward light boards (square or rectangle?) to the relative positioning of the edges with respect to the bolts on the headlight housing, or with respect to other areas louvers, hatches or whatever. After it looks perfect, then you may have other things to contend with - in my case I've had several models that were difficult to get truck swivel clearance due to steps being in the way of the trucks. Or how to slip a unique fuel tank cover over a chassis that has a big hunk of metal in the way (if you're not inclined to mill the frame) So then it's back to the drawing board to figure out how to remedy all that while staying faithful to the design. All that said, the end result is so worth it when you've got something that is unique to the hobby that materialized from your brain to a physical object running around the layout. Keep up the good work!!

    -Mike
     
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  7. Sumner

    Sumner TrainBoard Member

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    What a great job you are doing. I have a feeling that many of us just don't realize the hours that can go into these design projects. Having a CAD program and know how to use some of the features is just the first part of the curve.

    I Googled 'RS-18 number 3684' and found a number of links to the loco that I'm assuming you have seen also ( https://www.google.com/search?q=RS-...rome..69i57.3058j0j7&sourceid=chrome&ie=UTF-8 )

    [​IMG]

    The one above is pretty good on the back view and they have a frontal view and a few others (in larger formats than the picture above). To me it looks like you've got it pretty darn good. If you know the size of the lights between the number boards that might give you a pretty close distance of how far they stick out by the lights but you look very close to what I'm seeing above. I found that and other pictures here in case you don't have that link....

    http://www.rrpicturearchives.net/locopicture.aspx?id=74537

    ....also what goes with the different paint jobs shown for the same numbered loco. Did they change paint schemes while it was active?

    Sumner
     
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  8. Stephane Savard

    Stephane Savard TrainBoard Member

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    weeeell, the museum where #3684 is located is, according to Google, just 33 minutes away :whistle:

    Though I'm pretty sure they won't want me walking all over their locomotive, heh. I went to this museum a few years ago when they had a model railroad day; it's a beautiful place! So far, I already have all the pictures I really need (http://trainiax.net/mephotosearchresults.php?p_type=MLW,RS-18 has 43 pictures of the museum locomotive, all large). I'm not sure my visiting the museum will result in much better information, though I may go take a look when I'm further into the project, maybe to answer my last questions and make the final adjustments. The link to the pictures I posted above are from the same guy that made the side view drawings and what I'm using for the measurements.

    Anyway, thank you Mike for the encouragement, you've helped me along quite a bit! I totally get your comment where everything is a reference to everything else. The other bit that's difficult is that I have to keep making adjustments that will actually print. Take the pilot's back plate, at the edges - if I printed the thickness to scale, it would be less than 0.1mm thick! So I thickened it up to 0.4mm for my first test. But by doing that, a whole mess of other measurements are affected! That and I'm convinced that the Atlas model's hood is wider than it's real size counterpart to accommodate the mechanism. So everything I do needs some adjustment based on that. I do take a look at other models (commercial and not), and see how others have dealt with these issues. For my first test, I'm going with flimsier thicknesses that are closer to scale, and after a test print, I'll adjust as needed, to make sure I have a model that's useable.

    You know, so many times I wonder if a detail I'm working will even print. I think I really should make myself a test object where I print raised panel edges and bevels at different thicknesses and height, same with rods and rivets, printed on vertical, horizontal and slanted surfaces. That way I could better judge if something will print when I'm designing.

    Sumner, thank you for the links - I think I've already seen and downloaded most of the 3684 photos (including rrpicturesarchives.net and railpictures.ca).

    The picture above was probably when it was on the active roster - I do know that when the Exporail museum got the 3684, they repainted it to its original factory green scheme. I think that's the scheme I will use, especially since on my last trip to the local hobby shop, I found and bought the Microscale decal sheet (87-948) for the green scheme RS-18! Though I'm really puzzled as to how It's be able to apply the top of the nose yellow decal with the headlight and numberboards molded into the body.. hmm.

    I'm really glad that people are enjoying this, I'm having a lot of fun, and that's all that matters (yup, for me, fun & enjoyment > perfectly scale)
     
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  9. Sumner

    Sumner TrainBoard Member

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    I did that to some degree to see what I could get away with using the Ender 3 Pro FDM printer and will probably do the same when I finally start using the resin printer. It is sitting there patiently wait on me. Really busy with some other projects so probably won't be used until fall or so,

    Sumner
     
  10. CSX Robert

    CSX Robert TrainBoard Member

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    This may vary depending on the slicing software, and there may be a setting somewhere that affects it, but at least with my current setup the slicing software will not print anything less than 0.42mm, even though the printer has a 0.4mm nozzle.

    Most slicing software packages have a "layers" view that will show if the printer will even try to print a particular detail.
     
