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Thread: 3D PRINTING A SHIP

  1. #1
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    Default 3D PRINTING A SHIP

    This is my long guide to 3D printing hulls on a resin printer.
    It's aimed at helping someone to start printing but that have already set up the printer. It could still be read by anyone interested in understanding how it's done.

    I have an Anycubic Photon Mono and this description will tell what I do and sometimes perhaps it would be handled differently on another printer and if I know I will then mention that.

    First I will explain how the printer works. It prints by lowering the build plate into a tray (vat) with a plastic film (FEP) bottom that sits over an LCD screen above UV lamps. The tray is filled with resin that hardens when exposed to UV light. When a print starts the build plate is lowered into the resin and just leave a very small space filled with resin between the FEP and the build plate. That space is the height of the slice that the slicer slices the model into. This is usually about the same as the resolution of the screen. In Anycubic Photon Mono the slicing height is 0.050mm or 50µm and the resolution of the screen is 51µm. The screen shows a picture of the slice which means the screen only lets through UV light in the light areas of the picture shown. The Mono is named after having a monochrome screen. Colour screens have three layers of crystals but a monochrome only have one. This mean that it has a better let through and the screen has a lifetime that is almost doubled if monochrome. If the screen show gray scales it would lessen the pixelation of the model. This is called anti-aliasing.



    Files that can be used for the 3D models to be printed are usually STL-files. I have bought them via Kickstarter, Wargaming3D, MyMiniFactory or there are free files on at least Thingiverse and perhaps some other places too. The web pages mentioned that sell models also have some free samples. The printer can't read an .stl file so you will need a program to create the correct file for your printer.

    The software program needed to work with the file and to prepare and slice it for the printer is usually called a slicer software. There are several to choose from. The most known are Lychee Slicer and Chitubox. These are available for free. For my printer there's a free software that comes with the printer too, called Anycubic Photon Workshop. I use Lychee because I like the way the supports work. More about supports later on.

    When printing for Sails of Glory the target scale is 1:1000. The most common scale for the files are 1:700. This means the model have to be scaled. From 1:700 to 1:1000 use the scale at 70%. This scaling can affect how well a model will print. Some details may become too small to print well or make details, like the guns, too fragile. Here there are a few alternatives to handle this. Henry Turner have in his ships for Cape St Vincent included several files for different scales, including 1:1000, but this is not done in his earlier Baltic Bulwarks. There are also often files for both resin and FDM. This means there may be several files to choose from. I have noted that FDM files in 1:700 often is used as the resin file for 1:1200 or 1:1000. I usually choose 1:1000 if there is one, otherwise 1:700 FDM printed in 70% or 1:700 resin in 70% depending on how fragile details may be.

    When the scale is sorted out it's time to put the models on the virtual build plate. You can fill the build area as you like. I usually arrange my ship hulls manually. Lychee can arrange the objects automatically. For ships of the line I usually put them located at -50mm, -25mm, 0mm, 25mm, 50mm in X to make them fit on the build plate. That gives me five ships in a single printing. There's the possibility to adjust them in Y too, to put some smaller accessories along the edge if there's some of those to be printed. I have found ships boats and anchors. In Z the models could be printed flat on the build plate, but this have some problems attached to it.

    The first and biggest is that the first few layers are exposed to UV-light for a longer time to help it stick to the build plate. This makes the first few layers swell from the model and give a bit of a lip or a foot. This would look quite strange if it's the hull that slims toward the waterline. Instead it's better to put the ship hulls on supports above the build plate. The minimum height of Z to fit supports is 5mm in Lychee.

    The second problem is that if you print the ship horizontally the entirety of the ship will be printed in the same layer. Why this could be a problem will be explained later.

    Lastly, when printing a sloping surface, like the poop deck on a ship, the slope would be built up in steps. If these steps are close to each other they can hardly be noticed, but if they are a few millimetres apart they will be quite visible. This means that surfaces close to horizontal but not quite can look worse than steeper surfaces. This problem can be lessened by tilting the ship. There will still be stripes across but instead of the noticeable version they'll still be there but as they are quite small, if they are more consistant they not that noticeable. I have tested some different tilting angles.

    I would recommend somewhere about 15-30 degrees. The more the hull is tilted the higher the total print volume gets and the longer the print will take. I usually use 20 degrees. Resin printers will print details better if they face away from the build plate than towards the build plate due to how the printer works. I therefore raise the stern of the ship to make sure the stern gallery prints well.



    I have alternated direction of the ships to balance the suction when the cured resin sticks to the FEP. It should mot matter if the build plate is well tightened and there's no play in the printer. As there probably is a little, I prefer to try to balance the print.

    When placing supports I do not use autosupport. I find that it's a bit random and supports things that don't need supports and put supports on the side on the hull leaving ugly marks where they have been removed. Instead I place them manually. I place medium supports on the bottom of the hull, closer together at the lowest parts to ensure that the hull doesn't come off while printing and a bit more spaced out along the length at the hull. I usually put them at the same spacing as the guns and do a pattern covering the bottom. The reason for using medium instead of heavy supports is that when placing them too wide apart the area in between will be "sagging". If there's many heavy supports placed closely together there will be a hard time removing the hull from the supports. The details I have found needs supporting depends on the model. Henry Turner's models often benefit from having the catheads supported. There I use light supports and on smaller ships I even manually change the needle point to 0.20mm or even 0.15mm to make sure that it's the support that will break and not the ship when I try to cut it off. Parts I support with smaller supports: The stem, the rudder, catheads and in a few cases, the lanterns on the gallery.

    One thing to think about is that the lowest parts of the model absolutely needs to be supported, otherwise it will be an unsupported island, floating around without being connected to anything. That means that the resin will just stick to the FEP. If that resin isn't removed it will make later prints fail and it can even stick so hard it will ruin the FEP and even cause a hole making it leak. FEPs are consumables and will have to be changed from time to time.



