The first step in learning more about your watch, or trying to repair your watch, is to get the darn thing open. This can be a very tricky and frustrating operation. I should note that "learning" more about your watch starts inside the case. Any markings to determine what the case is made of will be stamped on the case. Any markings to determine the quality of the "movement" (or the actual workings of the watch) will be stamped on the movement. In pocket watches, the case and the movement almost never have anything to do with each other. It is very common to find an expensive solid gold case with a low quality movement inside. Even more common is finding an inexpensive gold-filled (gold plate) case with a fabulous high quality movement inside. The reason for this is that the watches and the cases were usually made by different companies. A standardized sizing system allowed this to be possible. The companies would supply watches and cases to jewelers who would "custom fit" a watch for each customer. Sometimes the customer would opt for style. They would spend the extra money to have a solid gold case, but would "cut corners" on the movement to save money. Other customers wanted a reliable quality timepiece. They would buy a high grade movement not being overly concerned about the case (also to save money). Once the selection was made, the jeweler would piece the two together very easily, and the customer would be on their way home with their new watch. This is why it is so important to open the case to see what we have. You can't usually judge a watch by the exterior...it can be deceiving. Pocket watch and wrist watch cases have been designed in MANY MANY different ways. I will try to describe all of the ways to open watches, but only from experience will you truly learn how to "crack every nut".
STEP ONE INSPECTION:
Make sure to inspect your watch case very carefully and make note of any hinges, raised lips, notches, or pry areas that look like that is where a tool should go. Then match those characteristics to those described below.
SNAP BACK CASES (POCKET and WRIST WATCHES):
This is a type of case where the back and bezel (which is the metal ring that holds the glass) are simply snapped in place like a Tupperware container. It is easy to tell if this is the case. There will be a raised lip indicating where to place a tool for prying, but nothing else. No hinges. Tank wrist watches are almost all snap backs. If a lip or notch is not present, the case is probably not a snap back case and no attempt should be made to pry off the case back. Before putting one of these cases together again, carefully examine the mating surfaces, especially at any "corners." Usually there is a small locating pin, and corresponding hole, to assist in determining the correct rotational position for the back cover. Many snap back cased, and wrist watch cases are impossible to open without using a DULL tool. You can try to put a fingernail in the back lip/slot and running it around the edge of the case. There are tools specifically made to be case openers. A case knife can be very helpful in opening many different watches. They aren't sharp enough to cut you, but are designed with a nice rounded edge that makes opening a case a breeze, and won't damage or scratch the case of the watch. I would highly recommend this purchase... I once slit my thumb open nearly to the bone using a sharp pocket-knife... what a lesson that was!
SCREW BACK CASE (WRIST WATCH):
Wrist watches also commonly have screw back cases. Unlike pocket watches that can be opened by hand, wrist watches have six notches around the edge of the case back. A special adjustable case wrench is required to open this type of case. You adjust the wrench so that the three teeth fit snugly into three of the grooves of the watch-back and turn counter-clockwise to open.
SCREW BACK & BEZEL CASES (POCKET WATCH):
This is probably the most common type of pocket watch cases around. The bezel (which is the glass side of the case) and the back is threaded in place and literally screws right off. These types of cases are identifiable by the fact that there are no hinges or raised lip areas. Under careful inspection there will be a very fine line of separation between the back of the case and the body of the case, and a very fine line of separation between the bezel (which is the ring that holds the crystal) and the body of the case. Look carefully for a small raised lip on either the back cover or bezel. This lip usually signifies where to pry with a case knife. If a lip is present on the back or the bezel, then it is a "snap-on" and not screwed on. If there is only one "fine line of separation", that between the bezel and the body of the case, then your case is a "Swing-out" case and the back will not screw off (see below). To unscrew the back of a Screw back & Bezel case, hold the watch dial down in the palm of your left hand, with the winding stem, more properly called the pendant, up against your left thumb. Much like the motion used when opening a jar of pickles, press the palm of your right hand down firmly on the back of the case and unscrew the back by turning it counter-clockwise.
