# Zenith Defy Classic Skeleton: Some Technical Info



## Covenant (Apr 22, 2009)

In my recent research into the Defy Classic Skeleton, I found the Zenith product pages lacking in some technical details that I, as a deeply nerdy WIS, wanted to know. So I reached out to Zenith directly and was able to get some answers, as below.

Q1. What grade of titanium is the Zenith Defy Classic made of?

This is important because there's a vast difference between "commercially pure" titanium like the often-used Grade 2, and alloyed titanium. In particular the alloyed Grade 5 is ideal for watchmaking, being stronger, lighter, harder and more corrosion resistant than the defacto-standard 316L steel. You see a lot of debate on Steel Vs Titanium in watchmaking, and a lot of it is misinformed due to the often non-disclosed nature of which _types_ of steel or titanium are being used.

If you'll allow me to geek out about this for a moment, lets get into the nitty-gritty of it:
Stainless steel (316L) offers a tensile strength of 485 MPa, a hardness of 95 on the Rockwell B scale, and generally excellent corrosion resistance. However, this alloy is subject to pitting and crevice corrosion in warm chloride environments. In many marine environments 316 does exhibit surface corrosion, usually visible as brown staining. This is particularly associated with crevices and rough surface finish.

Grade 2 (commercially pure) Titanium is generally less desirable than 316L for watchmaking, offering a tensile strength of 344 MPa and a hardness of 80 on the Rockwell B scale. However the oxide film formed on titanium is more protective than that on stainless steel, and it often performs well in media that cause pitting and crevice corrosion in the latter (e.g., seawater, wet chlorine, organic chlorides).

Grade 5 (Ti-6Al-4V, or an alloy of 90% titanium, 6% aluminium and 4% vanadium) is the best of the lot for watchmaking, with a tensile strength of 1170MPa and a hardness of 112 on the Rockwell B scale (converted from Vickers 396), while offering identical corrosion resistance to pure titanium.

A1. The Defy Classic Skeleton is made of Grade 5 Titanium

Great news on this front, and an excellent choice for a modern sports watch. Grade 5 should be more scratch-resistant than 316L steel, whilst also being lighter, "warmer" in feel (due to lower thermal conductivity) and immune to long-term crevice corrosion from swimming in chlorine or salt water.

Q2. Are half-links available for the bracelet, as the butterfly clasp seems to lack a micro-adjust feature?

A2. Links are very small and is equivalent to around about a half link in other brands.

So no real half-links or micro-adjust, which may be problematic for those who need to achieve a perfect fit, however the comment about the links being smaller than normal anyway is somewhat reassuring.

Q3. Your website notes that the escape wheel and lever are made of silicon, but does not specify the material used for the hairspring. Can I inquire what this is made of?

A3. Hairspring is Nivarox, with their own proprietary alloy.

Nivarox hairsprings are alloys of 45% cobalt, 20% nickel, 20% chromium, 5% iron and smaller percentages of titanium and beryllium. The alloy is not immune to magnetism (being made largely of ferromagnetic metals), but the high percentage of chromium does dampen its response to magnetism.

Q4. Following on from the previous question, does Zenith provide a Gauss rating for how magnetically-resistant this timepiece is, given the use of silicon in the escapement? 
A5. As you are no doubt aware the whole movement needs to be protected in order to be anti-magnetic, either by a faraday cage or similar.

Something of an evasion of my question, but I understand the brand's reluctance to warrant any skeletonised timepiece as anti-magnetic. Given a Nivarox hairspring with a silicon escapement, I wouldn't be surprised if the Elite 670 SK is more resistant to magnetism than the 4,800 A/m that ISO 764 requires.

Q5. Do Zenith provide any guarantees of the daily timekeeping accuracy for this watch? 
A5. There is no guarantees on accuracy as this is dependent on the wearer's habits, surroundings, environment, care, etc. However, the watches all leave the Manufacture at an accuracy well within the COSC tolerance.

Interesting that Zenith watches are being tested to within-COSC specifications for timekeeping before leaving the factory. Some digging into the user manual for this watch also revealed the following:

_Accuracy_
_Under normal conditions of use, the precision discrepancy_
_for our automatic watches is a maximum of 4 to 5 minutes_
_per month in comparison to the standards on the market.

_So a maximum deviation of 10 seconds per day. While this sounds poor in comparison to say Rolex or Omega's warranties, it's pretty standard for a non-COSC certified modern timepiece. The Grand Seiko 9S movement is also warranted to +10 spd during regular use, for instance.

Q6. How long is the warranty period on this watch? 
A6. Warranty is 2+1- additional 1 year warranty when you register your watch.

Again not great compared to Rolex and Omega (5yrs) or JLC (8 years), but better than the standard 2 years for most brands at least.

Q7. Are adjustments and regulations of timekeeping covered under warranty? 
A7. Yes

So at least if you start getting deviations greater than 10 spd Zenith will regulate your watch for free while under warranty.

Hope that's of some use to anyone considering a Defy Classic Skeleton, like I am. I just now need to decide whether I can accept accuracy in the 10spd range (even though I'm sure that anecdotally most Elite 670 SK's will perform better), and whether I can deal with no warranted magnetic resistance. I ended up trading away a Nomos Neomatik because I kept getting it magnetized, but that's a very slender watch with no silicon components in the escapement at all. I wonder just how much better the Zenith would fare in this regard.

