THis post goes along with one in the horological items to buy section. I want to get a staff to fit my Waltham 17 jewel Riverside model 1899. Serial number 11065589. It has a detachable staff with straight shoulders. It needs to fit a double roller with the bronze roller table and a steel safety roller. In order to get the roller table to fit properly, I need a shoulder that measures 1.31mm. Part number (part taken from Swigart book) 4860's shoulder is only 1.28mm although all the other dimensions are right on. The roller table is too loose to fit. Can anyone advise me on how to figure out what is the proper staff for this watch.

Scott,

The 4860 is the right staff. But the dimentions you are giving have me a little stumped (no staking pun intended). This watch should have a two piece double roller. Both the roller table and safety roller fit on the lower end of the balance. The dimension of .60mm is where they should fit. I doublechecked the dimention on a 4860 staff . Attached is a picture of the staff and the location of the three parts that fit onto it.

Usually a loose roller table indicates that past work was done with improperly sized parts and things were altered to fit. If such is the case, it is usually best to replace with new parts, which should be readily available for the 16S 99/08 Waltham.

Hopefully this is helpful.

PS

Our own John Duval published a great list of staff dimensions as part of his "Helping Hands Tutorial." Follow the link to find it:

Staff Dimension Link

Thanks Mike for the quick reply. I attached a pic of the original staff. Here is where the problem is. The staff in your pic is identical to the ones I have. Here is the way the balance was when I got the watch. The hub on the staff fit 1/2 way into the blued hub which is on the balance wheel. The exposed 1/2 of the staff's hub is what the roller table was on. This made the bottom of the blued hub the roller table seat and the hub on the staff the shoulder. Then the safety roller was put on. The hole in the roller table needs a 3.2 mm width to be set on properly, which was the width on the staff that was on the watch. My new staffs have a width that is 2.8mm. If it were too large I'd just take it down, but this leaves me wondering if the parts that were there when I got the watch were wrong. On your pic, the place where you indicate the location of the roller table is not the same place as where the roller table was on this watch. The roller table came down over 1/2 of the staff's hub and sat on the bottom of the blued hub. This made the blued up act as the roller table seat, and the hub on the staff, the roller shoulder. The copper roller table does not appear damaged or cracked, it just has a big hole. Please let me know if what I am describing could be correct on of these Walthams.

Here is a pic with the 4860 staff in the bal. It is in exactly like the orginal, but too narrow for the Roller table.

Scott,

I think I see where the problem might be. I will discect a M99 balance tonight to check on something. Does the balance have a serial number scratched into the bottom of the balance arm that matches the movement's SN?

Mike,
Yes, the number scratched onto the balance arm matches the movement. I really appreciate your help on this.

Part of the problem is that Mike's annotated photo is based on the way the 4861 (taper shoulder) staff is used. The "hub" of the 4860 sits just below the balance arms and uses a bronze roller table with a larger hole in it to fit this hub. Only the safety roller fits on the narrower portion of the staff. Scott's roller table is just as it should be (~1.3mm).

Scott - as far as your problem goes, you need a different sample of the staff. Some of the later reproduction staffs were not accurately made and did not have a large enough hub for the bronze roller. You may have to get several staffs to find one with the proper size hub.

Jerry is absolutely correct. I put together that photo without having the assembled balance in front of me and got the tapered shoulder staff and straight sholdered staff mixed up in my brain.

I disassembled a M99 balance and measured the hub and it was 1.31mm. I have a new one that is 1.31mm that should work. If you would like it, email me your adress and I'll send it out in the mail.

Sorry for making what should have been a simple answer confusing.

Corrected photo attached:

And a close-up of the real thing...

Thanks to both of you. Mike, I'll take you up on that offer, and I really appreciate it.