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Status: Long, long time Contax and Yashica user; glad to be here and hope to contribute.
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on Apr 25, 2015 10:52:20 GMT
Posted: Apr 25, 2015 10:52:20 GMT
 I was so pleased to have found a 100-300 at a sensible price and looking forward to receiving this lens described as in 'excellent condition' BUT you've guessed it; not quite as described...
I know this is one of the gems in the Yashica range and have been trying to get one to test against the Zeiss version for about 6 months. So, after picking my way through the very well-packed parcel, the lens appeared and looked superb on first examination; clear glass, good focusing, just a little zoom creep in the mid-range...and then I tried to open the aperture fully. It can't get to f5.6, with somewhere between f8 and 5.6 as good as it gets....such a shame. Then I spotted something even worse - an attempt had been made to remove the mount - presumably to attempt a repair - and the person had completely stripped the cross-heads of 2 of the 4 retaining screws. So I can't even get to the aperture assembly to see where the problem is - there's no way in from the front on a lens of this size.
Anyone here had any experience of dealing with stripped Yashica mount screws? Is it just me or do Yashica use a softer metal for these little silver screws as the ones in Zeiss mounts don't get stripped so easily (except the silver screws on the Mutars!)? I'm beginning to believe that they must use some special equipment to remove them.
So, unless you guys know someone that can help with removing the mount, my hunt for a 100-300 may have to continue a little longer....
Graham |
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on Apr 25, 2015 15:32:59 GMT
Posted: Apr 25, 2015 15:32:59 GMT
Now, that's too bad, Graham! I can't actually answer your question, having no experience with the screws you mention, yet I wonder if you couldn't scratch new slits into the--presumably rather soft--metal of the screw heads with a pointed arbor (I'm not sure if that's the correct expression for those thingies that are often included with precision screwdriver sets). I once managed to do a similar thing with the remaining end of a broken screw holding the rewind lever of a Kiev 60, just enough so to be able to insert a small screwdriver and get the bastard out:  Of course, this doesn't solve your next problem, that is, where to get replacement screws... Michael |
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Status: Long, long time Contax and Yashica user; glad to be here and hope to contribute.
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on Apr 25, 2015 17:26:45 GMT
Last Edit: Apr 25, 2015 17:28:48 GMT by biggles3
Now, that's too bad, Graham! I can't actually answer your question, having no experience with the screws you mention, yet I wonder if you couldn't scratch new slits into the--presumably rather soft--metal of the screw heads with a pointed arbor (I'm not sure if that's the correct expression for those thingies that are often included with precision screwdriver sets). I once managed to do a similar thing with the remaining end of a broken screw holding the rewind lever of a Kiev 60, just enough so to be able to insert a small screwdriver and get the bastard out: Of course, this doesn't solve your next problem, that is, where to get replacement screws... Michael A good thought! I also have a small electrical drill that model engineers use and have been thinking about scoring the top of the damaged screws to allow a simple screwdriver to get enough leverage to turn them; I would prefer to try that rather than drill out the heads to release the mounting plate as that carries the risk of leaving the threaded body of the screw in situ if I can't twist them out with pliers. The problem is that it's physically straightforward with a small lens but much more difficult with a long zoom - a little ingenuity may be required to secure the lens while trying to drill.... Oh yes, those replacement screws: mercifully, a US Ebay seller sold me a selection of Contax/Yashica small screws from a defunct repair shop though I have no idea right now where I put them all!
Thanks again for the suggestion - definitely worth a try.
Graham
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on Apr 26, 2015 0:05:23 GMT
Posted: Apr 26, 2015 0:05:23 GMT
Japanese camera manufacturers at some point switched to a home spec screw design (JIS) which looks like a Phillips, but is not. Micro-Tools sells the drivers in sets. When someone uses a Phillips screwdriver on these, stripping usually occurs. Also, some manufacturers put glue on the screws, so that has to be softened up before removing them.
You can use a left-handed drill bit to remove broken screws, Graham. Just start with your drill on Reverse, and as the bit digs into the screw, it will back right out. If it isn't glued in.
PF
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Group: Moderator
Post: 2,040 (563 liked)
Join date: April 2014
Status: Long, long time Contax and Yashica user; glad to be here and hope to contribute.
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on Apr 26, 2015 1:16:27 GMT
Posted: Apr 26, 2015 1:16:27 GMT
Japanese camera manufacturers at some point switched to a home spec screw design (JIS) which looks like a Phillips, but is not. Micro-Tools sells the drivers in sets. When someone uses a Phillips screwdriver on these, stripping usually occurs. Also, some manufacturers put glue on the screws, so that has to be softened up before removing them. You can use a left-handed drill bit to remove broken screws, Graham. Just start with your drill on Reverse, and as the bit digs into the screw, it will back right out. If it isn't glued in. PF I live and learn - left-handed drill bits, what will they think of next! Now, all I have to do is find a left-handed drill... 
Thanks for the suggestion and also the clarification on the JIS screw design - it explains a lot!
I feel more confident now that I will be able to disassemble the 100-300 mount and see if the faulty aperture assembly can be rectified. So, instead of Contax or Yashica gear, I'll be buying two 1.75mm l/h drill bits, a reversible drill and a set of small scale JIS screwdrivers... Makes a change.
I can also finally sort out the damaged mount and retainer on an old Contax Mutar I....marvellous. Thanks again PF.
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I was so pleased to have found a 100-300 at a sensible price and looking forward to receiving this lens described as in 'excellent condition' BUT you've guessed it; not quite as described...
