Author Topic: Howto remove locking in TBT?  (Read 3577 times)

Offline drew

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Howto remove locking in TBT?
« on: December 01, 2012, 06:16:18 PM »
One side of the Lionfish's Target Bearing Transmitter binoculars has had water in it for a long time. Decided it is time to fix it.

I have hit a snag in the disassembly required to get to one of the lenses that is so coated with crud you can't see through it.
There is a lock ring that needs to be removed to get at the optics. It is has about a a 3 3/4 inch O.D., and four slots 90 degrees apart for a lock ring wrench. I placed a screwdriver in one of the slots, and banged at it hoping to get the lock ring to turn, but no luck. If I bang too hard I will mangle the slots, which I don't want to do. I have also tried penetrating oil, but so far that hasn't helped. The threads are not rusty, so I don't think the ring is stuck because of corrosion.

Any idea where to get a wrench that might fit it? Or perhaps other ideas on how to get the ring to spin?

It is hard to see in the picture, but..
You can see what looks like a vertical pipe with a flange that has 6 holes. There are threads in the I.D. of that pipe. Follow the threads down into the pipe, the first object is the lock ring, it is about 3/8" tall. At about 45 degrees clockwise from due north is one of the notches for the wrench.
There is also a black lock ring that holds the lens in, that is isn't the lock ring or the lens that I am trying to get at. The lens that has the problem is at the eyeball end of the binoculars. The insides of the binoculars have to be removed to get at the inside side of that lens.

Thanx,
Drew

Offline Karen D.

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Re: Howto remove locking in TBT?
« Reply #1 on: December 04, 2012, 06:25:56 PM »
We've done some work on our TBT's so I asked my vols. I only heard back from one so far. If others have ideas I will pass them on!

I myself would most likely build a tool to fit the notches if I couldn't find one.
 
I doubt if the threads are left handed but it wouldn't hurt to shock the ring 'tighter' first. Sometimes a slight movement tighter can assist to remove stubborn fasteners. I have done this many times.
 
Phil

Offline Karen D.

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Re: Howto remove locking in TBT?
« Reply #2 on: December 05, 2012, 10:52:01 AM »
I agree with Phil--use the right tool. You might check with the optics shop at a major base like Pearl Harbor.  If no luck there, make a tool.
 
Pat


Hope this helps!

Offline Lance Dean

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Re: Howto remove locking in TBT?
« Reply #3 on: December 05, 2012, 02:47:04 PM »
Thanks for coming in with a reply, Karen. I surely have no idea.

Offline Karen D.

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Re: Howto remove locking in TBT?
« Reply #4 on: December 05, 2012, 07:26:09 PM »
I didn't have a clue either, that's why I asked my experts! :)

Offline pekelney

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TBT Manual Online
« Reply #5 on: December 05, 2012, 08:37:43 PM »
You may find the following manual useful:
http://hnsa.org/doc/pdf/tbt.pdf

Also, you are looking for a spanner wrench.  You might get lucky on the size.  They also make adjustable spanners, but do not try to use a punch and hammer.  You really need a spanner to open this kind of locking ring without breaking anything or stripping the locking ring.

rich
« Last Edit: December 05, 2012, 08:42:23 PM by pekelney »

Offline drew

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Re: Howto remove locking in TBT?
« Reply #6 on: December 06, 2012, 11:17:57 PM »
Thanx for the suggestions
>> but do not try to use a punch and hammer
Since I already tried the punch and hammer, and it didn't work at all, I can see this is a good suggestion.  I was careful (liucky?) enough that I haven't broken anything.

Also, I got confused when reorienting the unit for a better grip, and accidentally tried tightening the ring. That didn't free it up either.

Finding or fabricating a wrench looks like the next step.

I looked for a manual and failed, so I appreciate showing me the one at HNSA. I guess the binoculars are called telescopes. The TBT manual references pamphlet 1398, which would cover telescope repair. If I had that pamphlet, maybe it would show a drawing of the wrench.

Drew

Offline Paul Farace

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Re: Howto remove locking in TBT?
« Reply #7 on: December 16, 2012, 04:22:43 PM »
My best advice is not to try to do anything to the TBTs... about 30 years ago a vet with a high level of mechanical skill tried to fix this same problem... only to make matters far worse. This is like doing brain surgery on your kid. The TBT optics are nitrogen pressurized if I am not mistaken. We shipped ours off to a Navy optical shop several years ago and have checked on them routinely... (not happy about the time involved) and they are slooooooooooowwly being worked on (they say) when things get slow ... we can always trade time for moolaa.... (but this is pushing it :o???  Really, unless you need to shoot torpedoes, waiting until the right person with the RIGHT TOOLS presents itself, is the best bet.  They may look simple, but trust me, unless the person is an expert in optics (good luck finding one of those this side of Germany, Japan, or Kollmorgen!) you're asking for pain down the road.  Try to cultivate a contact at a major Navy repair or civilian service center... maybe (not tried this myself) one of the camera repair facilities in the USA might want to tackle this as a goodwill project (Nikon, Canon)?
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