  11. Mike VE2TRV

    Mike VE2TRV TrainBoard Member

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    CN 3684 was built in the 1950s, delivered in the green and yellow freight scheme. Then it received the 1961 image, black with red ends and the big CN noodle on the side. After 1973, the zebra stripes were the in thing. 3684 is now proudly displayed at Exporail (33 minutes from St├ęphane's location), resplendent in her original 1950s colors.

    She's also in operating condition! Nothing sounds like a 251 gurgling merrily along.:)
     
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  12. Stephane Savard

    Stephane Savard TrainBoard Member

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    CSX Robert; I'm printing using a Resin printer, 0.4mm can be printed without any problems, but may be too flimsy. It really depends on a size of the area.


    I think my model is ready for the prototype print, and I'm currently printing a RERF test with a new resin! I ran out of my "preferred" resin - the Phrozen Rapid Black water washable. This was the resin I used for the gondola I last printed. But, really, instead of going out and buying some more, I figured it was smarter to try the a bottle of resin I bought months and months ago but never tried. I've loaded up the vat with some Siraya Tech Blu v2 clear. This thing is pretty thick, much more than other resins so far. Also likes to be printed at 30 degrees Celsius, so I preheated by resting the closed resin bottle in hot water, and even pre-heated the resin in the vat with a hairdryer. I'm really curious to see the RERF test in about an hour or so.
     
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  13. Stephane Savard

    Stephane Savard TrainBoard Member

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    So, turns out the print took 3 hours and 25 minutes to complete!

    IMG_20210803_084831215.JPG

    Here it is, straight out of the printer, after the first wash. While on the build plate, this resin was perfectly clear, if a bit yellow. Washing the print caused it to go from clear to milky. The auto white balance on my cell phone here is really struggling, and rendered it much more yellow than in person - I couldn't be bothered to go into manual settings to correct it.

    I may have gone a bit overboard with the supports, but it came out well, so that's fine. I've heard from different people that print commercially that they like doing their own supports right in the modeling software. I did give it a go, but it was taking me absolutely forever, and I couldn't figure out how to put in the diagonals for extra stiffness. It would be nice to see someone make a video or thread how-to about that! :D

    IMG_20210803_091057711.JPG

    Here we are, supports are removed, and post cure is complete! This resin (Siraya Tech Blu v2 Clear) is a chore to clean well!!! The resin is rather thick, and it sticks very very well to everything. 99% alcohol barely seems to dissolve it, so it took quite a bit of scrubbing with a soft bristled paint brush to get it real clean. Siraya Tech recommends using Ethanol to clean the prints, but I don't have any of that (and as far as I can tell, isn't available at any hardware store in Canada). Still, I did manage to get it cleaned, and I post-cured the shell in water.

    If you look at the sill, it looks like it's warped...

    IMG_20210803_091135374.JPG

    ... and well, it is! The long hood is splayed outwards, so that will be my first fix. In the next print, I will put in an internal support structure to hold the hood together during post-curing. I can then remove the supports and the result should fix the warping. I could maybe even try heating up the shell in hot water and and seeing if I can put it back into place - this shell is a throwaway prototype, so why not? no harm if I break it.

    One thing I noticed however is how little bloating we're seeing on the underside of the print! There is virtually zero bloating on the underside!! :eek: This is only my first print with this resin, but I'm very curious to see how it keeps performing.

    IMG_20210803_091340474.JPG

    The cell phone isn't great at macro, but it's passable. The stairs and pilot came out very well! All the thicknesses seem to be spot on, except maybe for the platforms at the bottom of the pilot. I think those were printed to 0.35mm and I will likely thicken them up a bit more. They did warp slightly upwards, though maybe that doesn't matter in the end. I've seen several RS-11 and RS-18 in photos where the pilot and platforms are bend out of shape. Even on #3684, the middle slanted part is heavily dented inwards!

    One negative about using these clear resins is that it's very difficult to view details until the parts have a coat of primer on. I which they had this is smoky black instead of perfectly clear.

    IMG_20210803_092003612.JPG

    The shell fits the mechanism! well, mostly. See that circle just behind the cab, errr, to the left of the cab? ( I don't know I keep taking pictures with the long hood towards the back :whistle:). Well, that's a dimple inside the shell made to fit protruding dots on the mechanism (two on each side). The dimples on the long hood fit correctly, but the dimples on the short hood are a little too high. An easy fix for the next version.

    And finally, the last test I wanted to check was the coupler!

    IMG_20210803_093626128.JPG

    I'm using the couplers that came with the Atlas shell, and the fit is very tight. I had to sand the coupler pocket a little to get it to fit. I can already see that I can push in the coupler into the body a bit more. All I need to do is move the bolt hole on the model further back, not by a lot, maybe only 0.2 mm.