Oh and if anyone's interested in substantiating any of the above, here are my sources:
http://www.atlassteels.com.au/documents/Atlas_Grade_datasheet_316_rev_Jan_2011.pdf
ASM Material Data Sheet
ASM Material Data Sheet
https://www.ingentaconnect.com/content/sut/unwt/1996/00000021/00000004/art00005?crawler=true
https://www.steelexpress.co.uk/steel-hardness-conversion.html
https://www.zenith-watches.com/medi...oi/ZENITH_MDE_EN/zenith_mode-emploi_elite.pdf
https://www.grand-seiko.com/au-en/about/movement/mechanical/9s65
https://www.rolexforums.com/showthread.php?t=130539

Regards,
Jason


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## Hartmut Richter (Feb 13, 2006)

Thanks for the great write up! On the question of magnetism, Omega have recently introduced a watch that is almost entirely immune to it - without any protective cage! It's all down to making the vital parts (entire escapement, incl. balance and hairspring) completely resistant to this factor.

Hartmut Richter


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## natesen (Mar 6, 2012)

Thanks for sharing the technical info! 

Sent from my LM-G710 using Tapatalk


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## kennkez (Jun 5, 2018)

Thanks for sharing, especially the additional 1 year warranty


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## Drksaint (Dec 30, 2012)

Thank you for taking the time to write this up. I love this watch. My next purchase for sure.


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## watches.ist (Sep 5, 2012)

Because no thread is complete without pictures:


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## jjspyder (May 1, 2018)

Hartmut Richter said:


> Thanks for the great write up! On the question of magnetism, Omega have recently introduced a watch that is almost entirely immune to it - without any protective cage! It's all down to making the vital parts (entire escapement, incl. balance and hairspring) completely resistant to this factor.
> 
> Hartmut Richter


Tag Heuer also has a new carbon based hairspring and an escapement completely immune to magnetism called the Isograph. This movement is found in the new Tag Heuer Autavia line. Since Zenith and Tag Heuer are both LVMH brands, I wonder if this will find its way over to Zenith.


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## Contaygious (May 9, 2014)

Companies need to put this info on the website. So rediculous it isn't there when spending so much money.

Also sad about the guas and 10s a day...Omega way less and more precise.


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## palletwheel (May 15, 2019)

Hi Covenant - would you happen to have similar specs for a closed Chronomaster El Primero? I would especially love to know about accuracy and magnetism on this piece. Appreciated if you do, thanks!


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## issey.miyake (Mar 8, 2011)

Nice write up - thanks for the effort in putting that together. 

I’m considering this watch (well more the closed version) but the skeleton is definitely growing more and more. Can not afford the AP version so this will be it to cover that segment lol.


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## Gregory117 (Dec 6, 2018)

Thanks for posting---this answers a lot of questions.


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## HDK (Apr 29, 2017)

thank you for the great info!


Sent from my iPhone using Tapatalk


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## aball (Jul 18, 2012)

It's a shame that detailed information about anything seems to be gradually disappearing. I read old vacuum tube stereo manuals and they were super technical despite the fact they were aimed at the general population. Not so today - they apparently assume everyone is mostly ignorant, which unfortunately might not be too far off.

As for the accuracy, when writing any datasheet we always do our best to publish and state worst-case values. This does not mean that the performance of the part will be anywhere near those values 95% of the time. It's a statistical factor in the exponential failure distribution, once you are in the central portion of the "bathtub" Weibull distribution. The 5 min/month is, therefore, the threshold where they consider the watch to be "out-of-spec" and needing service. In this regard, they are right on the money, and I commend them for actually giving out a number.

My Zeniths are very accurate. If it weren't for my GMT-IIC, they would handily be my most accurate watches, and have the most dependable power reserve of all of them (though my IWC is very close).


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## fskywalker (Jul 14, 2014)

Congrats!


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## jupera2005 (Jul 15, 2011)

palletwheel said:


> Hi Covenant - would you happen to have similar specs for a closed Chronomaster El Primero? I would especially love to know about accuracy and magnetism on this piece. Appreciated if you do, thanks!


Hi,
My chronomaster 1969 is performing +4 spd. I've got it for few months. Don't know about magnetism.








Enviado desde mi H3113 mediante Tapatalk


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## kritameth (Oct 11, 2015)

Thank you for the great write-up, Jason! This shall accompany me on my journey down the Zenith rabbit hole.


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## mokujin (Aug 12, 2013)

I've seen two versions of this watch (in regards to the movement's escape wheel), but haven't been able to find anything mentioning the disparity. There's the pic posted earlier in this thread (which is the more common version I've seen), and then there's this version, in which the escape wheel is less visible:


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## kritameth (Oct 11, 2015)

mokujin said:


> I've seen two versions of this watch (in regards to the movement's escape wheel), but haven't been able to find anything mentioning the disparity. There's the pic posted earlier in this thread (which is the more common version I've seen), and then there's this version, in which the escape wheel is less visible:
> View attachment 15357845


I see it, that's interesting...


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## WTSP (May 6, 2012)

If imitation is the most sincere form of flattery, Edox is being very flattering of Zenith.


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## Hartmut Richter (Feb 13, 2006)

OUCH! And the case is probably flattering Hublot.....

Hartmut Richter


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## WTSP (May 6, 2012)

Edox, seriously? People have complained about Zenith borrowing from Rolex. I suspect that this Edox won't garner enough attention to really be discussed though.


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## cmak (Feb 4, 2012)

This watch is something else. Been drooling over this on chrono24 lol


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