I have several packets of staffs labelled "Hamilton 18 SDS"
With out taking them out of pkg to measure, any one know what movement they are for.
Mel

My 1936 Hamilton Parts book lists for all 18s watches Staff part numbers; 127-Single Roller, 126-Double Roller

My parts book agrees with Dave, but my Handy Manual (and previous experience with a 940) show that they have small collet and large collet versions of each. I'm not sure how SDS fits that, though. I've seen SRSC, SRLC, DRSC, DRLC other places I think.

If I have the courage to open the packets, what are the dimensions I should measure
126 127
Total Length
Balance Dia
Roller Dia.
Hairspring Dia
Length from Sh to tip
Hub Length
Pivot Dia

Mel

"SDS"
S= Small Collet?
D= Doubler Roller?
S=?

Melvin, here is a link to the the "Helping Hands" topic on American Pocket Watch Staff Dimensions that John Duvall posted several years ago. It includes a link to a list of the staff dimensions for part #'s 126 & 127.

Staff Dimension Topic

Hi Robert et al
If I understand it correctly the 127 are Single Roller and come either Large collet or Small collet. And the Small collet come either 0.11 OR 0.12 pivot.
The 126 are Double Roller and come in either large collet or small collet. And the small collet comes either 0.11 or 0.12 pivot.
The dimensions in the roller (1.12/0.71) indicates a stepped roller area(?).
Have I got that right?

From Table
(Length)(Bal)(HS)(ROLLER)(HUB)(PIVOT)(...)(...)(P/N)
(5.82)(1.28)(.97)(1.12/.71)(.87)( .10)(DR)(LC)(126)
(5.82)(1.28)(.77)(1.12/.71)(.87)(.11-.12)(DR)(SC)(126)
(5.44)(1.28)(.97)( .71)(.87)( .10)(SR)(LC)(127)
(5.44)(1.28)(.77)( .71)(.87)(.11-.12)(SR)(SC)(127)

These measure 5.81/1.28/.97/1.12/.87/0.10
So they are Hamilton 18s #126 DR LC pivoto.10
Thanks to all

Woops 5.82 not5.81