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3517Re: I've got focus.

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  • vrsculptor@hotmail.com
    Sep 3, 2011
      That is a good question that deserves a thoughtful answer. Please keep in mind that for me this is a hobby and being retired time spent is not an economic consideration.

      The requirements for resolution depend on the use for which the tool is used and accuracy costs effort and money. If you are doing prototype work that requires precision as in an assembly that requires snap fits a tolerance of a couple of thousands is required. If you are producing patterns for castings or you expect secondary machining resolution is not so important. I'm looking at doing patterns (via silicone) for lost wax and resin castings. The patterns will be post processed as needed.

      I'm also very curious (as you pointed out) the implications of size on curing time. The UV light drops with the square of the area. A .007 inch thick layer will take longer to cure than a couple of microns but this may be offset by the number of layers required. I honestly don't know.

      Speed, if you doing your own projects, is not much of a consideration. If I'm doing profiling on the mill a job may run for many hours. With a simple machine like a DLP printer parts can run overnight. I feel much safer letting this run unattended than my mill or a RepRap machine.

      KISS. Another thing I've learned along the way is that while learning and experimenting it is often useful to go with the simplest mechanism that will work and if you find it useful undertake a more sophisticated project. I started with CNC'ing a HF mini-mill and ended up converting a very large 7000# mill.

      I bought Dymax for $150/liter. I think that works out to about $2.50 a cubic inch. I can afford that at least as far as testing goes. With luck something cheaper may come along.

      I think at even .007 resolution a DLP printer might be better than a RepRap. I don't think that the state of the art in either RepRap or our DLP printers has reached the point that they justify sophisticated solutions. Cost of this project, because of a well stocked junk box, will be less that $300. That is pretty low cost in terms of education and entertainment and I've already learned much more than I wanted to know about light sources and optics.

      If all goes well who knows. I may build a sliding DLP based system with a huge build area and high resolution.


      PS. Was even able to focus to a smaller size using method described. I knwo I hit 4 inches.

      --- In diy_3d_printing_and_fabrication@yahoogroups.com, "techartisan" <metalations@...> wrote:
      > Im not trying to put your work down, I am just curious about your build intention.
      > you are using an xp7030...1024X768 projector....
      > At 7 inch wide your xy voxel dimension .0068in, .172mm or 173.72 microns....seems rather large in comparison to Eteks 43-73 typical xy micron dimension.
      > Is there a reason youve chosen to go low res? This is essentially reprap build resolution, at a much higher material cost. Beyond limiting your surface resolution, have you considered the effect this dispersion will have on layer cure time? Given the (prolonged exposure time:full layer build) it would be interesting to see how your build time would compare to a reprap on the same part.
      > Again not criticizing, just curious why youve made this choice as most see DLP as a way to enhanced part resolution at the expense of heightened material costs.
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