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Waynemel
Tinkerer
Username: Waynemel
Post Number: 434
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 04, 2013 - 07:12 pm: | 
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I am trying to disassemble a Kiron 28-85 and have reached a roadblock. The screws that guide the zoom (the ones with the nylon bushings) are proving very difficult to remove. I have tried acetone, penetrating oil, heating with a soldering iron, dinner and a movie and they still won't budge. Does anyone have any other tips? I have damaged the screw heads a little in my attempts ( they are slotted screws (why did they used slotted screws anyway?)), but they should still come out.
I am at the point where I might scrap the whole lens, but I don't want to give up! |
Gardener
Tinkerer
Username: Gardener
Post Number: 6
Registered: 02-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 04, 2013 - 08:35 pm: |
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Acetone. Wait. Try. More acetone. Wait. Try again. Repeat in the same order. I hate Kirons, they are a total PITA to work on. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 436
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 04, 2013 - 08:50 pm: |
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I tried acetone by applying it several times a day over a few days. I guess I could continue... |
Chris_sherlock
Tinkerer
Username: Chris_sherlock
Post Number: 68
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 04, 2013 - 11:02 pm: |
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The standard technique is to borrow somebody else's good screwdriver, and take your favourite small hammer, and give the screw a good thump while maintaining some torque on the screw, just like getting the screws loose on a motorcycle engine.
Regards, Chris |
Gardener
Tinkerer
Username: Gardener
Post Number: 7
Registered: 02-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 05, 2013 - 09:28 am: |
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Kiron engineers may have saved 15% or more on grease, but they sure went all out with threadlocker. I was working on Kiron 28/2 a few weeks ago, took me 4 days to pry the front group off, and I'm trying to gather courage to go after 28-105 I've been looking at for months now. The damn thing is, I just did the aperture on Vivitar Series 1 28-90 - it takes less than 5 minutes to take the aperture assembly out and in a couple of hours it was back together again. Probably a better lens than you Kiron too.
Anyway, what I was going to say - apply acetone liberally, and don't wait for it to dry, otherwise the threads will just relock. Also, consider using MEK - it has higher boiling point and won't evaporate as fast. |
Thepurush
Tinkerer
Username: Thepurush
Post Number: 89
Registered: 01-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, April 05, 2013 - 09:39 am: |
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Exactly, that is the right way. I have sucessfully used that method on several ocations. But no use if u dont use the correct scredriver. The first time I was stuck, un able to open a screw on mamiya camera I used this method. But my screw driver was modified to fit in to the scre perrfecly square. The japanese screws are a bit differcnt and most scres drivers availble wont fit in them sqarely, meaning making full contact in thier slots, may be the angle matters. I have one screw driver specially modified to deal with such situations and it never ditvhed me. I had cut off the shank of a normal jewellers screw driver heated the tip and while it is hot I hammered it in to a scre fitted in to a wooden plank. After several attempts the screw driver took the shape of the slots in the screw.
Here is my screwdriver.
The one on the left is to show how it was before. In had cut off the shank so I can handle during hammering as well as I added thicker plastic handle for a better grip. The handle was from a disposable razor. |
Waynemel
Tinkerer
Username: Waynemel
Post Number: 437
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 06, 2013 - 09:25 am: |
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Gave up!
It's now in the spare parts bin.
Thanks for all of the suggestions. I will keep them in mind for next time (which I hope never comes!) |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 249
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, April 07, 2013 - 09:11 am: |
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Hey Wayne, if it's any consolation, you can often pick up a Vivitar Series 1 28-90 for a paltry sum on eBay. Ignore the overly-optimistic and inflated Buy-It-Nows and go for an auction. I picked up a clean one in Nikon mount a couple of years ago and paid about $25 for it. Fortunately, it didn't require any maintenance. As Gardener mentioned (and as I would affirm), it's probably a better lens than the Kiron 28-85 anyway. This one is my second. I owned one in Canon FD mount for years and it really did take very sharp, well-saturated and contrasty pics. |
Gardener
Tinkerer
Username: Gardener
Post Number: 9
Registered: 02-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, April 07, 2013 - 01:14 pm: |
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If you go that way, make sure to get good pictures - distressingly large percentage of Series 1 lens bear signs of clumsy attempts at repair. |
