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Need Help Buying A Speedmaster
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Archer
··Omega Qualified WatchmakerThe 7750 is a much undervalued movement in my mind. I service a lot of these (in various brands, and with various complications) and it is generally speaking the most overall accurate movement I service. It's rare that these do not run very well. Here is but one example, and the last one that I serviced - it's in this Longines Master Moonphase Chronograph, and it's a 7751 variant:
Nicely decorated, but this is not a chronometer rated watch, so keep that in mind:
On the timing machine, checked at full wind over 6 positions:
Here is a shot of the screen - note the red arrow, which indicates the "Delta". This is the difference between the fastest and slowest position, and this is the thing that we watchmakers strive to get as low as possible. Here it's 2.6 seconds over 6 positions:
[URL=http://s248.photobucket.com/user/ArcherWatches/media/Watchmaking2/LonginesMasterMoonphase_0114copy_zps06d61772.jpg.html]
[/URL]
Now to put that into some perspective, Omega allows up to 12 seconds of Delta at full wind, measured over 5 positions for most of their chronometer grade watches. The Regular Cal. 1861 Speedmaster is allowed up to 15 seconds measured only over 3 positions, since it's a non-chronometer watch.
Now they don't all run this good, but I have had a number down below 3 seconds, and anything over 5 or 6 seconds Delta on these is a bit unusual. Now I'll take some credit for adjusting these well, but the fact is I really don't have to do anything exceptional to get very good timing results on the 7750's, where with other watches to get this I would have to go into more time consuming adjustments like dynamic poising. With the 7750 it's usually just a matter of adjusting the balance spring to be flat and level, making sure the spring is concentric, and then adjusting the spacing of the regulating pins with the Etachron tool - takes maybe 5 minutes total in most cases.
These are very solid, reliable, and accurate movements if well cared for.
Cheers, Al
Nicely decorated, but this is not a chronometer rated watch, so keep that in mind:
On the timing machine, checked at full wind over 6 positions:
Here is a shot of the screen - note the red arrow, which indicates the "Delta". This is the difference between the fastest and slowest position, and this is the thing that we watchmakers strive to get as low as possible. Here it's 2.6 seconds over 6 positions:
[URL=http://s248.photobucket.com/user/ArcherWatches/media/Watchmaking2/LonginesMasterMoonphase_0114copy_zps06d61772.jpg.html]
[/URL]Now to put that into some perspective, Omega allows up to 12 seconds of Delta at full wind, measured over 5 positions for most of their chronometer grade watches. The Regular Cal. 1861 Speedmaster is allowed up to 15 seconds measured only over 3 positions, since it's a non-chronometer watch.
Now they don't all run this good, but I have had a number down below 3 seconds, and anything over 5 or 6 seconds Delta on these is a bit unusual. Now I'll take some credit for adjusting these well, but the fact is I really don't have to do anything exceptional to get very good timing results on the 7750's, where with other watches to get this I would have to go into more time consuming adjustments like dynamic poising. With the 7750 it's usually just a matter of adjusting the balance spring to be flat and level, making sure the spring is concentric, and then adjusting the spacing of the regulating pins with the Etachron tool - takes maybe 5 minutes total in most cases.
These are very solid, reliable, and accurate movements if well cared for.
Cheers, Al
