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John_s
Tinkerer
Username: John_s
Post Number: 43
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 15, 2011 - 10:20 am: | 
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I've got one of these, which screws on to the eyepiece of an F2, FE etc to give a right angled view. The problem is that the rotation of the finder between vertical and horizontal positions is loose, that is it doesn't stay in position but flops down under its own weight. Does anyone know if this can be tightened? I notice that in the barrel which screws on to the camera there is a hole through which a single screw can be seen at a certain angle. This doesn't seem to be an adjustment however. Any ideas please? |
Glenn
Tinkerer
Username: Glenn
Post Number: 890
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 15, 2011 - 12:34 pm: |
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I have not handled this particular model, but from studying available pictures on the internet a simple remedy seems possible.
Unless the rotation is controlled by a spring wave washer, I suspect that the silver barrel was originally packed with a thick silicone grease to restrain movement. I suggest that the single screw you have found is a grub-screw that retains the barrel onto the body of the finder. If grease was originally used, removing the grub-screw should allow you to pull off the barrel and expose the bearing surfaces that need coating with grease.
On all the finders using a spring wave washer to apply friction that I have examined, one has to remove the bottom section of the finder body to expose the threaded retaining ring or circlip. This bottom section holds the mirror or prism, and the pictures of the DR3 clearly show at least four cross-head screws holding this bottom section (two on each side are most obvious, but there could be a couple on the face on which the barrel is located.)
I think that you should easily be able to remove the required bits to facilitate a repair, there is nothing to go out of adjustment - so long as you do not mess with the focus/dioptre mechanism in the top half of the finder body. |
John_s
Tinkerer
Username: John_s
Post Number: 44
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 15, 2011 - 02:30 pm: |
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Glenn this is understood, thank you for your help yet again.
I will have a look and report back when I've got a minute... |
John_s
Tinkerer
Username: John_s
Post Number: 45
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 21, 2011 - 09:44 am: |
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Well I removed the grub screw, but the barrel did not want to slide off even with a little force. What I then did is going to sound ugly, but it actually worked. I found a self tapping screw just larger than the hole and screwed it in, thus forming the beginnings of an internal thread. I then found a small bolt about the same diameter and screwed this into the hole to improve the thread. I then found a small cylindrical piece of brass which was fitted to the (shortened) bolt to make a little thumbwheel. I can now lock the DR3 in any position just by tightening the thumbwheel. There's no damage to the unit itself apart from the thread which is hard to see. |
Glenn
Tinkerer
Username: Glenn
Post Number: 893
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 21, 2011 - 12:43 pm: |
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Well thought out, nothing wrong in what you did and the unit is now fully useable without needing three hands.
Your comments about the grub screw are puzzling - I wonder if there was a small friction 'pad' originally fitted in the bottom of the tapped hole that stopped the free movement? Has the unit been taken apart before and the insert lost, perhaps you will find a repair manual someday? |
John_s
Tinkerer
Username: John_s
Post Number: 46
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 21, 2011 - 01:05 pm: |
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The grub screw is very small - hard to see how a pad tiny enough to fit beneath it would have worked. There's no sign of it's having been dismantled. I guess it would have come apart - if I'd pulled hard enough - even then I would have had to find grease stiff enough to prevent the movement. |
