Please help with identiying Elgin movement

[Arcticboy]

Hello,

I am in desperate need of understanding how to find the right balance staff for this movement:

Elgin National Watch Co.
Grade: 74
Manufacturer: Elgin
Movement Serial Number: 3264438
Model: 5
Class: 10
Estimated Production Year: 1889
Size: 18s

But furthermore we could we some help in understanding how to understand... The size (18s) seems to yield many different staffs. But the grade (74) does not seem to be recognized as id. Can someone offer some advice to a rookie?

All the best!

 

[Dave Coatsworth]

Your grade 74 uses the #857 staff. There are 4 variations of this staff and, unfortunately, the Elgin material catalog does not give much clarity on which variation is used in a particular grade or serial number.

First, we have "old style" and "new style". The difference between OS and NS is simply the overall length of the staff. OS staffs are 5.97mm long and NS staffs are 6.1mm long. For each of these, we have "long hub" and "short hub". This is simply the length of the hub. LH hubs are 1.51mm and SH hubs are 1.28mm long.

Elgin does indicate that the cutover between OS and NS is 3,000,000. Yours is so close to this cutover that I would definitely try to measure your old staff to verify. I understand that one or both pivots may be broken off, but perhaps you can estimate their length when measuring.

FInally, staffs come with different pivot sizes. If you have a good pivot left on the old staff, you can simply measure it. If not, you will need to measure the balance jewel hole. Possible pivot sizes for the #857 family range from 0.11mm to 0.14mm.

 

[John Runciman]

#857 staff

strangely enough that's my favorite balance staff number. I like to use it in lecturers or explain the people in discussion groups were part numbers don't always mean the exact part.

But the grade (74) does not seem to be recognized as id. Can someone offer some advice to a rookie?

maybe you need to look at the right place like this link
http://www.elginwatchparts.com/
as you can see a whole bunch of parts are listed including a balance staff number.

This is where having the right reference material is helpful. Like for instance because the question has come up quite a bit here and there I scanned in something there is your 857 balance staff.

Another thing very important when changing the balance staffs especially on vintage watches is a decent micrometer. That is because you should measure whatever you removed from the watch and compare it to whatever you perceive the replacement to be to make sure that everything is the same size. For a variety of known and unknown reasons there can be a size differences in the staff and it's much nicer to find out about them before you have something broken trying to drive it on for instance.