Modern 52' Gondola with fiberglass cover

Stephane Savard Jan 12, 2021

  1. mah2219

    mah2219 New Member

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    Good information Stephane. I haven't used a water washable resin. I'm surprised by the shrinkage difference. I've always wondered if color differences have any impact as well. I've only printed with Siraya grey or white in my Epax printer. I have an Anycubic photon also and only use Anycubic clear resin with smaller prints.

    Mike
     
  2. Stephane Savard

    Stephane Savard TrainBoard Member

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    It would be nice to know which resins shrink, and which resins are less likely to break, but it always seems to be impossible to find out before buying. I like the idea of a spreadsheet, but I don't know. I look at the spreadsheet for resin cure times and I was always skeptical due to seeing things like one person reporting a vastly different time than anyone else. If we did create a 5x5x100 bar for example, it would also need to be on supports. Notice how the supports coming off the raft in one of my picture were all sloping inwards to the shrunken part above.

    So far the only resins I've tried since I started 3d printing are Anycubic Green Translucent (1.5L), Anycubic Grey Opaque (1L), Siraya Tech Fast Grey (2L), and now the Phrozen Water Washable Rapid Black. In my cupboard I still have Siraya Tech Blu Clear v2 and Eryone Water Washable Blue that have yet to be opened. heh, I guess in total I've not actually printed any more than 4-5 L of resin across the Photon and the Mono X :D

    I can't say much about shrinkage, but so far Anycubic Green was the most detailed and the less likely to bloat on the underside (facing build plate), but very fragile (glass-like!). Siraya Tech Fast is by far the strongest (can bend quite a ways before snapping), but bloats terribly on anything facing the build plate.

    Anyhow! So yesterday I spent the evening running an exposure test on the Siraya Tech Fast, this time using the Ameralabs Town model. It was much easier to read the test, and yep, I was overexposing my print by a lot. So right now I'm reprinting the same Gondola print again (with a very slight adjustment to supports to try and save the stirrups). This time at 1.6 seconds per layer instead of 2.4 seconds. I'll repost the measurements of the gondola with this better exposure.

    I'm also preparing for the next test. I really would rather print the model with the floor in place if possible. So I'm going to try a print with the gondola rotated about 30 degrees, at 0.03 mm layer height. So that I don't need holes in the floor, I will print it upright.

    Now, if it turns out that the best way is to print the floor separately, then I think I may print the main body upside down, and sand the lip smooth and flat to get rid of the support marks. Of course that means I'll loose the little corner teardrop details I added to the top of the lip (can see it in some of the previous pictures). Sanding the top is so much easier than sanding the edge of the skirt! Anyway, we'll see after this test.
     
  3. Joe D'Amato

    Joe D'Amato TrainBoard Member

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    the upward bend is a problem on all these liquid poly printers. I have the Formlabs 2, Photon S and a Peopoly Mega and they all do the same thing. I got around it by adding n extension, like an extra long lip to the downward side of the part so the trailing off happens down there. You can also design the part to compensate if you have something other than Tinkercad...I tried that on an ho SP Copper consentrate hopper and it seemed to work well.

    Joe




     
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  4. Stephane Savard

    Stephane Savard TrainBoard Member

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    Joe, that's an interesting workaround.. would you have any pictures or screenshot showing this extension?
     
  5. SLSF Freak

    SLSF Freak Staff Member TrainBoard Supporter

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    I'm not sure if this is what you meant, but I did try this pre-bent caboose floor in the spirit of trying anything, and to my surprise it worked beautifully. I'd use it if I had absolutely no other way to counter the effect because it adds a layer of complexity to the design phase I could live without..lol
    preBent.jpg

    Another experiment I've been trying is to counter the amount of resin volume on the underside of the floor, with an equal volume of resin on the top side thinking the shrinkage of both would cancel each other out. That didn't work, but I think there are some additional tweaks to that idea I can try before writing it off completely. Also, really beefing up those supports does help*, and placing supports in a way that counter/pull opposite of the shrink direction (thinking more of the lateral shrinkage issues.) And lastly, I've been having success with hot/near boiling water to make the part pliable, over bending it in the opposite direction of the undesired bend, then locking the shape in with cold water. Locking it in straight only works temporarily so you have to lock it bent the other way so when it springs back it settles straight.