    IMG_20210803_093505423.JPG

    However this I need to fix! The coupler is too low, but not by much. The only thing I'm not sure about is whether the end of the deck warped down a bit. I 'll have to install the second coupler and see how that fits. Also, the other thing that bugs me a little is the height of the pilot off the ground. It looks like the shell may be sitting on the mechanism a little too low, but the deck height is actually equal to the Atlas shell. I think the Atlas shell's stairs and pilot are actually shortened.

    rs-18-pilot-detail-v1.png
    I mean, my model is as close to the side views I'm using as I can possibly make them! As seen in the picture above, the sill is actually thicker than the real thing, but I need that thickness to allow the sill to hide the metal tabs on the atlas mechanism (my sill is the same thickness as the Atlas sill).

    I'll very likely ignore this if my shell can run throughout the layout without the pilot hitting the rails. I do have some nasty grades on my little layout, so that could happen. Next I'll install the second coupler, and try running everything as is around the track, make sure the clearances are good.

    Anyway, that's it for now!
     
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  14. JMaurer1

    JMaurer1 TrainBoard Member

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    Ethanol is also (mostly) used as a antiseptic and as fuel (racing fuel). Try the pharmacy or local drag strip. Ethanol is also used as a cooking fuel and rocket fuel.
     
  15. Stephane Savard

    Stephane Savard TrainBoard Member

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    Thanks JMaurer1, but 99% IPA works, just slow, I don't want (yet another) chemical in the garage!

    Ok, so quick update, I attached the second coupler and then realised that the height is perfect. The first coupler had not been screwed in all the way, and I think when I sanded the pocket to make it fit, I ended up sanding at a slight angle. But it fits quite nice now! I also used a dremel to fix the dimple, it'll help me figure out how to adjust the model's
    dimple in fusion 360.

    IMG_20210803_112611355.JPG

    Finally, took a small video; the height of the pilot is not a problem and will stay as is - no catching on the rails anywhere, even on the worst of the grade changes...



    I still have a problem with the mechanism though. Whenever the engine is running on straight track, it's quiet. But enter a curve, and there's this buzzing noise. I had created another thread a while back, and never got to the bottom of this issue. Actually, I did pull out the truck and put it in backwards at one point, and the noise at the time seemed to be a lot less pronounced (almost fixed). But after adding and removing the shell a few times, well, the noise is back in full force. I'm not an expert at all, but it almost seems like the gear that is meshing with the worm gear is touching something up in the body.

    Maybe it's because this engine still hasn't been "broken in"? Hopefully someday I figure this out, but for now, time to start detailing this shell! :D
     
  16. Sumner

    Sumner TrainBoard Member

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    I do not think you could ask for anything more out of the first print. Outstanding design and work,

    Sumner
     
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  17. SLSF Freak

    SLSF Freak Staff Member TrainBoard Supporter

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    Just...awesome! If it helps, when I go through iterations of design I keep a can of Krylon all-in-one white (satin finish, in this case) in the garage to give my prototype prints a few light, quick blasts of "color" so I can see the details better. It's cheap, quick, dries relatively quickly and no clean up. I have a hard time seeing details even with the grey resins.

    Looking forward to your next update! -Mike
     
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  18. Stephane Savard

    Stephane Savard TrainBoard Member

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    Thanks Mike! You've been a lot of help so far, just your comment about printing flat and in one piece has so far helped me get this first great print. I'll see what I have in my rattle cans, I might have something to see that detail.
     
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  19. Stephane Savard

    Stephane Savard TrainBoard Member

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    I'm still around! Sorry for the lack of updates!

    First vacation, then kids back in school, and well, I've got a lot less done in my train world than I wish I had done. But I'm still slowly working with the 3D model, and this past week's been seeing most of the roof details added, as well as some of the front and rear details. Not sure what details will print yet (looking at you radiator grill and rings!), and some details need to be adjusted still.

    rs-18-3d-view-v4.png

    Only a 3D render for now, nothing sent to the printer just yet. That roof top is really difficult, which is why I started with it. I have zero photos of the roof taken from the air. Every single shot I have are from ground level! So, I've been looking at RS-11 shots, and other RS-18 shots, but very very very few of them have either clear shots, or close-up shots. If they happen to be clear, then it's usually of a different variant that's no help to me. There's been a massive amount of variations on the different panels, ports and doodads up on that hood, making even more difficult to figure out what it really should look like up there. I do know the exhaust stack needs to change, almost certain it should look different. Still, except for some weird flat antenna on the cab and then the horn, the top is "done" for now. And that horn will likely be printed separately for better orientation. Seriously looking forward to working on the sides - I have a heck of a lot of photos for that at least!
     
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