HINGE BACK & BEZEL CASES (POCKET WATCHES/ some WRIST WATCHES):
Another very common style of pocket watch case is Hinge Back & Bezel case. Under careful inspection you will notice two tiny hinges. These are the hinges for the back cover and the bezel. The covers "snap" close. The hinges are typically located at the 6 o'clock position, but not always. Usually there is a raised lip indicating where to pry. First try to pry at this location with a finger-nail. If it doesn't open, use a case knife. A case knife can be very helpful in opening many different watches. They aren't sharp enough to cut you, but are designed with a nice rounded edge that makes opening a case a breeze, and won't damage or scratch the case of the watch. I would highly recommend this purchase... I once slit my thumb open nearly to the bone using a sharp pocket-knife... what a lesson that was! It's possible that there's an inner back that can be opened the same way.
Hunting Case differ slightly to Hinge Back & Bezel cases. These watches have hinged covers over the back AND the front of the watch case. When closed the crystal and the dial are protected by the front cover. This front cover can be opened by pressing down on the crown which activates a tiny latch. DO NOT PRY IT. The back cover can be opened by prying as mentioned above. When opening the cover of a HC watch, hold the watch in your right hand with the crown under your right thumb and with your left hand over the cover. Once the cover is released, ease it open with your left hand, preventing it from swinging open too wildly and damaging the hinge. When closing the cover, always press in the crown with your right thumb until the cover is firmly closed, then release the crown so that the inner catch, latches the lid in place. "Snapping" the cover closed without pressing in the crown eventually wears away the metal that the inner catch grabs onto.
SWING-OUT CASES (POCKET WATCHES):
The term swing-out refers to a type of case where there is only one way to access the movement... through the bezel. If you find that under close inspection, there is only one fine line separating the bezel from the body of the case, then this may be the type of case you have. These are cases where the movement is mounted on a ring which is hinged to the INSIDE of the case. There are only two parts to the case, the bezel (the ring holding the glass) and a deep back in which the movement sits. Look around the edge of the bezel. If there is a place for prying, then this bezel is snapped in place. If there is not, the bezel is probably screwed in place. In any event, remove it. You should now see the inner ring, hinged at the 12 o'clock position and a groove at the 6 o'clock location. Hold the watch, dial up, and pull the crown (winding part) out to the "setting" position. You will feel it "click". The movement is now ready to "swing out". Use a fingernail in the groove at 6 o'clock and lift. Do not use too much force. Most of the time it swings right out. Sometimes you will need to jiggle the crown a little to get some clearance.
SWING-OUT CASES (WRIST WATCHES):
Some older wrist watches have swing out cases as well. You will notice under close inspection of the back that there is a place for prying the back off on one side, and a hinge on the other. This was popular in the 1920's. When the back cover is snapped open with a case knife, instead of coming free, it is attached to a hinge like opening an old fashioned pill box. The movement is revealed and is also held in place on a hinge. Using a fingernail, you should be able to lift and swing it out.
"OPEN THROUGH CRYSTAL" (WRIST WATCHES):
On some wrist watches you will not locate any cover on the back of the watch. This will be very puzzling. It may or may not read "open through crystal" on the back. This is a type of watch where the case is one piece. The movement is actually held in place with the crystal. On these watches you will need a crystal lift. This contraption has about 50 grabbing fingers in a circle that can be tightened down over the edge of a crystal, and actually squeeze and constrict the plastic allowing it to be "lifted" out of the front of the case. The crown and the stem still hold the movement in place, but you will notice that the movement moves around and is almost "free". The winding stem on these watches are 2-pieces. One slides into the other and inter-lock. It is tricky, but if you try to lift the movement out while turning the crown, the two will slide apart and the movement will come free. If not, you can pry the crown out (the two part stems snap in and out of each other but sometimes break when this is done).
Sometimes you will find after opening the back of a watch that there is another cover or "door" inside. This is a dust cover. To reveal the movement, place a fingernail under the edge of it and it should pop open easily. This dust cover is designed to keep dust and gunk out of the movement. Try to keep it closed as much as possible.
NEVER, NEVER, NEVER FORCE ANYTHING. If the case you are trying to open is giving you trouble, bring it to a watchmaker and ask them to open it for you.