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Re: mirror making

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  • Art
    Hi Michael! Dave Kelly brings his his auto-collimator to Stellafane every year. He combined the tracks, the main mirror and the fixture for holding the tests,
    Message 1 of 18 , Mar 23, 2011
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      Hi Michael!

      Dave Kelly brings his his auto-collimator to Stellafane every year. He combined the tracks, the main mirror and the fixture for holding the tests, all into one rectangular tunnel. The tunnel actually helps support the test apparatus. It's easily 15% of the volume of ours.

      To see what it looks like, go to the PHOTOS section and look for KELLY's AUTOCOLLIMATOR

      Art


      --- In delmarvastargazers@yahoogroups.com, Michael Lecuyer <mjl@...> wrote:
      >
      > Many of the holes in the tubing are stripped - replacing screws won't
      > help - bigger screws will strip too. The screws are much harder than the
      > thin tubing. I don't think cable ties have the necessary strength to
      > hold anything - they're pretty weak. Adjustable wire cables work the
      > best. The current structure is beyond repair, difficult to build and
      > requires too many people to set up.
      >
      > A total PVC construction would be stiffer but bulky to store. 1 1/2" PVC
      > is strong and reasonably stiff over 7'. I've build free standing
      > structures that have worked for several years and none are glued. It's
      > easy to attach material to them using PVC clamps (they look like 2/3rds
      > of a PVC pipe and much thinner).
      >
      > Other ideas were mentioned at the MMS - lets hear them.
      >
      > On 3/15/2011 21:05 PM, Don Surles wrote:
      > > I would rather do an inspection of the connectors for the testing tunnel
      > > (at the star party) and replace screws as necessary. we could also add a
      > > diagonal brace to each side to prevent rocking...this could be as simple
      > > as some 1/2" conduit and cable ties...conduit should be about 210 inches
      > > long...could be pvc.
      >

    • Paul Riley
      Spring is here, and so is the April issue of Star Gazer News.   Members can download here:  
      Message 2 of 18 , Mar 26, 2011
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        Spring is here, and so is the April issue of Star Gazer News.
         
        Members can download here:
         
         
        Non-members can also download to see what the Gazers are all about.
         
        Comments ?
         
        email to : dmsg_pjr@...
         
        Pj

      • Michael Lecuyer
        Art: Kelly s auto-collimation device looks really solid. The problem with the current tunnel we use is not necessarily its size but its construction. There is
        Message 3 of 18 , Apr 2 2:04 PM
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          Art:

          Kelly's auto-collimation device looks really solid.

          The problem with the current tunnel we use is not necessarily its size
          but its construction. There is no good way to fix it. Adding bolts and
          tension elements would seem to add to the difficult installing it.

          I have an alternative free standing tunnel skeleton that I'll bring to
          the upcoming Star Gaze. I will assemble it by myself with no additional
          help. The metal tunnel requires around five people and chairs (and
          hopefully one or two tall people). My alternative has no sharp bits on
          it to tear the shroud. For a small extra charge sharp bits can be added
          for backwards compatibility.

          I put it together today in a bit of wind and it really is free standing.
          I looks huge even outside although built to similar dimensions of the
          old tunnel. Right now its a prototype for an interior room I'm putting
          in my workshop.

          It could be scaled down to be similar to the auto-collimation box. There
          is only one side strut at the eight foot mark.

          On 3/23/2011 22:40 PM, Art wrote:
          > Hi Michael!
          >
          > Dave Kelly brings his his auto-collimator to Stellafane every year. He
          > combined the tracks, the main mirror and the fixture for holding the
          > tests, all into one rectangular tunnel. The tunnel actually helps
          > support the test apparatus. It's easily 15% of the volume of ours.
          >
          > To see what it looks like, go to the PHOTOS section and look for KELLY's
          > AUTOCOLLIMATOR
          >
          > Art
          >
          >
          > --- In delmarvastargazers@yahoogroups.com, Michael Lecuyer <mjl@...> wrote:
          > >
          > > Many of the holes in the tubing are stripped - replacing screws won't
          > > help - bigger screws will strip too. The screws are much harder than the
          > > thin tubing. I don't think cable ties have the necessary strength to
          > > hold anything - they're pretty weak. Adjustable wire cables work the
          > > best. The current structure is beyond repair, difficult to build and
          > > requires too many people to set up.
          > >
          > > A total PVC construction would be stiffer but bulky to store. 1 1/2" PVC
          > > is strong and reasonably stiff over 7'. I've build free standing
          > > structures that have worked for several years and none are glued. It's
          > > easy to attach material to them using PVC clamps (they look like 2/3rds
          > > of a PVC pipe and much thinner).
          > >
          > > Other ideas were mentioned at the MMS - lets hear them.
          > >
          > > On 3/15/2011 21:05 PM, Don Surles wrote:
          > > > I would rather do an inspection of the connectors for the testing
          > tunnel
          > > > (at the star party) and replace screws as necessary. we could also
          > add a
          > > > diagonal brace to each side to prevent rocking...this could be as
          > simple
          > > > as some 1/2" conduit and cable ties...conduit should be about 210
          > inches
          > > > long...could be pvc.
          > >
          >
          >
        • Art
          Michael wrote: The problem with the current tunnel we use is not necessarily its size but its construction I agree with you that the construction method is
          Message 4 of 18 , Apr 15 9:50 PM
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            Michael wrote:  " The problem with the current tunnel we use is not necessarily its size but its construction"

