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Discussion Starter #1
Over the last couple of months i have been asked about Allen/Hex key sizes.

So just a little information about sizes.

  • 1.5mm = 0.0591"(imperial)
  • 1.6mm = 0.0630"(imperial).
  • 1/16" = 0.0625(imperial).

So basically a 1.6mm key is within 0.0005" (five tenths/half a thou) of a 1/16" so for all intents and purposes 1.6mm is near enough the same as 1/16" imo, this information will/could save you hunting every were for a 1.6mm key :)



 

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Very useful info for the engineering challenged, John. Here's a pdf version of a book I've had for donkey's years -the Presto tools counsellor (2013 copy)
 

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If you need exactly 1.6mm try here.

Technasales Ltd
34-36, Peabody Rd, Farnborough, Hampshire, GU14 6EY
Tel: 01252 547709

They do hex keys in 0.1mm increments in various sizes.
I.E in the 1mm range they do 1.2, 1.3, 1.4, 1.5, 1.6, and 1.7.
 

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Hi!

Recently I sent a few 1000 tunas for batt replacement. Three tunas that use allen/hex screws.

I'll pass along the experience I ran into with them...

My watchmaker had some tuff times to extract the screws without damage. In fact he wasn't able to. :(
After learning from the mistake of using an allen wrench of the flat head type, I got a solid advice from my friend Shannon Spence about tuna allen screws and the correct key type. In fact, Shannon's advice is worth its weight in gold! :cool:

Shannon tipped me off about the Bondhus allen screwdriver. Bondhus is the company that actually created the allen/hex screw, to begin with. So they know a thing or two about how to extract them without leaving any marks, no matter how tight they are (and the [email protected]$&*ers at Seiko know how to attach them tight! :mad::mad::mad:).

The Bondhus screwdriver has a ball, espheric head, so when one inserts it into the screw, the Bondhus tool gets snugly, juxtaposed fit inside the screw, so it allows for a great force transference into the screw upon extracting motion, without any spaces or play inside of it. And the fact that it has a ball end/head allows for a proper fitting inside the screw, thus preventing striping or marking the screw head.

The allen screws size used in the tunas (both SBBN015, SBBN017, SBBN011 and SBBN013, and also SBDX011) is exactly 1.5mm. A 1/16'' screwdriver won't fit inside the screw. Ask me how I know! ;)

I've bought both sizes of the Bondhus screwdriver: 1.5mm and 1/16''. Only the 1.5mm fit inside the screw, but it was a 100% match, perfect fit of the exact type. The 1/16'' screwdriver didn't allow to reach full inside the screw head, where the ball end should sit snugly to allow proper torque motion in a way not to damage the screw.

The best part: you can buy a pair of Bondhus ball screwdrivers of 1.5mm on ebay, from a seller called omnitools (they sell stuff for aeromodelism), for around $4 usd a pair!

Not affiliated with the seller. Just spreading the news.

I can't thank my buddy Shannon enough for such golden tip as this. :D
 

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Just a note regards the ball ends. These are designed to allow faster removal of the screw/bolt and slight angular misalignment between the allen key and bolt axis is permitted (due to the ball). However, for high torque applications (ie when the screw is tight) the balls are not recommended. This is because the contact points of the ball in the screw socket is obviously smaller that a non ball end - where flats contact against flat surface.

If you look, you will see that the balls are only on the long sides of the allen keys. This is deliberate. If the long side is in the socket, then it leaves the short side out for leverage. And short side gives lower leverage that the long.

As Archimedes once said - give me a lever long enough and i will move the World. The converse is also true
 

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Discussion Starter #6
Just a note regards the ball ends. These are designed to allow faster removal of the screw/bolt and slight angular misalignment between the allen key and bolt axis is permitted (due to the ball). However, for high torque applications (ie when the screw is tight) the balls are not recommended. This is because the contact points of the ball in the screw socket is obviously smaller that a non ball end - where flats contact against flat surface.

