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Need Help With A Nikon Model G

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#1 abrogard

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Posted 07 August 2017 - 04:09 PM

My Nikon Model G has developed a 'sinking stage'  - the stage will not stay put but slowly descends.

 

Apparently a fairly common fault.

 

I am told there's usually a mechanism by which one can tighten up the focusing mechanism and stop this.

 

In some instances by releases the centres of the focusing knobs and turning the knobs against each other and then retighten.

 

I have released the centre of my right hand knob but the left will not release and it is not the same as the others.  It has a 1mm dia circle cut out of it near the edge and this makes me suspicious that it may be a pin in there simply to prevent releasing it.

 

Nikon, amazingly and disappointingly would not help at all.

 

And nor have I been able to find anything elsewhere.  Though there's lots of people know of the old Model G and value them as good instruments knowledge of how to fix this thing is not so widespread.

 

Simple information as to how the Model G was 'retensioned'  would be good.

 

If anyone can help at all?

 

:)

 

 



#2 Blind as an Eagle

Blind as an Eagle

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Posted 11 August 2017 - 11:03 PM

Abrogard, I would have liked to helped in some way, but researching your model at the few sources of information I could locate showed that you had already looked there.

 

Seems like the good news was that most parts of the type G are interchangeable with the stereo or binocular version, type S.

 

Bad news was, the recommended site Microscope Solutions  (?) has or had a kit to repair the issue. For just $650.00 US. 

 

It seems to me that this is a very high price for an instrument owner to pay for correcting the IMO bad design choice of using plastic materials in those scopes.

 

Questions: 1). Is there any area of the frame where you  could drill and tap a hole for a bolt or screw which could be carefully tightened against any part of the focus mechanism to hold it in place? 2). Can you even attain focus at all, due to the broken part?

 

# 1 would be my approach to restoring focusing functionality, if at all physically possible.

 

Regards, Rich

- - - - - - - -  - - - - -

Bausch & Lomb Stereopod 2, a less common, fixed power version of the B&L Stereozoom, with 2x objective and 10x Widefield eyepieces from an American Optical Cycloptic scope.



#3 abrogard

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Posted 12 August 2017 - 06:12 PM

Hello Rich,

 

and thanks for your efforts on my behalf.

 

Yes, I can focus it.  By packing plastic foam pads underneath the bit that goes up and down I provide enough resistance that it is able to stay put - and still enable me to move it down more because there's not enough bounce in the plastic to push it up.

 

Bit cumbersome and temporary - the foam slowly collapses and gets less able to do the job.

 

But yes, I can do some work with it.

 

I intend to write to Nikon management.  I think they'd not approve of the response I got from the company.  That was:  Receivers of my request forwarded to the Service Dept.  the Service Dept said firstly they knew nothing about the G  and secondly (after a response from me) that I surely wouldn't expect them to service a machine 40 years old?

 

I think that's right out of court.  And I'm hoping to get through to management with that simple query:  how was the focusing tensioned?   What is the purpose/use of the indents in the focusing knobs?

 

I'll give you a link to pictures,  FYI.

 

http://imgur.com/a/Xmkc9



#4 abrogard

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Posted 24 August 2017 - 04:50 PM

I'll post the results of my endeavours:

 

It is all fixed.

 

I finally got through to a helpful man in Nikon Instruments.  Got there by posting Tweets on Twitter.

 

He sent me a user manual.

 

It said contra-rotate the adjusting (focusing) knobs.  Without needing to take out the centres or anything else at all.  Just do it.

 

I tried and they wouldn't move.

 

So finally I decided to apply some force and risk breakage.  I got two multigrips on the job and tried.

 

A sudden 'ping' and they shifted quite a lot.

 

Tried the mechanism and it was tight.  Too tight!

 

Moved them back again a bit - moved easier this time and I was able to control how far they moved - and the mechanism is now good.

 

The stage does not 'sink' any more.

 

That wonderful old scope is working well..

 

So for anyone searching the web with the same problem here's the answer.

 

Thanks everyone for their interest.

 

:)


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