I'm getting pretty good at this lens CLA business, but you can't do a CLA if you can't get inside.

I have a Zeiss 85/1.4 Planar (MM) in desperate need of a cleaning, and it's making me insane.
This is my first Zeiss, but it doesn't look significantly different from Nikons, Minoltas, etc.

The name ring is off, and the two retaining rings are easily accessible, but the bloody things won't budge. I have a really good grip with my spanner, and literally have put my entire strength into it. I tried clockwise and c-clockwise.

I tried the inner (cell) ring as well. - just as tight.

I tried heating it with a hair dryer (not too much, though)

In desperation, I even sprayed some Tri-Flow into the threads (I'm going to clean it, anyway) but it's as if those rings are epoxied in.

Is there some special trick with this lens?

Any ideas at all?

Acetone. It runs, so be careful how close it gets to glass. Acetone should dissolve most sticky stuff, very quickly.

Like to here some more rebuild stories...

Interesting idea, Jim.

So, I assume that there's no trick, no hidden set-screw or something, right? I didn't think there could be, but best to ask first.

You could definitely be right that there's some solidified goo in the threads. This is one of those lenses that got a ton of humidity, and in desperation to stop any fungal growth (before I owned any tools) I put them all in a low-heat oven. This lens probably had something on the threads which melted & solidified.

I didn't want to use that kind of heat again. Bad for the rubber.

I'll have to pick acetone up tomorrow and give it a go.

Thanks for the excellent idea.

Well,

no good with the acetone. I let it sit for about 5 minutes. I'm afraid to use more, or for longer, because it might desolve something inside the lens. (No idea if it can, but why take a chance?

Finally put it back in the oven. 200 degrees for 10 minutes.

those rings STILL won't budge. I actually hurt my arm, with all the force I used. The spanner didn't slip, but those bloody rings just won't turn.

I don't get it.


All I can do now is try to go in from the back, which means pulling out the aperture assembly. - and I still probably won't get to the watermarks.

Ughh.

Take a photo for further examination by us ghouls, on halloween.

I have not worked on Zeiss b4, but the retaining rings on old Pentax lenses were often threadlocked. Acetone should work, but only b4 it dries, and it dries fast. You can also custom make tools for better grip and less tool marks, and I hate tool marks.

Questions on acetone:

Can it possibly remove coatings from a lens? I'm referring to lenses no older than, say 1980.


Is there anything inside a typical lens that can be dissolved by acetone?


(I may have to literally dunk the lens, or maybe pour in the acetone from inside, after removing the aperture assembly)

wlachan wrote:
You can also custom make tools for better grip and less tool marks, and I hate tool marks.


Any pics or instructions on this?

The thing that would help the most is some kind of vise to hold the lens. However, my personal efforts have failed, as too much pressure starts to bend the lens inward. It's pretty scary.
I can't seem to find a solid area to clamp.

Per this article, http://homepage.mac.com/fwstutterheim/rugarchives/1998-04/00382.html, you need special wrenches to disassemble a Zeiss lens.

James. that guy isn't talking about a "Zeiss-specific" special wrench. It's just a spanner wrench, which is used for all lenses (and any other item with locking rings.)

As a Pentax user, I have only used acetone on Pentax SMC & HOYA HD/HMC/DMC/HMC SUPER w/o any ill effect at all, that's including any K mount SMC lenses since the 70's. Since T* was jointed developed with Pentax SMC, perhaps they aren't that different? As to wrenches, manufacturers don't use one-size-fit-all wenches. Just see what Canon use on their YouTube videos to get an idea. Since we cannot hope to get those perfect fit wrenches, you can only use your imagination to custom made the best you can come up with. A trick I use is to put a piece of dental rubber between the retaining ring and the wrench to avoid tool mark, especially when you need to apply force. Experience tells me any retaining rings should not be forced open. If they didn't come off with reasonable force, I know I was missing something. For your problem, you might use a small dropper and add a few drops of acetone just around the thread of the retaining ring. You might need to do this multiple times before the cured threadlock was soften enough to release the retaining ring. However, since I have never repaired any Zeiss, I have no idea how they were put together. In any case, don't force or soak anything.

wlachan wrote:
Since we cannot hope to get those perfect fit wrenches, you can only use your imagination to custom made the best you can come up with. A trick I use is to put a piece of dental rubber between the retaining ring and the wrench to avoid tool mark, especially when you need to apply force. .

Excellent idea! (or maybe blue tape)

Wish I had thought of that before I started. There's now basically no anodizing left on the filter threads in those two places.

Glad to know that the coatings are probably safe. Thanks.