Casio F91-W Custom Clear Case

This Project is a modification to the Casio F-91W by completely replacing the original case with a clear transparent resin 3D printed case. This custom case was designed to incorporate the original buttons, backplate, and back gasket.

The Clear Case with the Faceplate can be found here : https://grabcad.com/library/casio-f-91w-clear-case-v1-1

The Clear Case without the Faceplate can be found here : https://grabcad.com/library/casio-f-91w-clear-case-1

The sponsored PCBway link to manufacture is here : https://www.pcbway.com/project/shareproject/C_CN8W799384A_CNC_Case_3_64a9fe16.html

First Image :

The first image shows the tools used in this project. The tools are as follows : A Dremel, a 2.5 mm drill bit, a pair of needle nose pliers, and a small Philips head screwdriver.

Second Image :

The second image shows all the watch components laid out for assembly. Note that the gaskets needed for the buttons are not from the Casio F-91W. The gaskets used in this project came from this button replacement kit : https://www.ebay.com/itm/166838057561?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=a2dlshl2tt-&sssrc=4429486&ssuid=93sgdub8tf6&var=&widget_ver=artemis&media=COPY

Also minor note the watch module has been modified using the Sensor Watch Lite Board developed by Joey Castillo and his company Oddly Specific Objects. Here is the link to their project page : https://www.sensorwatch.net/

Third Image :

The third image shows the types of screws that were used in this project. For this project the LYJEE M1.4*4 screws were selected based on how well they tapped into the resin case. The Screws can be found here : https://a.co/d/g86CPjy

The Fourth Image :

The fourth image shows the adhesive glue used to attach the clean faceplate onto the clear case. (This is not needed if you choose to work on the crystal less clear case). The glue can be found here : https://a.co/d/014dPwl

Prior to this step the watch back plate needs to be removed using the screwdriver and removing the four screws on the back. After that the gasket and the 593 watch module need to be removed from the watch.

The first step is to remove the watch crystal. This step and subsequent steps can be skipped if you are working on the crystal less model.

The First Image :

The first image shows the casio F-91W being heated with a hair dryer on the HIGH setting. Apply the hair dryer for 10 minutes with the faceplate touching the flare surface and the hair dryer applying the heat from the back of the watch. Leave about a centimeter gap between the end of the hair dryer and the back of the watch.

The Second Image :

The second image shows how to remove the watch crystal after the 10 minutes have elapsed. Warning after the 10 minutes the watch body and strap will be very hot. In the image an orange cloth was wrapped around the watch as the two thumbs applied outward pressure on the back of the faceplate. You should hear and feel a pop after applying adequate force. Check to see if you damaged the crystal upon removal around the edges.

The Third Image :

The third image shows a 3D printed version of the watch using PETG (black plastic), the removed crystal, and 400 grit wet sand paper. This next step can be skipped upon slight modification. The reasoning being that the original model’s crystal cavity is slightly shorter than the crystal height. This makes assembly impossible unless the crystal height is reduced.

The Fourth Image :

The fourth image shows the first movement in reducing the crystal height. Start by wetting the sandpaper and placing it on a flat surface. Then press the faceplate down as parallel to the surface as possible and slide it to the position shown in the fifth image. Repeat this for 5 passes for both the bottom and top side of the faceplate and test the fit. For me around 20 ish passes on top and bottom were adequate for the cavity compensation. As shown in the sixth image.

The Seventh Image :

The seventh image shows the Casio F-91W without a faceplate. This will be needed in the next section where the buttons will be extracted from the case.

After the crystal has been removed the paint can be stripped away using a guitar pick and scraping it under water. Once the crystal is clean it can be inserted into the clear case. To insert the clean crystal apply a bead of B7000 glue around the exterior of the outer cavity edge. Once the glue is set press the crystal in and clean any excess that spill out from the edges. Let the glue harden for 24 hours before testing the water resistance.

To remove the buttons simply use the tip of the pliers and press on the back of the button through the case. 

The First Image : the first image shows how to push the button. 

The Second Image : the second image shows the how the button should look like after it is out. 

The Third Image : the third image shows how the button just falls out if you tilt the case in that direction.

The First Image :

The first image shows the removed buttons and three gaskets obtain from the button kit.

The Second Image :

The second image shows the gaskets on the three buttons. To put the gasket on the button simply push the gasket from the back of the button through to the front of the button.

The First Image :

The first image shows the process in which the button holes were drilled out. This step is nessisary even though the model has printed holes the printed holes are not the same dimensions as the buttons and therefore needed to be cleaned up using a 2.5 mm drill bit. Note that the drill bit is attached to the Dremel but the Dremel is not ON. This was done to have better leverage when manually rotating the drill bit through the printed holes.

The Second Image :

The second image shows how the holes should look after being cleaned up by the drill bit.

The First Image :

The first image shows the tapping of the case rear holes for mounting the backplate. To tap the screws simply screw them in using a screwdriver. Some resistance will be met but it should be relatively easy. After taping remove the screws slowly and clean the holes out.

The First Image :

The first image shows the first step of assembly, insert the 593 module into the clear case. after that carefully apply the back gasket onto the watch case. Once the gasket is in place screw on the back plate tight. After the back plate is attached insert the buttons from the outside inward until all the gaskets are inside the button holes. This concludes the watch case assembly. The only thing left to due is add the strap. Note that the spring bar holes are small and were designed to incorporate the quick release spring bars and not traditional spring bars.