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Steve_s
Tinkerer
Username: Steve_s
Post Number: 16
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 06, 2006 - 09:23 am: | 
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I am trying to dismantle a Trioplan 100mm f2.8 pre-set lens with Exakta bayonet (bright aluminium). It looks as though you have to start from the front. The assembly consisting of the hood and the serial number-ring unscrews easily freeing the pre-set ring, and the front element assembly unscrews exposing the diaphragm.
The only thing now unscrewable is the single grub-screw on the sleeve which has the diaphragm index mark, and taking this screw out does not seem to free anything at the moment.
I don't want to force anything in case I damage the helical sliders. Does anyone know where I go next - how does the diaphragm barrel come out? There are no slotted rings, or anything else, removable at the back, as far as I can tell, apart from one retaining the rear cell.
I could upload an image if it helps. |
Steve_s
Tinkerer
Username: Steve_s
Post Number: 17
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 06, 2006 - 03:08 pm: |
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Think I've done it! Immediately in front of the bayonet is a conical section which appeared at first to be part of the focus-mount. This turned out to be an unscrewable cover and when removed with a friction tool 3 screws are revealed which enable the lens mount to be removed (careful not to lose 2 little springs!).
Will continue tomorrow when I have more time, but I'm pretty sure it should be straightforward now. |
Steve_s
Tinkerer
Username: Steve_s
Post Number: 18
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, November 07, 2006 - 09:30 am: |
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Almost made it, but now I'm completely stumped. The focus mount and helical came apart easily, but I'm now left with what you see in the picture and I can see no way of removing the diaphragm barrel.
With its grub-screw removed the sleeve "B" will unscrew to the rear by just 1/32" and then jams very convincingly. In any case, its inside diameter is smaller than the helical so it could not come off that way. The inside diameter of the diaphragm ring "A" is smaller than a diameter on the diaphragm barrel so neither "A" or "B" can be removed until the diaphragm barrel is out. There is no locking-ring to the rear or to the front or access to any screws or pins that might free it.
I tried to dismantle the diaphragm in-situ in case this revealed anything, but the actuating ring does not want to come out with its operating pin in place, and of course you cannot get this out until you've shifted "A"!
The 135mm Meyer Primotar looks as though it has a very similar construction to the Trioplan. Maybe someone has stripped one of these?
Any ideas anyone?
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Steve_s
Tinkerer
Username: Steve_s
Post Number: 19
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 09, 2006 - 04:20 am: |
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Got there in the end, so in case anyone else needs to go down this road, this is how it goes: -
Spent several hours yesterday fiddling with what is left of the lens. I eventually decided from the little I could see, that the helical inner must simply screw on to the back of the diaphragm barrel (helical outermost). I thought this was unlikely on two counts: Firstly, there would be no way of positively fixing the diaphragm assembly in line with the focus mount - it would have to be arranged by selective assembly of components at the factory. Secondly, there would be nothing except the tightness of assembly to stop the assembled lens coming apart at the helical. Needless to say it did feel VERY tight!
This morning I got out the blow-lamp and heated up the helical gently until it was just not quite too hot to touch. This did the trick and it unscrewed at the first try. This, of course, leaves "B" in the picture free to unscrew to the rear, and "A" free to slide off once the diaphragm actuating pin has been removed. |
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