# ETA 2824-2 vs Miyota 8215



## Scott3670 (Mar 16, 2006)

Hello,

I'm new to this forum and have a few basic questions. Can anyone give me some basic info on the difference between these two movements? Is one that much better than the other? What about overall durability (I'm hard on watches)? Also what is the difference between 28,800bps vs 21,600bps?

Sorry for the newbie questions but I'm eager to learn - and this is the best place to do so!


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## bmwfreak (Jun 7, 2008)

Good question. I'll answer to the best of my ability regarding basic features. I'm not a watchmaker.

1. Big cost difference. ETA more expensive.
2. 28.8k vs. 21.6k. ETA will have a "smoother" sweep second hand
3. ETA will hack (second hand stops when setting time). Miyota does not hack.
4. ETA can be manually wound. Not sure if Miyota can be manually wound with crown.
5. Hand sizes are different. More hand options for ETA if building your own watch
6. Dial feet location. dials are not interchangeable between the two unless modified

The miyota is a fine movement for the money. I guess it depends if you are shopping for a watch or shopping for a movement to build your own watch. If building your own, you'll have more dial and hand options with the ETA. I've owned serveral watches with ETA 2824-2 and a few Invictas with Miyotas. The Miyota is a good reliable movement for the money. The ETA runs 2-3x the price. There are also different levels of the ETA. Some have been adjusted to different positions by ETA, some are "unadjusted". Of course the higher levels cost even more $.


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## lysanderxiii (Oct 4, 2006)

You can hand wind a Miyota.


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## flame2000 (Jun 27, 2007)

Here is an interesting article about the Miyota 8215 and ETA 2824-2.....

http://www.17jewel.com/two.html


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## Scott3670 (Mar 16, 2006)

Wow, great information! Thanks to everyone for their help.


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## lysanderxiii (Oct 4, 2006)

> *BPH* - Beats per hour. ETA 2824-2 28,800 BPH or 8 beats per second (4 Hz) vs 21,600 or 6 beats per second (3 Hz) for the Miyota 8215. Most mechanical movements run at 18,000 BPH or 5 beats per second (2.5 Hz). Both movements have higher than average BPH a plus.


This was true in the mid sixties, these days there is probably an even split between 21,600 and 28,800, even in really expensive movements. 


> *Jewels* - The ETA has 25 Jewels and the Miyota has 21 Jewels. Jewels, typically synthetic rubis are used in watch movements, not to add to their value, but to reduce friction and wear on moving parts. Lower end watches may have only 7 to 15 jewels. The standard for quality watches is 17 jewels or more. There is an upper end to the number of jewels necessary, typically, anything over 25 jewels for these types of automatic movements are just for decoration.


Nobody these days makes mechanical watches with less than 17 jewels.

The ETA has 16 "useful" jewels that actually reduce friction in the timekeeping parts of the movement. The remaining nine only help the autowinding mechanism, and some of their utility is questionable.

-The bottom of the barrel arbor is jeweled, but not the top?

-On the 25 jewel ETAs only one of the reverser wheels has jewels pivots for the pawls, and then only the top (visible) part of the axle is jeweled, but the 21 jewel ETAs have both reverser wheel pawls jeweled (but, again only the visible part of the axle). Why?

The reason is to fully jewel all pivots would generate a non-standard 32 or 33 jewels* (The usual jewels numbers are 17, 21 and 25), so the not so important ones can be added or subtracted to get a "standard" jewel count.

(As an aside, the autowinding mechanism in most ETAs has four gears, ywo of which are reverser gears with two pawls each, giving a total of eight axises, which, if each axis is given two jewel bearings, could total 16 additional jewels.)

The Miyota actually uses 17 "useful" jewels in the timekeeping part of the watch, but that is only because the Miyota has a separate pinion for the second hand (being indirectly driven). and the additional 4 jewels in the automatic winding mechanism are pivots for the two wheels in the mechanism. Fewer wheels as it only winds in one direction.

In short, as far as I am concerned, a quality movement these days should have at least 17 jewels, if it has more, that could be better, but it really doesn't matter how many more; 21 or 35 jewel movements have so little difference in efficiency the extra number of jewels don't matter.

__________________
* one pivot in the automatic winding sytem is a gear on a post, to jewel it, the post can be a jewel, or the hole in the gear can be a jewel, or you could jewel both, hence 32 or 33 jewels.


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## Scott3670 (Mar 16, 2006)

Well I sure asked the right people for this information. I have two watches (Marathon and Halios), with obviously different movements. I guess my question should have been more about whether the Miyota is as good as the ETA. It seems that after reading all the information here that any concerns I had about the qualityof the Miyota movement are null and void.

Thanks again to everyone for giving me such a good education.


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## n1ugn (Sep 29, 2014)

Bottom line is the miyota "hammer"winds in only one direction,Seiko while still 21,600,winds in both directions (orient too)most Swiss are 28,800(but I have a Tissot powermatic 80...80 hour reserve that is only 21,600 in part to achieve the 80 hours)but all Swiss winds in both directions,hacks,hand
Winds. John D


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## Joe Horner (Nov 11, 2011)

It's worth noting that Miyota using single direction winding was an intentional design decision made, not for cost or simplicity, but because they determined that it's actually more efficient when the watch only experiences small movements (such as sitting at a desk all day). The extra friction and "lost" movement of the auto weight inherent in most bi-directional systems can prevent winding under those circumstances.


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## calebk (Feb 4, 2015)

It might also interest you to note that Miyota has a higher end 9015 movement, that, in many ways, has been compared to the ETA 2824-2 because it runs at the same high beat of 28,800bph, has hand-winding and hacking too.


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## pithy (Aug 22, 2010)

calebk said:


> It might also interest you to note that Miyota has a higher end 9015 movement, . . . . . . . .


Naaaaaah.


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## Samantha (May 14, 2010)

Hi calebk,
Just an observation, this post you're replying to is almost 6 years old.
Samantha


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## Joe Horner (Nov 11, 2011)

My fault, Samantha. I replied to N1ugn without realising he'd made a zombie thread.

On the other hand, at least I'm only 3 days late with this post


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