            I agree with you that the construction method is the primary problem. I assert, however, that its size magnifies the problem.

            Our tunnel contributes nothing to the stability of our test device. It only contributes darkness and even there, the result is not what it could be given the size of the opening at one end.

            I see no reason why the two structures have to be seperate. Combining the two promises to make eveything better.  

            The 2 x 4's cureently used to support the PVC pipe guides are heavy and lack beam strength.

            Rails made like engineered beams would be lighter and stiffer. We could, with little effort. make smaller tent frames out of 1/2" PVC . It would take up a lot less room when in use  and a lot less when stored. Set up would be easier.too, because it's not so big.

            Thanks for addressing this issue. I'm sure that Steve Swayze will also be pleased.

            Art

            .--- In delmarvastargazers@yahoogroups.com, Michael Lecuyer <mjl@...> wrote:

            >
            > Art:
            >
            > Kelly's auto-collimation device looks really solid.
            >
            > The problem with the current tunnel we use is not necessarily its size
            > but its construction. There is no good way to fix it. Adding bolts and
            > tension elements would seem to add to the difficult installing it.
            >
            > I have an alternative free standing tunnel skeleton that I'll bring to
            > the upcoming Star Gaze. I will assemble it by myself with no additional
            > help. The metal tunnel requires around five people and chairs (and
            > hopefully one or two tall people). My alternative has no sharp bits on
            > it to tear the shroud. For a small extra charge sharp bits can be added
            > for backwards compatibility.
            >
            > I put it together today in a bit of wind and it really is free standing.
            > I looks huge even outside although built to similar dimensions of the
            > old tunnel. Right now its a prototype for an interior room I'm putting
            > in my workshop.
            >
            > It could be scaled down to be similar to the auto-collimation box. There
            > is only one side strut at the eight foot mark.
            >
            > On 3/23/2011 22:40 PM, Art wrote:
            > > Hi Michael!
            > >
            > > Dave Kelly brings his his auto-collimator to Stellafane every year. He
            > > combined the tracks, the main mirror and the fixture for holding the
            > > tests, all into one rectangular tunnel. The tunnel actually helps
            > > support the test apparatus. It's easily 15% of the volume of ours.
            > >
            > > To see what it looks like, go to the PHOTOS section and look for KELLY's
            > > AUTOCOLLIMATOR
            > >
            > > Art
            > >
            > >
            > > --- In delmarvastargazers@yahoogroups.com, Michael Lecuyer mjl@ wrote:
            > > >
            > > > Many of the holes in the tubing are stripped - replacing screws won't
            > > > help - bigger screws will strip too. The screws are much harder than the
            > > > thin tubing. I don't think cable ties have the necessary strength to
            > > > hold anything - they're pretty weak. Adjustable wire cables work the
            > > > best. The current structure is beyond repair, difficult to build and
            > > > requires too many people to set up.
            > > >
            > > > A total PVC construction would be stiffer but bulky to store. 1 1/2" PVC
            > > > is strong and reasonably stiff over 7'. I've build free standing
            > > > structures that have worked for several years and none are glued. It's
            > > > easy to attach material to them using PVC clamps (they look like 2/3rds
            > > > of a PVC pipe and much thinner).
            > > >
            > > > Other ideas were mentioned at the MMS - lets hear them.
            > > >
            > > > On 3/15/2011 21:05 PM, Don Surles wrote:
            > > > > I would rather do an inspection of the connectors for the testing
            > > tunnel
            > > > > (at the star party) and replace screws as necessary. we could also
            > > add a
            > > > > diagonal brace to each side to prevent rocking...this could be as
            > > simple
            > > > > as some 1/2" conduit and cable ties...conduit should be about 210
            > > inches
            > > > > long...could be pvc.
            > > >
            > >
            > >
            >

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