If you look, you will see that the balls are only on the long sides of the allen keys. This is deliberate. If the long side is in the socket, then it leaves the short side out for leverage. And short side gives lower leverage that the long.

As Archimedes once said - give me a lever long enough and i will move the World. The converse is also true
I agree with Barry, the ball end is really for use when you can't get the correct alignment to the head of the screw/caphead and for this application the ball end is perfect but when you can align correctly you would use the hex end as there would be more of the faces in contact.
 

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Two points to consider:

1) The Bondhus ball end allen screw-driver it's not an L-shaped tool. It is exactly like a regular screwdriver, with a handle to grip, thus making it easier to apply torque and not damage the screw by sliping the tool.

2) At first, my professional watchmaker (none other than an authorized facility for the Swatch Group brands, Audemars Piguet, Hublot and the likes, so they have experience with pretty much every type of watch and screw that is outhere) used just a regular 1.5mm L-shaped allen tool (flat head) to remove the screws. After a lot of carefull steps, some screws got totally stripped, specially the ones located at the bottom of the shroud, at the crown side (which got me very curious due to such coincidence).
I was forced to source the OEM brand new hex screws (in the package) for replacement, since a few of the original ones once installed in the watches were rendered totally useless.

So after learning my experience the hard way ($$$ !), and trying the Bondhus tool afterwards, I have finally found peace of mind next time those watches need to be opened, so I cannot stress enough to my fellow tuna collectors that own models which employ hex screws to invest a few dollars in a Bondhus 1.5mm ballhead driver.

Here is the Bondhus tool:

 

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https://www.youtube.com/watch?feature=player_embedded&v=1Qu9fsNnbNs
They certainly do take their tools seriously, and a few dollars more, saves dollars in new screws.
I'd take Chris's recommendation, but if you cant get them , then stick to good quality -like Wiha, Wira etc.
Ultimately - don't use tools that are cheap and nasty and make sure they FIT properly!!!
 

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How could a screw that small need that much force applying to it? Just my tuppence worth, but if they were that much of a problem for a watch maker, either tool would of fallen short, a vice like grip and forearms like Garth would of been needed to use that screwdriver type, and too much torque applied using an L shaped Allen key. I've used both types, in engineering, 0.5mm upwards, and experienced these problems. Not that any of this helps now, bit I'm still baffled.
Regards, David
 

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I've removed a few of these on various Tunas and Sawtooths and I've stripped a few heads doing so. I used 1.5mm allen keys too. The thing I've come to find is that not all 1.5mm allen keys are alike. As with anything manufactured, they are built to different tollerances and some fit snugger than others.
Do yourself a favour and buy only high quality tools. Don't use the one that came with your IKEA furniture. This will help alleviate the problem considerably. And if you buy a 1.5mm Allen key and it doesn't fit snuggly, DON'T USE IT. You will strip the head. Find one that fits snuggly.
 

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I've removed a few of these on various Tunas and Sawtooths and I've stripped a few heads doing so. I used 1.5mm allen keys too. The thing I've come to find is that not all 1.5mm allen keys are alike. As with anything manufactured, they are built to different tollerances and some fit snugger than others.
Do yourself a favour and buy only high quality tools. Don't use the one that came with your IKEA furniture. This will help alleviate the problem considerably. And if you buy a 1.5mm Allen key and it doesn't fit snuggly, DON'T USE IT. You will strip the head. Find one that fits snuggly.
One of the best piece of advices ever given here. I can stress enough how much I agree with you on every word, brother. :cool:

I'm a firm believer that Seiko applies thread locker to those fuckers, upon fastening them in the factory. Upon removal, all of my screws came out with a whitey goo, totally dry, on the thread portion.

