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6 - Rebuilding/Restoring the TAL 6x30
Finder |
The TAL 6x30 Finder is relatively
straightforward to strip down. You will need some precision/jewellers cross
head screwdrivers though as most of the screws on this are very small.
As ever with optical
components exercise extreme care. One slip of a screwdriver can ruin an
otherwise perfectly sound optical assembly.
This unit was stripped as it
was suffering a host of problems including a sticky focuser that made a nasty
grinding sound when adjusted, dirt inside tube, lens components were very grubby and the exterior finish was
ruined.
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Stage 1 - Stripping down the
6x30 finder |
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Remove the finders rings if desired. You need not do
this unless you are planning refinishing the finder scope tube. The rings are
held on with three small set screws around each ring. These need to be
slackened off. |
To remove the front lens you will need to slacken off
the small set screw at the front of the finder scope tube. |
The primary optic should be easy to move once the set
screw in the previous step has been loosened. Using a small screwdriver you can
gently push the lens holder around to unscrew it using the small slots in the
lens holder. |
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One enough of the lens holder is showing its easy to
unscrew this with your fingers. This unit showed signs of wear and broken paint
inside the finder tube. The lens was also very dirty. |
The primary optic is removed and cleaned with an
isopropyl alcohol and water mix (1 part IPA and 10 parts water). The lens on
this unit was absolutely filthy. |
The rear optical elements are held in place with a small
set screw located just in front of the rear element. Loosen this screw. |
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The rear optical assembly is removed by
simply unscrewing it. This will be stripped down later to fix its rather
'gritty' feel. |
If desired the rear plate of the finder scope tube can
also be removed by slackening off the small set screw at the rear of the
tube.... |
...and simply unscrewing the rear plate. |
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Stage 2 - Stripping and Repainting the Finders Optical
Tube |
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Like the main tube the finder paintwork was very
yellowed and showing signs of distress. This is the finder at the start of
stripping. |
The finder scope stripped down. Note that the end plate
that holds the rear optical assembly is brass. The main tube is
aluminium. |
It was hard to mask the finder as it was tough to get
masking paper inside over the threads. In the end I settled for rolling up a
newspaper, putting masking tape over it and inserting it into the finder. This
also made a convenient handle to hold the finder by during
painting. |
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The finder was repainted with three coats of Rustoleum enamel paint
to provide a hard, durable finish. |
Note: Enamel paints take a long time to cure and fully harden. You
need to allow at least 7 days and mnore like 21 days before the paint is hard
enough to accept rough handling. This will depend on ambient temperature and
humidity of your location. |
Note: before repainting the exterior of the finderscope tube you may
wish to apply some blackboard paint to the inner part of the tube. If you do
this do not paint over any threads inside the tube. |
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Stage 3 - Stripping and Rebuilding the Finders Rear Optical
Assembly |
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The finders rear optical group/eyepiece is placed on a
soft surface. |
Remove the eyeguard by unscrewing it from the main unit.
This can be cleaned with soap and water. On this type of plastic you can also
use a small amount of toothpaste to bring it back to a shiny
condition. |
Loosen off the three small set screws around the knurled
section/focuser grip of the eyepiece assembly. |
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With the three small set screws slackened off
sufficiently the knurled section of the eyepiece will come away
easily. |
The two components left are the main lens group to the
left (brass coloured) and the reticule assembly to the right (black coloured).
The brass sections simply unscrews. You can see that there is almost no grease
left in this assembly plus there was a sharp piece of brass in the threads
which was causing the focuser to feel and sound terrible. |
The main lens element and the reticule element were
thoroughly cleaned with a lint free cloth and isopropyl alcohol to remove the
remaining grease and to clean the lenses before being flushed with distilled
water and left to dry. As ever Isopropyl Alcohol and distilled water are your
friends. |
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Once completely dry and with the lenses checked the
brass part containing the lens elements was smeared with lithium grease and any
excess grease removed with a paper towel.. It was then carefully
assembled. |
The lens element and reticule element
reassembled. |
Now the knurled component/focus grip is slipped over the
assembly and.... |
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The three set screw tightened. You need to work around
these in turn with a bit of tension added to each one to keep the assembly
square to the optical elements. |
Finally the eye guard is replaced. |
The finished assembly is now stored safely pending
completion of the stripping and repainting of the optical tube. The unit now
works smoothly. |
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Stage 4 - Rebuilding the 6x30 Finder |
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Once the enamel paint is fully dry and cured the
finder scope can be reassembled. First re-attach the finders collimation rings.
Be careful because the thread in these rings can be easily stripped and make
sure the grub screws are located into the indentations in the finder scope
tube. |
Now replace the rear plate to the finder scope.
This should screw in easily. |
Tighten down the small grub screw that retains
the rear plate. Do not overtighten. |
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Here is the rear optical assembly ready to be
reinstalled. |
Gently screw the rear optical assembly into the rear
plate of the finder scope. |
Tighten down the rear assembly gruub screw on the
rear plate of the finderscope. Do not overtighten. |
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Carefully replace the primary optical element to the
front of the finder scope. This needs to seat a little way down the
tube. |
Now tighten down the main optical element grub screw. Do
not overtighten. |
The finished finderscope looking (and working) as good
as new. |
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BACK TO THE
TAL RESTORATION GUIDE MAIN PAGE |
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