    I'm also interested in seeing a pic of the extra long lip method you mention, Joe. It sounds interesting and I'm open to all ideas!

    Mike
     
  6. Stephane Savard

    Stephane Savard TrainBoard Member

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    Bah, no pictures, but my last test at 1.6 sec exposure didn't work. It was actually clearly underexposed! But close.

    I'm testing something new today. The print where I did both a right side up and upside down at the same time was bugging me. See, on the print, the deformation happened on the side closest to the plate. So on one body, the skirt was shorter, and on the other the lip.

    Now yesterday I noticed something. When the print starts, the resin is probably at about 19 degrees Celsius. When it ends, much warmer. The coldest part of the print is nearest the plate, where it deforms the most.

    So today, I started a new print with adjusted exposure (1.8 sec). However, I put the resin vat on a lizard heat pad for a while, heating up the resin to about 25-26 degrees, measured with a non contact thermometer. When the print ended, I immediately measured the resin in the vat... 26.7 degrees.

    I ran out of time for tonight though, so will only examine the print tomorrow.. cliff hanger! :D
     
  7. Stephane Savard

    Stephane Savard TrainBoard Member

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    Inconclusive. I think pre-heating the resin may have helped a little. But I also had support failures due to Chitubox. See, so as to not lose the time spent placing the supports manually, I saved a Chitubox "project" file. However I noticed that after reopening the project and messing around with the supports a second time, it does weird things. I'm not sure that the state of the project is saved entirely correctly.

    The increased exposure to 1.8 seconds helps a little, but I still broke the bottom rung off some of the ladders. Siraya Tech fast is incredibly fragile before final UV curing, especially for thin parts. Those rungs are only 0.35 mm, and with 1.8 second exposure, they actually end up being .35mm, with the strength of a wet noodle.

    IMG_20210122_183753441.JPG

    There is a slight deformation, but at this point I'd be fine with it. The brake platform is bent, but that was my fault, I should have straightened it before curing.

    IMG_20210122_183811571.JPG

    For comparison, the latest Siraya Tech Fast print at 1.8 secs, versus the last Phrozen resin print. Really, I don't think I will buy another bottle of the Siraya Tech Fast. It just does not print details as well as other resins. See how the underside of the lip is bloated in the grey print vs the black. Same for the area between the bottom rib and the brake platform. It's a shame that the Phrozen resin shrinks so much!

    Enough for now, I'll think about what to try next. Probably a 45 degree print, upside down with vent hole.
     
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  8. Stephane Savard

    Stephane Savard TrainBoard Member

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    Alright! so here's the next installment of the gondola print. This one actually made it to paint. :ROFLMAO:

    So For this print, I decided to print upside down, at a 45 degree angle, and I made sure to heat up the resin before starting the print...

    IMG_20210124_133130583.JPG

    Not bad I guess. I added quite a lot of supports to the end, and try to solidify it as much as possible to prevent distortion. For some reason, the first corner always ends up distorted on my 45 degree prints. In the image above, it doesn't look too bad actually. Maybe a bit of a lift at the very corner?

    IMG_20210124_133205362.JPG

    Up top, I did add a 2mm vent hole. Just a small thing, but as the print gets to the end lip, it creates a cup and suction would become a problem, distorting the side walls. The ends of the ladders were unsupported and printed great. So far, still looking fine!

    IMG_20210124_133407357.JPG

    Here I've already started removing some of the supports, but I mostly wanted to show that by creating "webs" of tiny supports (0.30mm) it's possible to get small details to print. Still looks "okay" here, maybe a bit of bloating...

    IMG_20210124_140535854.JPG

    Yeah. I really dislike the amount of bloating Siraya Tech Fast creates on any surface pointing towards the build plate. I mean it doesn't look horrible here, but compared to the other end, it just look quite right.

