You can tell that a watch case back is a screw down case by looking at the back: if it has notches regularly placed on the case back, that is an indication it is a screw down watch.
Before you start, you may need to remove the watch band so that your tools can fit on the watch back. See our How to Change a Watch Band article for help with this.
Once you have the tools you’ll need handy, you’ll want to place the watch case in the watch holder to protect it and hold it steady during your work. Open the pins of the holder wider than the size of the watch case, put the watch in the case and tighten the holder until it holds the watch case securely.
Next, take your Jaxa wrench and determine which type of tips would best fit the notches in your case back: test the free tips in the notches until you find the pair that fit best. Then, once you know which tips you need, insert them into the wrench.
Using the adjustable wheel control on the top of the jaxa wrench, adjust the opening between the notches until all three tips fit in the notches on the case back. Here’s a handy tip: always match the bottom notch first and then adjust the upper two.
When the tips are securely in place in the watch case back notches, you can begin to unscrew the watch back. Grip the watch holder to keep it from moving and begin turning the handle of the wrench counter clockwise to open the watch case.
Once the case back has been significantly loosened, you can remove the wrench and lift the back off with your fingers. Now you are ready to change the battery or complete your watch repair. When you are finished, you can learn How to Close a Watch Back with a Jaxa Wrench here.