Print your own flexible watch group. Fantastic for digital and other types of watches. Use the openscad files to personalize the band to the width and length you need.
My leather watch band broke and I wanted to replace it with a 3D printed band, but it needed to be flexible. After much experimentation, I discovered that the most flexible band consisted of one layer oriented parallel to the band length. This design is simple, but nice looking and fast to print. The buckle is super simple and an obvious place for improvement, even though it seems to work good as is.
NOTE: I have only printed this in ABS, and will update once I know how it works with PLA.
The included . stl files assume the following:
- The band needs to be about 150mm long (e.g., the wearer has a ~177mm wrist circumference and the watch is ~25mm wide)
- The watch band width is 19mm
- The watch band pin is about 1.8mm diameter
- The watch band attachment height (the height of the watch piece where the pins attach) is about 5mm
- The printer is set to one layer height of .4mm (.3mm ought to be good - the important thing is that the strap part print in one layer).
If all of this is true, skip to step 5. Otherwise, you will have to customize the included openscad files.
Instructions (all sizes in mm):
1) Measure around your wrist and subtract the size of your watch (the distance between where the two bands will attach). The . Stl files here will provide you 152mm or 6" of strap length (maximum) when fastened. If your watch is 25mm long, that means it will match a 177mm circumference wrist. If your wrist is larger or even smaller, you will have to download the openscad files and increase the straight_length factor. You can increase the variable on only the hole side, or both sides as preferred. The sum of the straight_length variables from both sides along with your watch length should be slightly more than your wrist circumference.
2) If you will need to change the layer height to match your printer's layer height setting (e.g. if it's more than .4 or less than .3mm), change the height factor in either scad files. You want the strap part to print at the first layer only.
3) Determine how broad your watch band ought to be. Check it is ~2.5mm less than the distance between the pin holes on the watch. If you make a band that is exactly the distance between the pin holes, good luck getting the band off again. Change the width factor in both scad documents as needed.
4) Compile and export the . stl files.
5) IMPORTANT!!! Open the . Stl file on your 3d printing program of choice and look at the Gcode visual preview. Make certain that the infill in the first layer that will print the band is oriented in exactly the exact same direction as the band itself (ie, parallel, not perpendicular to the length of the band). If necessary, enter your slic3r/skeinforge settings and rotate the infill to match the orientation of the band. Note only the bottom layer that prints the band needs to be oriented this way. The other layers can be virtually any orientation.
6) Print! But before you print the buckle side, have a bit of paper that is slightly less than the width of this band ready to go. After the first 3 layers print (and before the 4th layer), put this paper involving the buckle supports. This will prevent the buckle top from entirely collapsing on the band if your printer can't bridge the distance (mine couldn't).
7) I discovered that occasionally slic3r has trouble getting 100% infill in the group, based on orientation of this band (directly vs 45 degrees). If you find some small gaps between the infill, wetting both sides of the sepration with acetone and then pressing them together softly can chemically weld them together.
8) See if your pins fit. If not, you may have to drill out the pin holes. I discovered a 5/64" piece was perfect.
9) Insert the pins and attach the band. If the part of the band holding the pins is too thick (meaning that the pins do not get close enough to the watch body to fit into their holes), you may have to file off a bit of plastic from the outside of the pin-holder component of the band closest to the watch body.
10) After the strap is on the watch, feed the band with holes through the buckle and snap the bump on the buckle side by means of a strap hole. If the bump is too small, you may have to adjust the buckle_hole_size factor in the scad file (increase it on the buckle side, or reduce it to the hole side). If the bump is too large, you can file it down. You want it to be comfortable enough that it snaps into position.