    IMG_20210124_140639926.JPG

    The inside looks fine. I had no supports coming off the floor, none were needed. The inside corner on the right end was slightly distorted, but barely.

    IMG_20210124_140651851.JPG

    No real complaints about the underside, looks fine!

    So I did mention something about paint right? Well, after reviewing the model from the above pictures, I figured I'd give it a coat of black, at least to stop ambient light (which contains some UV) from distorting it. Also, paint will reveal any additional flaws if any...

    IMG_20210124_142802376.JPG

    Ah ha! The right side of the gondola was the end that printed last. We can see that the 2mm drain hole was not quite big enough. There is a very very slight ripple in the wall. At the other end, the left side shows a tiny dip of the lip. So yeah, there is a bit of distortion at that end. Still, I have a feeling that zero distortion is impossible.

    IMG_20210124_142902804.JPG

    IMG_20210124_143026759.JPG

    Look at that!!! that's what I want to see! Crisp lines, the placard is perfectly formed, and the ladders are perfect! Each rib is the same top and bottom! So what about the other end??

    IMG_20210124_143049093.JPG

    Nooo! damn that bloated resin! The placard is a mess, the ribs are hopelessly bloated, and yeah, I have to do a better job of carving out the supports.

    Time to try a completely different resin - I'm giving up on Siraya Tech Fast. I only have half a small bottle left, and will not buy anymore. The rest of what I have will be used on buildings and parts where the underside will never be seen.
     
  9. SLSF Freak

    SLSF Freak Staff Member TrainBoard Supporter

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    Man so close!! It looks fantastic except for the bloat bugger. I'm glad I'm not the only one that goes thru this - it seems like nobody else really talks about it so you assume they don't have any problems. For every new "big" print project I take on I usually have a graveyard of failures where I'm trying to dial everything in to make it a perfect print. I'm so grateful though for the advances this last year with the mono screens - that was a major improvement and made a huge difference in quality. Now, if they can just tackle shrinkage and this bloaty thing we'll be rockin.

    Mike
     
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  10. Sumner

    Sumner TrainBoard Member

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    Well I think it looks perfect. How many times are you or anyone else going to look at it that closely, especially as it is being hauled around the layout ;).

    I've build 3 of my houses and there were screwups in all of them but I sure couldn't find them now. Print those guys out, paint and decal them, put some trucks under them and get them behind a loco. I want to see a train :),

    Sumner
     
  11. Philip H

    Philip H TrainBoard Member

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    if you are after a factory new gon, then no, you are not quite there yet.

    But to model even a modern gon is to love a creature that doesn't stay pristine for long. And while your placard on the one end is not good, its really easy to disguise as damage in operation. So I'd say call it good, paint and weather and enjoy.
     
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  12. Stephane Savard

    Stephane Savard TrainBoard Member

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    Yeah, I suppose I could just leave it as is. But it's going to bug me every time I look at it! Plus yeah I guess a gondola would have some damage... But I want to print at least six, and then they would all have the same damage!

    So, I'm just going to forge ahead until I get it right :D

    Exactly! It's very difficult to find much about these issues... I'm also glad to see I'm not the only one too :D

    Okay, so this bloating thing can be fixed by different resins. If we look back at my very first post in this thread, we can see that it was also at 45 degrees. But I focused then on the distortions. Notice that I never posted a picture of the end that pointed towards the build plate. Let's fix that....

    IMG_20210125_064538355.JPG

    So it's not sanded or anything, not even cleaned up. But we have negligible bloat with the phrozen resin!

    Okay, so what now? It bugs me that the first few millimeters if the print are always a little distorted. Why there and not the other end? I wonder if it's the proximity to the build plate. So this time, back to the phrozen resin, pre heating the vat before printing, and I'm going to raise the model much higher. It will increase build time, but we'll see if it helps with that initial warping.

    Thanks for looking!
     
