Stuck Lens Cap

[Andrea B.]

I have a stuck lens cap.
This is a Nikon new style LF-4 lens cap which is stuck onto an F-mount helicoid.
I can't for love-nor-money figure out why this cap is stuck. 

So what to do? I'm almost to the point of attempting to break it off. I need to use the helicoid.

Putting the helicoid & stuck cap into the freezer for 5 minutes did not work.
Spraying WD-40 into the cap (through the helicoid) did not work.

What should I try next?? Heat? Hammer? Ice Pick? Pliers? Vise?

[Bjørn Rørslett]

A filter vice (found on eBay for a few $$) is very helpful to remove stuck filters or hoods. In a pinch, use some rubber (cycle tubing, or rubber from a lens focusing collar) to give better grip.

If you want to use differential thermal expansion, we're talking about hours in the freezer not minutes.

The ultimate solution is here, as elsewhere in the world of nerds, judicious use of a hammer. Only use if everything else fails and you are getting desperate.

[Erik Lund]

Is it part of a 'hidden camera show'? 

Are you able to push/slide it up down? Looking from the rear push 12 o'clock then-  6 o'clock,,,

[Erik Lund]

Only thingh that could catch the rear cap is the 'end stop' mounted on all F-mounts at 6 o'clock,,,
so slide it down and twist while pushing the cap onto the lens

[Andrea B.]

The cap would not move in any direction - up/down, back/forth, clockwise/countercw. Finally I got a rubber mallet and bonked it twice (along the 6/12 axis). Then it came off! Of course, at that point the cap might finally have been ready to come off. So I'll never know if it was the freezing, the WD-40, the rubber jar tool or the mallet bonk which convinced it to loosen.

When looking at the cap, we turn it counter-clockwise to fasten it. When doing that, the cap seems to go a little further in the counter-clockwise direction that I would normally expect. So I don't know if this is due to this particular cap being a little "out of spec". Or perhaps something, say the helicoid F-mount, has cut into the plastic, made a groove of some kind during rotation of the cap which might have caused the cap to stick too tight.

The screw-stop on the helicoid (opposite the mounting dot at 6'oclock) does not seem unusual in any particular way. But I don't have a way to know if it perhaps protrudes too far.

Anyway, all's well that ends well.
Thank you both for your help. 

[Erik Lund]

We have a saying at work; If a hammer doesn't work - Go get a bigger hammer,,, 

[richardHaw]

 

[charlie]

Finally I got a rubber mallet and bonked it twice (along the 6/12 axis). Then it came off! Of course, at that point the cap might finally have been ready to come off. So I'll never know if it was the freezing, the WD-40, the rubber jar tool or the mallet bonk which convinced it to loosen.

Once upon a time I was rebuilding a vintage 1953 fire truck engine and one of the pistons was seized in the block. I tried everything I could think of for a week to get the thing loose. Hammers, presses, torches, freezing it, chemical soaks. Finally what ended up breaking it loose, I poured a bottle of coca-cola in the cylinder and let it sit over night. Next day it came right out.

So next time you find something stuck, just pour some coca-cola on it :-)

[David H. Hartman]

So next time you find something stuck, just pour some coca-cola on it :-)

Will Pepsi or Dr. Pepper or Royal Chrown Coke-a-Cola work was well. What if you can't get the real thing in your country? Wait around here Home Depot sells Mexican Coke. I'm pretty sure that's made with Real Cane Sugar from Cuba. 

Dave

[David H. Hartman]

Will a forensic investigation of the cause of this stuck cap dilemma follow?

[Andrea B.]

I dusted the lens cap for fingerprints but they were all mine! 

Actually I think the helicoid flanges seem to have cut a little bit into the plastic of the inner vertical 'leg' on this new style Nikon lens cap. It looks like the plastic might have been slightly crushed at the top of one of these legs. So probably the helicoid stop screw or flange got stuck in this area.

The inner construction of the new style and old style Nikon caps is (obviously) the same. But perhaps the plastic isn't the same?

I refitted the helicoid with an old style cap and it has a looser fit, i.e. normal. I think the stuck cap is going to go to the recycle bin. I do not want to risk having to hammer that darned thing off a good lens should it get stuck again. The $20 helicoid was expendable.

*****

I buy a couple of those Mexican Coca-Colas every now and then, and they are indeed made with real sugar. I was surprised that they had a different taste - less sweet, but a better sweet.

[Erik Lund]

Yes the new Caps are softer plastic,,,

[Andrea B.]

Aha!!!!
I think I will look for a few of the old ones before they are all gone.

[Erik Lund]

The difference is very slight, I actually prefer the new ones,,,

The problem you encountered is due only to the dimensions of your 'not-original' F-Mount.

[David H. Hartman]

I think I prefer the new ones also as the old ones seem to come off in the bag too easily. That could change if I have to graduate to a 3 Lb. maul (1.4k). Why of why is the USA still stuck with the old weights and measures? So stupid.

I hate most of all cars with fasteners that are both SAE and Metric. Give me one or another. I have both tool sets.

Dave