Richard sent in his Speedmaster Professional for a service. It has the 1861 movement, which, compared to the 861 (and the 321) has a rhodium plated movement, and I like the finish.
The case back makes the link back to the original Moonwatch, which has the calibre 321 movement. The 1861 has some minor modifications compared to the 321, but it is indeed almost the same movement. 
First peek at the movement. Very nice finishes throughout, and the movement is in pristine condition. No scratches, all screw heads undamaged, and I intend to leave it that way 😉
The bottom plate with the hour recorder.
I start taking apart the chronograph.
The wheel train.
Time to take apart the bottom plate.
Time for the cleaning machine.
As usual, I start off with a new mainspring.
In order to put the base movement together, I put the hour recorder bridge on the bottom plate. You can also see that I have already put in the balance jewels.
The base movement is back together, and ticking.
I adjust the movement, and I’m very happy with what I see.
Now that I know the base movement is performing as it should, I can put the chronograph back together.
The top plate is back together, and looking beautiful. It is indeed possible to take apart a movement, and put it back together without leaving any marks or scratches.
Ready for the dial and hands.
Cased and waterproof tested.
I have a Cal 861 Speedy from 1971 and another 861 in a 1997 De Ville Prestige, but I do like the look of the rhodium plating in the 1861. I’ve never been able to find any details of benefits this might confer over older versions. Was this just a marketing move or does rhodium offer real advantages?
I can only speak from dealing with the plating, and the rhodium plating appears to last better than the standard copper and other bits plating that Omega used to have.
。残念私の英語は全くの最善ではありません。それはスペイン語にこれを発送へ批判に耐えている場合、あなたが精通している行います。それは非常に親切であろう。
This moon watch is a perfect match for me an aerospace machinist .i was born on the same date as niel armstrong
Thanks Christian, very interesting to see the inside of my own watch! I am pleased and slightly surprised to see that it was so clean inside – I had expected at least a little grime or dried out grease and dust as it has been on my wrist every day for the last 8 years.
Love a speedie, and the movement is pretty swanky in rhodium.
I do like the serial number being the same on the case as the movement, but I associate that with chronometer rated watches – and this doesn’t say anywhere that it is..?
No Speedmasters with cal 1861 (nor 321/861) have been chronometer certified. Omega created some limited series calibers 864 and 867 that is modified 861 movements which meet COSC certification.
Seems strange that Omega wouldn’t COSC certify them, but maybe they consider the Certified for Manned Space Missions bit to be the higher standard!
I think the movements are constructed with emphasis on robustness and not necessarily ultimate precision.
COSC are precision oriented, NASA had focus on survival!
Let’s also not forget that these watches aren’t used for timekeeping on board.They are just for the individual astronaut, and I’m sure they are set daily.