    When the file is ready to be printed you can usually slice it in the slicing software I suggested above, but I have downloaded an upgrade to the firmware of my printer that adds anti-aliasing and the last I heard, Neither Lychee or Chitubox supports that for my printer. Therefore I save the finished print as both a .lys (Lychee file, to be able to come back to it) and a .stl. I then open that .stl in Anycubic Photon Workshop. Slicing the file using that gives the Anti-Aliasing (gray scales) in the print and lessening the square effects of the pixels I wrote about above. When it's imported as a .stl it's a fixed object and that's why it's a good thing to save the .lys file earlier.



    Here the object has to be rotated 90 degrees to fit on the build plate. Then I select to slice the file using the Anycubic Photon Workshop. It creates a kind of movie of every layer of the model that will be played on the display of the printer letting UV-light hit the resin and making it solid. That movie is a file called .pwmo that will be copied to a USB memory stick. I use the memory stick that came with the printer.



    The film at the bottom of the tray is called FEP. This has to be able to flex just enough to let go of the printed resin without creating too much suction. It's good to not have a too big a surface lit up at the same time. If you want to print a big structure, you ought to hollow out the inside to make it print well. In the case of ships, the angling makes the section printed in each layer smaller and helps out in this way too.

    To start printing fill enough resin into the tray. The slicer software will tell you how much resin will be needed for the print. Make sure to have more than that. Unused resin can be poured back into the bottle. There's filters that is good to use as small parts from a failed print may not only destroy the next print but even the FEP and possibly even the display itself.



    Then put the memory stick containing the file to print into the printer. On my printer I just turn it on and choose print in the menu and then select the file to print and it'll start.



    It lowers the build plate down into the resin and the screen shows the first picture in the "movie" that is all the slices. After exposing the resin to the UV light it raises the build plate to let the resin let go of the FEP. The build plate then lowers back down in the resin and leave a new slice of 50µm resin that then get exposed to UV light and so on. The first layers are designed to stick firmly to the build plate.



    Here the build plate is back down and is printing the supports. You can see that there's a little concentration of supports at the stem of the ships.



    When the print is finished the build plate return to the top position. As you can see the ships are printed upside down, from the plate up.



    When the print is finished I remove the entire build plate from the printer.



    ...and put it in the Wash and Cure station. It has a wire cage that you can place loose printed objects in, but I use the holder for the build plate as that stops the models from possible damage due to being thrown around in the washing. At the bottom of this container there is a propeller that turns in one direction for a minute and then changes direction to twirl the cleaning liquid around the models.



    I watched a youtube movie about what liquid to use and during the pandemic there's been a shortage of alcohol to use, so someone experimented with different cleaners and got as good or better results with Mr Clean as with alcohol. My resin is also water washable. This makes handling quite a lot easier. There's an interesting way to handle the used washing liquid. The used liquid could be put in the sun. This makes any uncured resin in the washing liquid cure and fall to the bottom. Uncured resin is a chemical that should be handled carefully, but cured resin can be thrown in the garbage.



    I let the build plate drip off on the edge of the container for a while and then I just hold them under the water faucet to wash off any remaining cleaner.



    Then it's time to remove the models from the build plate. A scrape came with the printer. As you ca see I use a protective glove. Make sure it's a chemically resistent glove as not all are. Mine are made of nitrile.



    As you can see there are a lot of scratches on the build plate. This is a good thing. It helps the cured resin to stick to it. If the build plate is very smooth it is recommended that you use a coarse sandpaper to rough up the surface some.



    It differs some if I remove the supports or not before curing/painting... But even if I keep supports I cut off the outermost supports close to the edge of the hull. I don't want a sliver of the edge to come off when it's painted and finished. Before curing the resin is a little rubbery. This is very good when removing the supports as otherwise a part of the model might crack off as the resin be becomes quite brittle with suring. This is especially good tor removing the supports for more delicate details as the catheads or lanterns.



    Putting the models in the W&C make sure that it is in the right configuration of "Cure" and not "Wash", otherwise it will spin up fast and send the models flying. After curing them upright for five to seven minutes I usually put them on their side and cure them for a few minutes more to make sure they're not sticky.



    These last steps of washing and curing can be done using any container holding washing liquid and sloshing around the model. The curing can be done by putting the model in the sunlight or in a nail polish curing lamp. Those things is probably at least a hundred dollars cheaper than buying a Wash and Cure station, but I don't regret my buy for a second. It's so much easier and my handling of uncured models have been reduced a lot. This makes for less of a risk of me damaging a model or getting an uneven exposure of UV light and perhaps making some models not fully cured and others very brittle from overexposure if that is a risk. At least if gives consistency.

    A note. Make sure that you don't have any resin scrap sticking to your model before you cure it. Resin parts are very sticky and if cured touching something it will cure like an integral part of the model.
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    Last edited by TexaS; 06-19-2021 at 17:55.

  2. #2
    Comptroller of the Navy Board
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    Thanks for the crash course, Jonas. :)
    --Diamondback
    PMH, SME, TLA, BBB

  3. #3
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    great introduction, thank you :-)

  4. #4
    Admiral of the Blue.
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    I have merged the post and put it in the How To section for you Jonas. Now it will be easy for anyone to access as this thread sinks below the Horizon.
    Rob.
    The Business of the commander-in-chief is first to bring an enemy fleet to battle on the most advantageous terms to himself, (I mean that of laying his ships close on board the enemy, as expeditiously as possible); and secondly to continue them there until the business is decided.

  5. #5
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    Thank you, Rob. I’m still doing touch ups. I guess I’ll do that there.

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