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[Fwd: ATM Tinsley 26" problems - third round(success)]

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    Report on the Friday night efforts:

    Long Version (Short Version at bottom of message)

    This past friday night, Steve Neal (another observatory committee
member) and I went to the observatory to tackle the problems that
existed.  We went armed with the advise from this list, more than a
handful of tools and time.
    1. First item of business was to retest and confirm the issues and
see if there was any  change from the previous session.  No changes were
noted.  Next we changed eyepieces to confirm that the eyepiece was not
at fault, by using my personal set of Naglers, same results.
    2. Second was the change of position and targets to see if any
changes were noted, no difference.
    3. Third item was to get up close and personal with the primary
mirror.  We first discussed an organized plan of attack and  got to
work.  We removed the accessories from the mirror end and parked the
telescope with the tube in a completely vertical mode and powered down
the control console after locking the tube in place.  Next we removed
the shrouds that enclose the support tubes that lead down from the
center pivot casting.  Once all this was done we took stock of what we
had to work with.  The mirror rests on the cell supported by 18 points
and is retained axially by six approx. 1/2" all thread bolts with screw
slots on the exterior.  These bolts have a hollowed end holding a ball
bearing pivot that presses against curved steel plates that are lined
with 1/8" teflon.  These plates in turn, lightly press against the outer
edge of the mirror.  These plates have a radius that appears to be just
slightly smaller than the outer circumference of the mirror resulting in
a small gap in the center which allows the pad to be pre loaded a small
amount.  On top we found a ring with three clamps that is intended to
retain the mirror should it ever attain a slight nose down attitude.
    4. After carefully examining the mechanism we proceeded to unload
the radial bolts and found a couple of bolts had too much pressure on
them.  We carefully backed the bolts enough to allow adjustment without
loosing the ball bearing from the bolt end.  Next we removed the
retaining ring, which was tight against the mirror face and removed the
clamps fastened to it.  It was decided to rotate the mirror approx. 60
degrees.  This allowed us to confirm contact with all the support points
and if the problem was totally with the mirror, then the double image
would shift also.
    5. We took a deep breath and carefully examined the mirror face and
found that it was extremely dirty and the outer retaining ring had
pressed against the mirror face hard enough to leave marks.  We
proceeded to puff off the large particles of dirt with a puffer and  to
lay soft cloths on the mirror face that had been damped with water.  We
gently pressed the cloths down to achieve full contact with the face and
left the cloths there for several minutes.  Next we carefully lifted the
cloths from the face and lifted lots of dirt with them.  We then damped
the mirror face with water and used a large soft lint less cloth to pat
the surface, and then let this dry.  Another examination showed no
visible dirt or particles, however, we still had a film on the surface.
Steve took to the task with lens cleaner in hand and lens tissues to
apply the solution.  I followed up with another lint less soft cloth
with small circular strokes and no pressure to clean the film off.  Next
another soft cloth was used to polish the surface  leaving a very clean
mirror.  The coating was examined and it's our opinion that at some
point the mirror will have to be recoated, as the current coating shows
some pitting and blemishes.
    6.  We prepared to reassemble the scope but first we attached felt
to the under side of the retaining ring to give a slight amount of
cushion to prevent scaring of the mirror face and allow movement and
growth of the materials without altering figure.  The radial bolts were
adjusted to allow a uniform amount of axial rock to the pressure pads,
and still let the mirror expand radially with temperature.  We turned
down the red lights in the dome and checked the optics.  Since the scope
has a field of view of less than 15 min. with a 55 mm eyepiece we were
unable to align with an alignment star however the pinpoints of
extremely faint stars was encouraging.  It was decided to completely
reassemble the scope and attach the finders and align them.  We then
finally attained an alignment star and the image was blinding, the star
was so focused that it hurt to look at it.  Next we tested outside of
focus and inside of focus and obtained nice concentric circles with just
a slight hint of surface roughness.  We proceeded to clean the corrector
in a similar manner and then cruised the skies a little.
    7. When we examined M42 we attained a sharp image showing a visible
six core stars and another visible eight plus stars in the innermost
tendrils of nebulosity.  The night of long overdue maintenance was well
worth the six hours it took.  We still plan to revisit the collimation
issue next, however this coming friday I think we will just kick back
and once again enjoy Sky Piloting.  Maybe we will complete the computer
interface prior to session, just hope the skies are clear and cool.



Short Version
We took it apart, cleaned the optics. Put it back together. Had no spare
parts left over. It worked.


Many thanks to the suggestions and opinions we received from the list.
One lesson here is to ask, the other is never work on optics with more
than one tool in hand at any time.  Our plan was to work safely and
carefully, and not ruin optics crafted more than thirty years before.

Warmest Regards
Frank Sperl
Robinson Observatory Committee
Central Florida Astronomical Society

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