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@The Zigmeister is that because of a longer mainspring or something? Because it just doesn't make sense in my head that it can tick more times but last longer than other movements...

@Ubi so you will now have 2 black dial Daytonas? You know... if you want someone to safeguard one for you I would be happy to... you know in case some disaster strikes your house one will still be safe elsewehere :)

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@Ziggy is that because of a longer mainspring or something? Because it just doesn't make sense in my head that it can tick more times but last longer than other movements...

The mainspring barrel is no larger than similar ones, and the spring can only be so thin and you can only get so much of it wound up in the barrel...

Since I did not take the old spring out (not willing to as the barrel is sealed and marked "DO NOT OPEN") I can't say if it's longer or not. I suspect that it's no longer than say the mainspring on a 2836 or on a 7750...

I think the answer lies in the gearing...

A normal escape wheel has 15 teeth, 2 swings are required on the balance to release one tooth. This escape wheel has 21 teeth, so at 10 beats per seconds, and two swings per tooth, 5 teeth are released on the escape wheel each second, and a full rotation takes 4.2 seconds to complete.

On a 2836, with a 15 tooth escape at 8 beats per second, we release 4 teeth every second, and the escape does a full rotation each 3.75 seconds.

I am not 100% sure on the above analysis, as I dont' have my watchmaking books in front of me, but short of counting the teeth in the gears, I think that the answer is the number of teeth in the escape wheel and the rest of the gear train. The 21 teeth are there for a reason, probably to allow a longer running time.

Same calculation with a 10 beat per second on a 15 teeth escape, and the numbers go to: 3 seconds per rotation of the escape wheel...that may be the answer...or I could be way off...

RG

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I've always loved the El Primero movement, and now others in here will know to admire it, thanks to another immortalisation by the Zigmeister.

Any watch with an El Primero is a thing of beauty. I've said it before and I'll say it again...

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Beautiful work as usual Z.

I know El Primero probably the most respected mass produced chronograph movement, but what, in your opinion, are the things that clearly put it above to say, ETA 7750?

Is it the ultra-high beat combined with long power reserve, quality of parts... or robust overall construction? Of course it's probably all these things combined, but what is truely exceptional?

I think the new Rolex 4130 has lower beat rate (28.800 bph) and some people say that it was a "downgrade" when they moved to the inhouse movement in Daytonas. What's your opinion about that?

PS: Randy has some really exceptional frankens. These Daytonas are forger's art... and in many ways much more fascinating than the genuines.

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Thanks for taking the time and effort to post this Rob, I have lost count of the number of times I have gone back to look at your tear down threads.

As has been said before the El Primero is a stunning movement and congrats to you Randy on your second Daytona!

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Beautiful work as usual Z.

I know El Primero probably the most respected mass produced chronograph movement, but what, in your opinion, are the things that clearly put it above to say, ETA 7750?

Is it the ultra-high beat combined with long power reserve, quality of parts... or robust overall construction? Of course it's probably all these things combined, but what is truely exceptional?

The attention to detail, and the quality of the parts, and the engineering that went into reducing stress and friction to the absolute minimum, that is what sets this movement apart from any others I have worked on…

The quality of the parts is exceptional, as good or better than any Rolex. The design is amazing. Why I say this is because this is a 25+ year old movement. Did you notice the lack of something in all the pictures??? There is no brassing anywhere, brassing is when the plated metal wears off, and you can see the “Brass” underneath it. This happens as a result of parts wearing on others or scraping on others. I have never seen any Rolex, that does not have brassing due to the rotor turning, or brassing under the mainspring gear, etc…so that is one point that really stands out.

They also went to extreme lengths to reduce the friction to a minimum, even the 30 minute click is an actual arm, pivoted on jewels, and has a very fine spring to hold it against the 30 minute wheel, same for the 30 minute transfer gear, it’s pivoted on jewels. On most movements these clicks are simple springs pressing against the gears. Putting jewels on rotating parts is standard, putting jewels on levers or arms that only move a fraction of a mm is unheard of in my experience.

A 7750 is a rugged mass produced movement designed to do what it does with the minimal of engineering, and using the cheapest parts and components available. This El Primero is a Formula 1 car by comparison, the best possible parts and components designed to be efficient and have the least amount of friction. If a 7750 sells for $300, then this model, should cost at least $2000 if you considered the design and engineering alone…

I think the new Rolex 4130 has lower beat rate (28.800 bph) and some people say that it was a "downgrade" when they moved to the inhouse movement in Daytonas. What's your opinion about that?

Never seen the 4130 and probably never will…I am sure it’s a well made movement, but I doubt that it would have anywhere near the attention to detail or design of the El Primero…maybe Randy will buy one for me to teardown…

Thanks for the questions.

RG

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:) Well.... Perhaps a 4130 based Daytona is in the forecast somewhere... I need to round out my Daytona collection, and I am not sure that the mod 7750 seconds @ 6:00 116520 is for me.

Speaking of the 4130... I can only comment on this caliber from what I've read; apparently, it's easier to service than the Zenith, as it's organized better- The winding functions and chronograph functions are all self contained under their own respective bridge, and the balance is also now under a bridge (one of the features that I've always liked about the Rolex 3135). The stopwatch function is also more precise as it uses a vertical friction clutch, so that eliminates the little hop that one typically sees when starting the stopwatch. There are numerous other improvements, but it seems that Rolex has really studied the EP400 during it's tenure in the 16520, and have come up with a very nice design of their own.

Still... I myself prefer the El Primero as it is a proven workhorse, well constructed and thought out (as proven here on this review) and to me has better aesthetics in subdial layout. Of course, I also love the 36.000bph beat; something that one wouldn't get in the reworked Rolex 4030 El Primero...

Thanks, by the way, for the very kind comments, everyone :) Much appreciated, as always!

Regards,

R

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Fantastic post, photos and comments, Rob! I've always had an appreciation for the El Primero but this post has me looking under the couch cushions and start saving my pennies. :) Many thanks for taking the time and posting all this information. Awesome!!

Congrats Randy on an fantastic movement and properly serviced at that. I'm with you....who else would you trust with this beauty or any other quality movement for that matter. I've suspected the the Rolex caliber was not on par with the El Primero and I think this post removes much doubt of that.

Cheers,

Jet

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