Vintage Gear Surprise, pre AI.

[Erik Lund]

Btw. The stripped screw; clean the burrs away carefully so the tip of the screwdriver can get fully down into the head and try again, with:
Downward force,,,
Standing up,,,
Solid table,,,
Wrist straight,,,
Rubber working gloves,,,


This always works!

[Matthew Currie]

I would add (as a general mechanics' rule of thumb) that if you are dealing with a very stuck screw, it is often better to alternate on and off rotation initially, to get it unstuck.  If you just yank in the loosening direction, you're more likely to strip the head or shear the fastener, but if you go back and forth, seemingly in vain, it will often eventually break loose.  Remember that any movement at all is basically a victory.  Be patient.

[Eb]

I've lost count of the number of times I've found myself in the same situation.
Thread lockers are basically thermoset plastics, so as others have suggested - acetone or heat are the best way of loosening the bond.

As far as removing the screws; holding the screwdriver by hand is clumsy & awkward with the very real risk of damaging the lens or yourself.
I do the job in a drill press.
First remove the power from the drill in case it accidentally starts.
I use a screwdriver that I have removed the handle from. I then insert the screwdriver's shank into the drill chuck.
Rotating the spindle feed (which lowers the drill chuck/spindle) will force the screwdriver into the screw's head.
Using a leaver inserted into the drill chuck allows a large amount of torque and the spindle feed mechanism allows a large amount of axial force to be applied to the screw's head.
The lens is generally held by hand.
I have never needed heat or acetone to break the thread locking bond nor have I ever broken a screw with this method. I have certainly broken many when trying to do it by hand though.
With this system, it allows you to gently reverse the torque, back & forth, until the bond breaks..............without damaging the screw's head or the screwdriver's tip.

That is ingenious!  I'll investigate if I can get enough throw for the 400mm on my table top press - though I doubt it will be enough.

[Eb]

i usually let the solvent work on it before dinner and get back to it after I had my meal and jaegermeister
sometimes, I would have it the overnight

Frankly, I never had the screw problem after buying the long-shafted VESSELs. only very rarely do i get a problem like that

My rarity has occurred, unfortunately!  I started the acetone treatment yesterday and have continued many times since.  Perhaps today will be my day!  Seems like the acetone evaporates before making its way down to the threads.  On the one screw I extracted, the thread locking compound was way down nearer the bottom of the shaft.  When, at one time, you had resorted to using a mini butane torch, how long did you apply the flame?

[Eb]

Wery sad to hear! Try again! You need downward force!!! And Rons solution is a workaround if your not good with your hands.


Usually there is still enough left for the screwdriver to grip on to,,,

Yes, my hands do shake with the creep of age! 

[Eb]

Only the head should be drilled!!! Leave the threads to grip on too.

Absolutely!  Use of the mini extractors is a back up plan as it will take several weeks for their arrival.  I'll avoid drilling into the screw shank, if it comes to that.  Thanks.

[Eb]

Btw. The stripped screw; clean the burrs away carefully so the tip of the screwdriver can get fully down into the head and try again, with:
Downward force,,,
Standing up,,,
Solid table,,,
Wrist straight,,,
Rubber working gloves,,,


This always works!

Erik, I thank you for your encouragement and will certainly work on my technique.  I was hoping for one more try on the reamed out screw head but not until I have successfully loosened the others.  If they do not budge, it is unlikely I will be successful with the damaged one.  I'm sorely tempted to use a mini butane torch.  Why, oh why, would Nikon use a high temperature thread locker on such fine screws?  I have not yet checked if the repeated acetone treatments and the overnight wait has done any good.

[Eb]

I would add (as a general mechanics' rule of thumb) that if you are dealing with a very stuck screw, it is often better to alternate on and off rotation initially, to get it unstuck.  If you just yank in the loosening direction, you're more likely to strip the head or shear the fastener, but if you go back and forth, seemingly in vain, it will often eventually break loose.  Remember that any movement at all is basically a victory.  Be patient.

Mathew, this is essentially what I have been doing and paying attention to the flex in the screw driver shaft.  It is disappointing that nothing has budged (other than the first screw.)  The downside, of repeated tries is cumulative wear on the screw head.  These things are really stuck!  Moderate heat from a soldering pencil, and, indeed, someone had recommended using a hair dryer, does not work to loosen the thread locker.

[Eb]

An interesting point shown on the website of a company that makes liquid threadlockers -

Q3: I cannot get an assembly apart where a threadlocker was used. What solvent will break the threadlocker down?

A: No solvent will wick into the joint to break the threadlocker down. This is either hand tool removable at room temperature or if not, it requires high temperatures of 450-600°F to separate parts. The products are thermoset plastics in the cured state that soften at higher temperatures. Thus, you need to disassemble while at the higher softening point temperature. Do not let this cool down first. Otherwise, it will resoldify. Solvents like methyl ethyl keytone and methylene chloride can be used for clean-up of residue only after disassembly.

There's the nub of it!  Moderate heat will not work (my soldering pencil max is 400 F, and the acetone is not making it down the screw threads, so far.  Here comes the torch, if I can get one today.

[Eb]

Hello, I don't think this will work. It's too big (1.5mm) and is made for wood screws.
the 1mm ones do cost a bit (pun intended), I got mine for $10USD for the bit alone.

