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Re: [diy_3d_printing_and_fabrication] Resin tuning

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  • Graham Stabler
    ... I d say that if you try and cure for longer you will just make the layer thicker, as long as it is a solid I think it will be fine, even steel when very
    Message 1 of 4 , Apr 18, 2013
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      My question is, how flexible should that layer be? As the layer gets thinner the cured resin is more flexible. Should I increase both the exposure and the pigment to try and make it more ridged or will additional layers in an actual print make that a non issue.

      I'd say that if you try and cure for longer you will just make the layer thicker, as long as it is a solid I think it will be fine, even steel when very thin is flexible. Once you post cure you stiffen it further.

      My next question is about overcure. Specifically, how much more cure depth than the slice thickness is needed for good layer adhesion? For example, if I have my model sliced at .1mm do I need to cure to .15mm? 


      The main limiting factor is damage to the PDMS if you use it, because there is just a thin layer of resin between the VAT bottom and the build platform I don't think you can really overexpose much as far as the resin is concerned. I can't remember the numbers used on the B9 which I own though it is in terms of time not layer thickness.

      Graham 
    • John
      Grahm, thanks for the reply. ... I did a post cure in the sun and the resin did stiffen significantly. It went from a floppy piece of thin rubber to a piece of
      Message 2 of 4 , Apr 18, 2013
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        Grahm, thanks for the reply.

        > I'd say that if you try and cure for longer you will just make the layer
        > thicker, as long as it is a solid I think it will be fine, even steel when
        > very thin is flexible. Once you post cure you stiffen it further.

        I did a post cure in the sun and the resin did stiffen significantly. It went from a floppy piece of thin rubber to a piece of stiff paper. It did curl a bit but that was probobly because it was only exposed to the sun on one side. I was mostly concerned that the rubbery state might allow flexing or warpage of the model as the build progresses.

        > The main limiting factor is damage to the PDMS if you use it, because there
        > is just a thin layer of resin between the VAT bottom and the build platform
        > I don't think you can really overexpose much as far as the resin is
        > concerned.

        What I am calling "overcure" is the distance into the previous layer that the current layer cures so that it fuses securely to the previous one. I guess it's more of an overlap.

        For now I'm using Silguard on my vat floor. My exposure times are so quick that I hope to not damage the coating too quickly. I have the vast floor in a frame so it can be changed easily for a fresh one if it does. With my setup I'm getting a .2mm cure depth with a 1000ms exposure. I'll probobly lower that slightly to get a thickness around .15mm so my layers will overlap by .05mm. Will that be enough or should I leave it at .2mm and have a 100% overlap with the previous layer?
      • Graham Stabler
        ... with the previous layer I think the best course of action is trying it. Graham
        Message 3 of 4 , Apr 18, 2013
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          > Will that be enough or should I leave it at .2mm and have a 100% overlap with the previous layer

          I think the best course of action is trying it.

          Graham

           
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