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  1. #21
    Peachy Printer Founder
    Join Date
    Sep 2013
    Posts
    308
    Quote Originally Posted by Slatye View Post
    I don't think so. Say you've got 1mm of resin on top of the water. Obviously for the first 1mm of the cube there can't be any water inside it; the water layer starts below the bottom of the cube. For the next layer (ie 1.01mm or so) the water is above the bottom of the cube, but it can't get into the cube because the walls of the cube prevent it. The only thing that can get into the cube is the resin, which goes right up to just over the top of the partly-completed cube. This continues all the way up; the cube sides are always just under the top of the resin layer, and above the top of the water layer. Therefore the water can never get in.

    One thing to be careful of here is that you might need quite a lot of resin, even if you're not using the laser to solidify all of it. A 100x100x100mm cube will require a litre of resin even if you only actually use the laser to solidify the sides - the entire interior will be full of resin too. If you wanted a solid cube than that's no big deal - obviously a 1L solid cube is going to require 1L of resin.

    What if you wanted it to be hollow with 1mm wall thickness (total volume of the finished cube 0.06L)? If you print it with a hole at the bottom it'll still require a full 1L of resin, because the hole will be covered by the build platform. Once it's finished you can take it off and drain the spare 0.94L of resin from it, but if you don't have at least 1L of resin to begin with then the job will never finish. Same applies to a hole at the top - you can get the spare resin back but you have to load the printer up with 1L of resin first. If, however, you have a hole very low on one side then the water will be able to flow into the cube during the build. Now you can get away with only having 0.06L of resin (or, more realistically, about 0.1L so there's a bit to spare) for the print job.
    This is completly correct, Great Thinking everyone!

  2. #22
    Student
    Join Date
    Oct 2013
    Location
    nederland
    Posts
    10
    Quote Originally Posted by Slatye View Post
    I don't think so. Say you've got 1mm of resin on top of the water. Obviously for the first 1mm of the cube there can't be any water inside it; the water layer starts below the bottom of the cube. For the next layer (ie 1.01mm or so) the water is above the bottom of the cube, but it can't get into the cube because the walls of the cube prevent it. The only thing that can get into the cube is the resin, which goes right up to just over the top of the partly-completed cube. This continues all the way up; the cube sides are always just under the top of the resin layer, and above the top of the water layer. Therefore the water can never get in.

    One thing to be careful of here is that you might need quite a lot of resin, even if you're not using the laser to solidify all of it. A 100x100x100mm cube will require a litre of resin even if you only actually use the laser to solidify the sides - the entire interior will be full of resin too. If you wanted a solid cube than that's no big deal - obviously a 1L solid cube is going to require 1L of resin.

    What if you wanted it to be hollow with 1mm wall thickness (total volume of the finished cube 0.06L)? If you print it with a hole at the bottom it'll still require a full 1L of resin,
    Make the hole in the side.



    jankoohole1.jpg
    Last edited by jankoo; 01-29-2014 at 10:38 AM.

  3. #23
    Quote Originally Posted by Slatye View Post
    I don't think so. Say you've got 1mm of resin on top of the water. Obviously for the first 1mm of the cube there can't be any water inside it; the water layer starts below the bottom of the cube. For the next layer (ie 1.01mm or so) the water is above the bottom of the cube, but it can't get into the cube because the walls of the cube prevent it. The only thing that can get into the cube is the resin, which goes right up to just over the top of the partly-completed cube. This continues all the way up; the cube sides are always just under the top of the resin layer, and above the top of the water layer. Therefore the water can never get in.

    One thing to be careful of here is that you might need quite a lot of resin, even if you're not using the laser to solidify all of it. A 100x100x100mm cube will require a litre of resin even if you only actually use the laser to solidify the sides - the entire interior will be full of resin too. If you wanted a solid cube than that's no big deal - obviously a 1L solid cube is going to require 1L of resin.

    What if you wanted it to be hollow with 1mm wall thickness (total volume of the finished cube 0.06L)? If you print it with a hole at the bottom it'll still require a full 1L of resin, because the hole will be covered by the build platform. Once it's finished you can take it off and drain the spare 0.94L of resin from it, but if you don't have at least 1L of resin to begin with then the job will never finish. Same applies to a hole at the top - you can get the spare resin back but you have to load the printer up with 1L of resin first. If, however, you have a hole very low on one side then the water will be able to flow into the cube during the build. Now you can get away with only having 0.06L of resin (or, more realistically, about 0.1L so there's a bit to spare) for the print job.
    i just rewatched some videos, and im pretty sure the water can flow in from below. See: http://www.peachyprinter.com/#!Our-M...0-2C7F1C26381F

  4. #24
    Technologist
    Join Date
    Oct 2013
    Posts
    110
    Quote Originally Posted by masterada View Post
    i just rewatched some videos, and im pretty sure the water can flow in from below. See: http://www.peachyprinter.com/#!Our-Most-Complex-Prints-Yet/cn7f/AC2F904C-CBCD-4BD9-80B0-2C7F1C26381F
    Ah, nice point. That video used a mesh build platform. I was assuming that you'd use a solid/flat build platform, like FDM printers do. However, they use it because with FDM the base of the part conforms to the surface of the build platform (so a rough build platform means a rough part) and using a mesh would make it nearly impossible to remove the part from the bed.

    The Peachy just doesn't care about that. The base will always be flat because it conforms to the shape of the resin (which is flat because it's a liquid). As long as some point on the base makes contact with the build platform, that'll keep the part in position and you can still get water coming in from the bottom. Presumably afterwards you could just lay a bit of sticky tape over the base (to seal it), dribble in a bit of resin (which will sit on the tape and cover the hole in the base) and then leave it out in the sun for half an hour to cure.
    Last edited by Slatye; 01-30-2014 at 07:25 AM.

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