I can't understand the real need to apply thread locker on a screw located in a part that won't see any play, movement or vibration. It only makes our life a living hell. :mad:

And it is not so much the need of applying force on the screws to back them out...the difficult part here is how to extract them without causing damage to them, cosmetically and also functionally. :(

The Bondhus has its weight worth in gold. Mark my words.
 

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I imagine that thread locker/sealant is used to reduce salt water ingress and also prevent dissimilar metal corrosion.
I would think the screws are machine fitted - so maybe the answer is to use a cordless impact driver, not the wheel/lugnut size ones, but the cordless screwdriver type which use screwdriver bits.
Many times I've tried to undo fasteners that won't budge with a bar, but they'll shock off within seconds.
 

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don't want to sound negative, but...

original Tunas have " + " screw heads. Anything after that is just a fake :)

about the glue inside, I bet this is typical Japanese stuff: "we at Seiko make the watches, we screw the shrouds on tighter than anybody else can AND we can unscrew and screw them back in place as we please"... and all other people messing with our watches should pay the price.
I LOVE the Japanese --or rather I should say I have unlimited respect for their achievements in engineering, traditional arts and crafts, etc. but they tend to be pretty arrogant about those very qualities, and certainly have no great love for foreigners ("gaijin" and among them more specifically those hailing from the USofA?) so I wouldn't be at all surprised that they glue the #$%&ers in so tight just to make you guys' life difficult :p:p
 

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original Tunas have " + " screw heads. Anything after that is just a fake :)

about the glue inside, I bet this is typical Japanese stuff: "we at Seiko make the watches, we screw the shrouds on tighter than anybody else can AND we can unscrew and screw them back in place as we please"... and all other people messing with our watches should pay the price.
I LOVE the Japanese --or rather I should say I have unlimited respect for their achievements in engineering, traditional arts and crafts, etc. but they tend to be pretty arrogant about those very qualities, and certainly have no great love for foreigners ("gaijin" and among them more specifically those hailing from the USofA?) so I wouldn't be at all surprised that they glue the #$%&ers in so tight just to make you guys' life difficult :p:p
Only if you clarify "original" to mean the first tunas - with Ti screws, as the later ones are also totally original and don't have "+" heads or Ti screws.
These watches were originally designed to be serviced by Seiko factory only, and they managed to work on them successfully- obviously using the correct tools and techniques, so what is the problem??
I don't think your assessment of the Japanese people's lack of love for foreigners or thier arrogance is really appropriate or necessary -whether or not you believe it to be true, this is an international forum and we shouldn't be perpetuating racial stereotyping -especially if you claim to "love" the Japanese.
 

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These watches were originally designed to be serviced by Seiko factory only, and they managed to work on them successfully- obviously using the correct tools and techniques, so what is the problem??
I don't think your assessment of the Japanese people's lack of love for foreigners or thier arrogance is really appropriate or necessary -whether or not you believe it to be true, this is an international forum and we shouldn't be perpetuating racial stereotyping -especially if you claim to "love" the Japanese.
Hear, hear. No watch company is obligated to make their product simple to work on by anyone without proper training and brand-specific information. Thread-adhesives are commonplace in the watch industry because the relative tightening torques that small fasteners can withstand are not always matched by the forces they experience day after day, year after year. Small repetitive movements and vibrations add up!
I'm sure we can all agree that it would be great to see how the factory properly does it!
 

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Here, here. No watch company is obligated to make their product simple to work on by anyone without proper training and brand-specific information. Thread-adhesives are commonplace in the watch industry because the relative tightening torques that small fasteners can withstand are not always matched by the forces they experience day after day, year after year. Small repetitive movements and vibrations add up!
I'm sure we can all agree that it would be great to see how the factory properly does it!
They do it with the correct tool, that's all. Once I was finally able to locate the correct tool, never a problem again to unscrew the screws.

And about a watch company making a product simple to work on, that's how you want a so called "tool watch made for professional use" to be.

