Part 1: Fitting a sapphire back and a new SS bezel
Copyright (c) February 17, 2000
G. Luppino
During the course of collecting these great watches,
I have been doing some customization. In particular,
I have added sapphire backs, new bezels, new dials
and hands to 321 movement versions, etc. What I describe
here is a particularly simple procedure that I WOULD
encourage people to "try at home." A lot of the fun
and satisfaction in watch collecting is amplified when
one "rolls up their sleeves and makes their timepiece
into the one THEY want to own and wear.
I will describe in great detail the simple process in converting
a standard Speedmaster moonwatch into one with a sapphire back.
This is extremely straightforward, but is not always as simple
as just screwing the new back in in place of the old one.
In this customization, I will also swap a new SS bezel
(from the 1957 re-edition) for the standard black enameled one.
The watch you will see is in my opinion the best looking
Speedmaster you can find. I did this particular customization
for another Timezoner. I hope he likes it!!
To begin, I swapped in a new SS bezel for the old one. The
most delicate step here it removing the old bezel without marring
it or the case. I use a soft-tipped tool (one of the Bergeon hand setting
tools with the nylon tip works well) that can be used to "pop"
off the old bezel. The watch is held against something firm and yet
compliant so it will not scratch the case or crystal. Placing the
watch more or less face down and putting the soft-tipped tool against
the underside lip of the bezel, you strike it with a small hammer
and the bezel will come right off. The new SS bezel is fitted
using a crystal press with a custom delrin "bezel press" die
that I made for these Speedmaster bezels. A simple squeeze of
the handle and presto, the new bezel snaps on and looks perfect.
I believe the standard moonwatch black dial and white baton hands
look really sharp with the SS bezel. Here is the watch with its
new, and unique, look.
Now onto the sapphire back. First, the old "First Watch Worn
on the Moon" back must be removed. One should use the proper
case opening tool to do this and to avoid marring the caseback.
After removing the caseback, you still cannot see the movement
because it is covered with a movement dust cover that also serves
as a magnetic shield.
The dust cover is friction fit over a small lip
on the movement retainer ring. It can be popped off by slipping
a very thin blade under one of the edges and simply prying it off.
It is generally only held very loosely, and will come right off
with no problem. The movement cover will not be used with the
display back. Now, adding the sapphire back would be a very simple
procedure if not for the problem with proper retention of the movement.
The movement retainer rings provided with the display
back versions of the Speedmaster and the movement retainer rings
for the standard moonwatches often differ in thickness (probably to
accomodate the anti-magnetic movement cover) and so if you just
screw on a sapphire back to the typical moonwatch, the movement retainer
rins will not seat against the edge of the sapphire back and movement
will rattle in the case. In order to resolve this problem, a small
spacer ring must be inserted that makes up the difference in thickness
between the two movement retainer rings.
First, the thickness of the proper retainer for use with a sapphire
back was measured. Then the retainer for the solid back moonwatch
was measured. The difference is 0.035 inches. This is the required
thickness of the spacer ring -- just under 1 mm.
The spacer should fit over the lip on the retainer where the
dust cover would normally go. The ID of the spacer needs to be 1.098
inches and the OD should be 1.160 inches. You can see this lip clearly in the
photo below. The spacer ring fits onto the ledge just outside the first
(inner) lip.
Making such a spacer ring is a simple job if one has the proper
equipment - namely a small lathe. You can make the ring out of
a variety of materials - SS, aluminum, or a machinable plastic like
black or white delrin. I chose to make the ring from SS so it would
be a good match to the watch movement and would not be visible
through the sapphire back. To make such a thin ring, you start
with some SS bar stock or better yet, SS tubing. You turn down the
outside diameter (OD) to the proper dimension, bore the inside diameter
(ID), face the edge, and then use
a parting tool to cut off the small ring at the required thickness
of 0.035 inches.
My lathe setup is shown below. It is substantially more elaborate
than is needed for this task, but illustrates the process.
The SS stock is held in the vise (6-jaw bezel chuck). The OD is turned
using the tool in the front of the double-tool cross-slide.
The boring of the ID is accomplished with the
boring head mounted in the
6-position turret.
On the closeup photo below, you can see the parting tool on the
backside of the double-tool cross-slide. The parting tool is
held "upside down" so that the cutting occurs with the spindle
turning in the same direction as before.
Once the ring is parted off and deburred, it is cleaned and
can be test fit onto the movement retainer ...
... and installed into the movement.
Now the watch is ready fo the installation of the sapphire caseback.
Before beginning, be sure to
inspect the gasket to insure it is seated properly, and that it is
not nicked or damaged. Be sure no debris has fallen into the movement,
and finally, you can gently screw on the sapphire caseback (with fingers
first, so that you don't cross-thread it) and then tighten it using the proper
tool ...
... and Voila! -- you have a customized Speedmaster. In this case,
one that is NOT available from Omega.
Later, I'll show the steps in fitting a dial from a 1957 re-edition onto
an old 321 movement, and some more customizations on the wonderful
old Speedies with the 321 movements.