Why won't they ship to Canada? Can you investigate? If we know the reason then maybe I can get that myself and ship it to you personally.

Perhaps you are right, but the set does include the 1 mm. drill size.  I assumed that the one you recommended was the same as the smallest (1mm.) one in the set.  Not reading Japanese, all I could see is the mention of 1 mm. on the package.  I inquired from Rakuten and confirmed that the dealer will only ship domestically.  Believe it or not, I get the same thing from lots of US dealers who can't be bothered to ship abroad.  One solution they suggest at Rakuten is trans shipping to a domestic dealer who will then repackage and ship abroad.  By that time, the $13 CA item may well cost as much as the ebay dealer wanted $77 CA.

The point of the intended design for wood screws is well taken.  But, I was reassured when I looked at the illustrations on both packages which showed exactly the same pictures based on wood screw examples.  So I can be forgiven for my conclusion that they were the same product. 

I appreciate your kind offer to make the purchase for me, Richard!  However, the one is ordered and I will wait for it, for now, and see what's up.  Maybe luck is with me today.  I will try the butane torch method of desperation.

[Eb]

An interesting point shown on the website of a company that makes liquid threadlockers -

Q3: I cannot get an assembly apart where a threadlocker was used. What solvent will break the threadlocker down?

A: No solvent will wick into the joint to break the threadlocker down. This is either hand tool removable at room temperature or if not, it requires high temperatures of 450-600°F to separate parts. The products are thermoset plastics in the cured state that soften at higher temperatures. Thus, you need to disassemble while at the higher softening point temperature. Do not let this cool down first. Otherwise, it will resoldify. Solvents like methyl ethyl keytone and methylene chloride can be used for clean-up of residue only after disassembly.

Ron, your information, got me thinking about the acetone.  It evaporates so fast, would it really migrate down the threads?  Just to see how well acetone dissolves or degrades the thread locking thermoplastic, I placed the one extracted screw in an acetone bath for several minutes.  After drying the screw, the thread locking compound still persisted.  I could flake some off, but just a bit, with a fine point, so if the acetone degraded the plastic, it was minimal.  Acetone success, reported by many, may well depend on the product Nikon used at other time periods.

When celebrations are done, I will try your drill press method.  The lens is 26 cm.  The drill press throw is about 23 cm, with a small bit inserted.  I may be able to gain extra throw by clamping the base to the work bench and rotating the head assembly to the side.  Looking forward to the New Year to try this!  Happy New Year!

[RonVol]

Hi Eb,

In some way I'm not surprised by the result of the little experiment you did with the acetone.
I must admit that I have never used it as it never made any sense to me.............how it was supposed to make its way through the tiny gap of the assembled male & female threads..............and this gap now being filled with thread locker.
I looked through Loctite's entire product catalogue and they do not make a product that supposedly dissolves thread locking compound that has set. One would assume that if such a product could be produced, that Loctite would make it available in their product line-up.
But still; numerous people have claimed success with this procedure so I don't intend to argue with their positive results.

You may need to slightly modify the screwdriver's shank should the screw require a large amount of extraction torque. I have found that in some circumstances; the 3-jaw drill chuck has difficulty gripping the round, smooth shank. So I have had to grind by hand, 3 small flats (at 120 degrees) for the jaws of the chuck to grip on.

You'll find that having someone hold the lens for you is a great help.

In the past I have used a self-centering 3-jaw chuck off a lathe to hold the lens.............but not gripping the lens directly. I can explain how in another post if you like.

Don't forget to remove the drill from the power supply!

[Erik Lund]

....The downside, of repeated tries is cumulative wear on the screw head.  ......

If enough downward force is applied there will not even be a mark on the screw head!!! It will look mint,,,

[Eb]

If enough downward force is applied there will not even be a mark on the screw head!!! It will look mint,,,

Yes, that would make sense, but I'm far from perfect!    

In hindsight, the work bench was too high (or I have become shorter, this is true  )  I suspect that I am not able to maintain consistent downward pressure, as my hand starts to shake when I put it under stress.  Arthritis reduces strength.  Bad eyesight is also a source of frustration as it can't be corrected.  This may have had something to do with accurately gauging the screw driver head engagement.  I overlooked all these things, because in the past, these would not have been a concern at all.  So I was inadvertently sloppy!  However, my misadventure should not discourage anyone else from tackling a lens disassembly if they feel fit.  I can say, unequivocally, that I was given the best of instructions that most should be able to follow, flawlessly.

Unfortunately, I have become all washed up for this kind of thing.    But, whatever reason for my lack of competence, it seems obvious to me that Ron's method with the drill press will do the trick.  I still have to wait for a Moody driver blade without a handle, since I do not want to cut up my screw driver.  I'm sure to need it for screwing things back together.  (New screws are coming.)  The shipping of the extractor bit is delayed, because of holiday week in Japan.  So, nothing much will happen with this project for 3 or more weeks.  In preparation I have readied and adapted my drill press which is rated nominally at 8 inch (20 cm.) throw to be increased by approximately 10 cm.  I also have acquired a nice mini butane torch, should that be necessary.  When the time comes, my wife will hold the lens for me, while I have hands free for the drill press operation.  So we shall see that, after this is all done, I will have become an "old hand" at lens repair.   

[richardHaw]

Screw extractor saved the day!!!
One of the screws was badly stripped by whoever worked on this thing