Easily serviceable without any secret recipes or complicated diagrams. Otherwise, you will be chained to the Seiko authorized service center (or the factory for that matter, since this JDM watch was meant to go back to the factory once servicing/maintenance is in need) for a simple battery replacement where no other watch part needs replacement besides the battery itself.

C'mon people...we are talking about 4 simple allen screws to be extracted without any kind of damage from the watch! How hard can it be for a maker to assemble a watch that allows a regular professional watchmaker to take it out with his own tools of the correct size?

I also think that the old tunas with the "+" screw were much more damage proof than this prone to stripping allen screw, and then once again it is inevitable to call out on the "tool aspect" of the watch with such a poor choice in a non-functional screw type. I tend to believe that in this instance, Seiko went for the cosmetical aspect first, leaving the practical or functional aspect to second place.

What is the problem with a PVD/DLC phillips screw?

And I maintain my stance about thread lockers on those shroud screws...there's absolutely no need for it, so much so that I forbidded my watchmaker to apply that damn thing to the screws upon reassembling the watches.
 

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Thread-adhesives are commonplace in the watch industry because the relative tightening torques that small fasteners can withstand are not always matched by the forces they experience day after day, year after year. Small repetitive movements and vibrations add up!
Unless you have this guy's job and wears a tuna while at it, then there's no need to use a thread locker to a non-moving part screws, IMHO.

 

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original Tunas have " + " screw heads. Anything after that is just a fake :)

about the glue inside, I bet this is typical Japanese stuff: "we at Seiko make the watches, we screw the shrouds on tighter than anybody else can AND we can unscrew and screw them back in place as we please"... and all other people messing with our watches should pay the price.
I LOVE the Japanese --or rather I should say I have unlimited respect for their achievements in engineering, traditional arts and crafts, etc. but they tend to be pretty arrogant about those very qualities, and certainly have no great love for foreigners ("gaijin" and among them more specifically those hailing from the USofA?) so I wouldn't be at all surprised that they glue the #$%&ers in so tight just to make you guys' life difficult :p:p
Have you been following the developments in the Swiss watch industry lately? I'll leave it at that.
I don't think you know any Japanese people, or if you do you don't know them very well. A lot Japanese are fascinated with French and American culture, especially their idea of the Californian beach lifestyle. (I'm married to one).

Sorry guys. Back to the topic at hand.
 

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relax...

I thought smileys
were used to signal a joke or otherwise deliberate "overstatement", etc.

For those of you who thought my criticism of the "Japanese" (lumping one people in one single lot being wrong in the first place anyway) was "out of order" or downright racist, I will just signal that I am half-Japanese myself, my wife is Japanese, therefore over half of my family and many of my friends are Japanese... and if that were not enough I work daily with Japanese colleagues, in Japanese language, etc.

...but then I am also partly French and therefore feel quite free to criticize the French for their arrogance, stupidity, cultural superiority complex and MANY OTHER QUALITIES --all good fun...

As for the "Americans", the Latin American part of me (the part that spent spent some time living in Buenos Aires) thinks they're all YANQUIS




BACK TO TUNA SHROUD SCREWS: I agree 200% fully with Chris


I also think that the old tunas with the "+" screw were much more damage proof than this prone to stripping allen screw, and then once again it is inevitable to call out on the "tool aspect" of the watch with such a poor choice in a non-functional screw type. I tend to believe that in this instance, Seiko went for the cosmetical aspect first, leaving the practical or functional aspect to second place.
"+" screws protruding out of the classical Tuna shrouds are cool, beautiful, simple, unassuming, practical, resistant... why change to Allen/hex???


With shared love of Seikos, admiration for ALL things Japanese and strong interest for inter-cultural exchanges all in good fun hopefully........Philip
 

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PS> come to think of it...

the fact that my wife of 30+ years is Japanese may be one reason I sometimes feel annoyed with "the Japanese" in general... does that constitute an excuse for the mood expressed in my statements above? :grin:
 
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