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3521Re: [diy_3d_printing_and_fabrication] Re: I've got focus.

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  • Fernando
    Sep 4, 2011
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      OK, damage limitation mode:
      I just bought myself another HP VP6121 projector for parts from ebay.
      I will be more comfortable tinkering around on the projector with the
      knowledge of having replacement parts to fall back upon.

      In the meantime, I will have to go back to the test rig for making the
      initial resin system comparisons. This will all set me back somewhat,
      but what's a kid to do...


      On Sun, 2011-09-04 at 18:42 +0200, Fernando wrote:
      > Oh dear...
      > Everything was going so nice and I have majorly fuc#ed up!
      > I was so happy because I had tweaked the lens assembly positioning in a
      > way that the distortion was gone and I was trying out throw distances
      > with the color wheel out of the way. Everything was just rosy!
      >
      > But then I noticed there was a band of dirt on the left side of the
      > picture and I assumed there must have been a spot I missed cleaning in
      > the optics. The only part I hadn't yet thoroughly cleaned was the light
      > integration tunnel. In a projector that is a rectangular section, hollow
      > (or solid) tunnel that catches the light from the lamp and carries it to
      > the DMD module. So I went and used some lens cleaning fluid and a cotton
      > stick to try and clean it.
      > The bad surprise was when the cotton tip came back out with some alu
      > scales on it, looking suspiciously like mirror residue to me. So I
      > quickly assembled the projector back, switched it on and indeed, the
      > image was almost completely gone!!! I cannot believe I just destroyed my
      > projector just before the all important resin curing tests... I'm so
      > frustrated right now I could burn the damn filthy projector in a pyre!
      >
      >
      > On Sun, 2011-09-04 at 14:42 +0000, vrsculptor@... wrote:
      > >
      > > Fernando,
      > > I tried shimming the lens assembly out and got distortion. Admittedly
      > > my shimming was on the crude side and may have been the problem. That
      > > is why I ended up shimming the focusing ring. Your solution is much
      > > better, if you can fix the distortion, as you have a variable throw
      > > while mine if fixed.
      > >
      > > Please keep us posted.
      > >
      > > Roger
      > >
      > > > This is something I have been giving some thought and doing some
      > > work as
      > > > well. While modifying my projector's optics, I have managed to
      > > forward
      > > > the optics module for about 2mm within the flange that supports it,
      > > > which provided the possibility to focus at significantly closer
      > > ranges:
      > > >
      > > > From stock, my DLP was able to produce a smallest area of 230x280mm
      > > at
      > > > 530mm throw distance.
      > > >
      > > > After modification I am now able to throw images of
      > > > 135x110mm at 230mm distance
      > > > 200x150mm at 350mm distance
      > > > 230x280mm at 475mm distance
      > > >
      > > > This gives me a nice range of precisions and sizes to work with and
      > > has
      > > > urged me to modify my printer structure to accommodate a rail to
      > > support
      > > > the DLP. It's a pretty simple mod and this way I will be able to
      > > adjust
      > > > size and resolution to suit my needs. The only caveat here would be
      > > > calibrating dimensions from the 3D model to the print stage.
      > > >
      > > > NOTE: while fiddling around with the (incredibly filthy) optics to
      > > clean
      > > > them up and shorten the throw I have introduced some distortion. I
      > > will
      > > > have to carefully tweak around the positioning of the lens module to
      > > > correct it.
      > > >
      > > > In the meantime, my In-laws have arrived for a vacation and all the
      > > DIY
      > > > work is grinding to a halt.........
      > > >
      > >
      > >
      > >
      > >
      > >
      >
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