  13. Stephane Savard

    Stephane Savard TrainBoard Member

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    Sumner, now I'm ready to call the gondola done :D:D:D

    Yesterday late afternoon, I sat down at my computer and spent well over an hour putting in supports to the gondola using Chitubox. Took me so long because I had it crash no less than three times on me. It didn't like the supports I was trying to make :ROFLMAO:

    But in the end, just before dinner I was able to send it off to the printer.

    IMG_20210126_165058232.JPG

    Still on supports, I thought it would be neat to show the new way I used to support the ribs (yeah yeah, change only one variable and all that :whistle:) Those are medium supports but with the connecting parts reduced to 0.3mm. Really I only need to support those ribs to prevent them forming "in mid air", they don't really need heavy supporting. Same with the ladder ends (or tops actually). Notice that I lifted the model a full 15mm from the build plate. Increases build time, but I'm not in a hurry. I was sleeping through most of the print anyway :)

    IMG_20210126_170331301.JPG

    Supports cleaned up, mostly, and now we're at the brake end, the one farthest from the build plate. Like in the Siraya Tech resin, no reason whatsoever for this end to fail, there aren't even any supports on this face. A little nit to pick is the way this resin slightly bows the lip of the gondola. Meh, I can live with that, the ribs aren't bowed at all, just the lip. Plus, to clean up the top, I'll need to sand it down, which will eliminate the worst of it. Weird how this resin looks "rougher" on the faces that are angled 45 degrees (paint will hide that entirely, just like the 45 degree build lines on the sides of the print)

    IMG_20210126_170349685.JPG

    Ah ha!! Will you look at that? Resins are not created equal. So the phrozen resin is more fragile, and may shrink more (I think? More on that later), but one thing is does much better is not bloat like crazy on the model parts facing the build plate. Even the placard printed perfectly. The tiny supports left barely a mark. I should not have broken the supports off the model however, I left some little divots in the lip. I'll know better for next time - better to cut off the supports long and sand down the nubs to make a squared lip.

    IMG_20210126_170413079.JPG

    Nothing exciting under the model, it printed nice.

    IMG_20210126_170425478.JPG

    No bloating means the floor is flawless. So yeah, the lip isn't sanded down yet in this picture. But I managed to screw that up slightly. I just sanded it flat by laying down a sheet of fine sandpaper, and then rubbed the top until smooth. Easy! However, the sheet of sandpaper I've been using is a bit old and completely curled. Instead of taping it down real good, I just held it down and sanded the gondola top. The curve in the paper ended up sanding the gondola corners more than the rest. :whistle: Live and learn from these mistakes, and try not to repeat them! Barely noticeable anyway, won't matter.

    IMG_20210126_170444210.JPG

    This is before sanding down the top (I didn't take any after pictures of that). The left end was closest the build plate, and yes, there is a tiny warp, but had I sanded the top correctly, it would have been perfect.

    So there you go! Can't give up too easily on trying to get it right. Or rather, on trying to get it good enough. This is good enough now. :D

    Next is the fiberglass cover. I have to first draw it up in Fusion 360 though. I only have the old tinkercad STL from my first attempt.

    Oh! nearly forgot, I measured the Gondola. Last time I printed it flat, it was off by quite a lot. For some reason now, I measured it at 101.64mm. The actual model is 101.7mm. I can't explain it! Maybe it has to do with preheating the resin? Not going to complain.
     
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  14. Stephane Savard

    Stephane Savard TrainBoard Member

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    The cover is designed, time to print!

    f360_gondola_full.png
    f360_gondola_under_cover.png
     
  15. Stephane Savard

    Stephane Savard TrainBoard Member

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    I didn't have any specifications, it's just eyeballed based on various photos from ecofab.com.

    upload_2021-1-30_12-30-17.png

    I didn't model the little triangle cages on top, but now wondering if I should try it with some 0.3mm "tube".
     
