Nivada With As 1950/51 Movement

[clockwatcher]

Hi All!

 

Through the post this morning came my latest acquisition - a Nivada Compensamatic with AS1950/51 movement. It's an attractive watch in lovely cosmetic condition and was, as usual, had for pocket money.

 

It was described as running erratically. After letting down the mainspring, which had been wound tight, I got the balance wheel oscillating with my rubber air puffer and peered into the works. The balance was fine and the hairspring free and undistorted but the balance would only go with air assistance so I decided to remove it and have a closer look.  I removed the balance bridge screw and almost immediately the watch started running but I noticed that, depending on what attitude the watch was held in, the escape wheel was engaging intermittently. At the moment it's sitting on a pad face up and ticking away quite happily but turning it face down and angling it allows the escape wheel to miss the pallet altogether.

 

As a shiny newbie I'm having to guess what might be wrong but could it be that an escape wheel pivot has broken?

[Geo]

I think you are on the money with your diagnosis. Very gently try lifting the the wheel with a dry oiler, you should see it wobble.

[clockwatcher]

Thanks Geo!

It was all I could think of. I presumed that, as it runs, there wouldn't be any problem with the pallet so that was all I was left with. This begs the question 'Where do I get a replacement?' Is this the sort of thing that can be got from Cousins or should I look for another Compensamatic movent?

[clockwatcher]

I felt that I ought to pull my weight so went to Cousins' website and searched for an AS1950 escape wheel. What they list is an AS1940 escape wheel. Looking at Ranfft's pages I see that both these movements are 21600 beat movements and the difference is that one is 10.5"' and the other 11.5"'. http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&AS_1940

 

They seem to be from the same family so could the escape from one do for the other?

[Don]

Jules Borel has a nifty parts search which lists interchanges between different models. Here's the search I did for AS 1951:

 

WATCH MATERIAL INTERCHANGE LIST  705/1234  ESCAPE WHEEL, S/S  705/STA 1950  Price Each  $  26.20    AS 1940  21600 BPH-DSS-SHOCK-ADJ-STUD HOLDER  AS 1941  21600 BPH-DSS-CALENDAR-SHOCK-ADJ STUD  AS 1950  21600 BPH-DSS-SHOCK-ADJ STUD HOLDER  AS 1951  21,600 BPH-DSS-CALENDAR-SHOCK-ADJ STUD HOLDER

 

 

Looks like the AS 1940 escape wheel is common with the 1950/51. If you can't find the individual part cheap enough, an entire movement is the way to go. You can either swap parts or the entire movement. Either way you'll have lots of spare parts should anything fly off your tweezers into the ether.

 

These two are listed as NOS. Might be worth a look:

 

http://www.ebay.com/sch/m.html?_odkw=as+1951&_ssn=vacheron_nl&_armrs=1&_from=R40&_osacat=0&_from=R40&_trksid=p2046732.m570.l1313.TR0.TRC0.H0.Xas+1950.TRS1&_nkw=as+1950&ghostText=&_sacat=0

[clockwatcher]

Thank you Don, that's most useful!

 

Cousins list the AS1940 escape @ £8.52 (about $13) so I might go with that, as the movement I have is pristine apart from the EW.  The complete movement would certainly slot straight in but where's the fun in that? :biggrin:

[Don]

You're welcome. With the escape wheel so cheap, that's the way to go. Have fun!