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ETA 2824-2 vs. Miyota Cal 821a Movement

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ETA 2824-2 vs. Miyota Cal 821a


The majority of watchmakers don’t have their own in-house movements. They usually purchase their movements from ETA, Citizen and other firms. This became common after the popularity of quartz powered watches in the seventies and eighties when everyone wanted a quartz watch for their unparalleled precision, reliability and affordable pricing, forcing the surviving watchmakers to start buying movements rather than developing their own.

Two of the most popular watch movements found today in several watch brands are the Swiss ETA 2824-2 and the Miyota Cal 821a. Both are excellent movements and provide accurate and reliable mechanics for your popular timepieces. We see the ETA 2824-2 movement in many watch brands such as, a.b.art, Altanus, Cartier, Junkers, LACO, Maurice Lacroix, TAG Heuer, Tissot and Zeppelin. While the Miyota movement is common in lower priced watches (around $500 or less) from Junkers, Invicta, LACO, and many others.

These two movements are very similar, but have some significant differences:

  • Both movements are automatics, using a winding rotor to power the main spring as you move around during the day.

 

  • Power reserve: Automatic movements have a power reserve built in so the watch can keep running while it is not being used. The ETA comes in at a very respectable 40 hours of reserve, but the Miyota trumps it in this category with 45 hours! That being said, the ETA does utilize ball bearings for the rotor, which means it’s more efficient at winding the watch, requiring less wrist time per day to keep it going.
  • Jewels: Both watches utilize synthetic rubies in their movements, the ETA 2824-2 is a 25-jewel movement and the Miyota comes in with 21 jewels.
  • Beat Per Hour (BPH): The ETA 2824-1 performs at 28,800 beats per hour, 8 beats per second or 4Hz. The Miyota 821a will only beat at 21,600BPH, 6 betas per second or 3Hz. This means the ETA movement is smoother and more accurate, because it beats faster. However both watches are above average, traditionally mechanical watches were always 2.5Hz (18,000 BPH)
  • Direct second hand drive vs. Indirect second hand drive: Perhaps this is one of the most significant differences within these two movements.


The ETA 2824-2 movement comes in with factory direct second hand drive meaning that the second hand will not stop for moments at a time due to wrist movements.

 

The Miyota 821a comes with an indirect drive second hand, which causes the second hand to “pause” due to strong wrist movements. The “pause” is caused by the small play within the teeth of the third wheel in the train that turns the second hand, in average the maximum amount of play equates to 2 seconds “pause” but usually the movement will “pause” for less time. This is again an aesthetic issue, since the indirect second hand drive won’t affect the accuracy of the watch.

 

  • Hacking second hand: the ETA 2824-2 is a hacking movement where the second hand stops while the time is being set; on the other hand the Miyota 821a does not
  • Shock resistance: Both watch movements offer excellent shock resistance. The ETA uses Incabloc, which is a method that allows jewels to float when the watch is bumped. The Miyota has a proprietary shock resistance called the Parashock.

 




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