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  16. SLSF Freak

    SLSF Freak Staff Member TrainBoard Supporter

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    The answer to this is always "yes" (y) Connected wires in close proximity are surprisingly sturdy off these printers. At least in my experience. I've printed some crazy things I was sure wouldn't work only to be proven wrong by my printer. Worst case scenario is you end up with some nubbs that need to be smoothed out with some sandpaper or a file.

    Cheers -Mike
     
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  17. Stephane Savard

    Stephane Savard TrainBoard Member

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    upload_2021-1-30_13-31-22.png

    I found some line drawings on the ecofab website, I was pretty darned close! I'll spend some time to get it closer, and will add the wires on top, if they print it will look awesome!
     
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  18. Stephane Savard

    Stephane Savard TrainBoard Member

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    Ok, now ready for print. Thanks Mike for the encouragement to put in those wires (y)

    Here's the updated screenshot, now matching the line drawing a lot more closely! For those interested, this is how I setup the line drawings in Fusion 360 - just imported as canvases.

    f360_gondola_cover.png
     
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  19. Sumner

    Sumner TrainBoard Member

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    That looks really nice.

    I've also been using the 'canvas' insertion. I wanted to make some cases for Arduino Uno's and Mega's and I can scan them with their PCB board down on the scanner alongside a ruler with the printer to a .jpg file. Then when I import them I can resize them using the marks on the ruler. With the canvas I have all the mounting hole locations to work with without having to measure. Fusion is amazing and has way more features than I'll ever learn,

    Sumner
     
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  20. Stephane Savard

    Stephane Savard TrainBoard Member

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    Fresh off the build plate and cleaned up, printed overnight, an approximate nine hour print...

    IMG_20210131_100109629.JPG

    I made some minor changes to the main body and printed it at the same time. And yes, everything came out quite well. This time I rotated the gondola and the cover 90 degrees, and printed along the width of the build plate instead of lengthwise. It made no difference to the little warps here and there. But I'm glad to see that the cover has zero warping!

    IMG_20210131_110350148.JPG
    IMG_20210131_110405221.JPG

    The above photos show the minor changes I made to the main body. I added a 0.5 mm thick, and 1 mm high "extension" to the ends for the supports. Someone on this thread at one point mentioned using extensions, and while he never came back to explain it more, I did use the idea to prevent damaging the end lips with the support notches. I mean I'm sanding the tops of the gondola flat anyway, so it's just a little bit extra sanding for a perfectly square lip! It did nothing to help with the warping though. Anyway, very happy with this modification.

    IMG_20210131_102814206.JPG

    The cover printed perfectly, I couldn't be more happy about this. Even the wires. SLSF Freak was right about these, totally solid! They even make triangles, so extra strong. I completely forgot to add some support wires to the two corners though (at the corners of the cover, the larger rectangles need a wire support as well). I'll add it to the next one I print.

    IMG_20210131_102827441.JPG

    Here's the underside! The tiny lip around the edge printed quite well too (0.3mm thick). I ended up cracking the cover when trying to remove it from the supports. In the previous picture we can barely see the crack on the top of the cover. Since the crack was lining up perfectly, I painted some liquid resin on the underside and hit it with some UV light, which welded it in place.

    So does it fit? on the first try??

    IMG_20210131_113144344.JPG

    Yes! well, almost. The inside slides perfectly into the gondola itself. But the outer lip on the cover is a hair too narrow and doesn't fall over the main body's lip. The cover was designed with a 0.1mm tolerance between the main body and the cover's lip - I'm just going to increase that to 0.15 or 0.2mm for the next print. I mean it's very very close, and if it fits over the gondola's lip, it will hide the little warps at the corners.

    IMG_20210131_113149694.JPG

    Here's an overall view of the side. I'm very happy with this. Only need some of those minor adjustments I mentioned above and I'm going to start printing the fleet.

    And finally, leaving you with one final picture... the graveyard that got me here! Each print takes approximately 15 ml of resin, for a cost of about 0.60 or 0.70 Canadian dollars. So in total, these twelve failures probably cost me less than ~200ml, or 9$, of resin :D

    IMG_20210131_114032187.JPG
     
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