Flexible Watch Band with Soft Lock Clasp

Flexible Watch Band with Soft Lock Clasp

• TPU watch band is strong and flexible
• It is comfortable to wear
• Innovative “Soft Lock” clasp is easy to use, and secure

TPU is ideal for watch bands because it combines flexibility and durability, allowing for comfortable wear and resistance to daily stress. The smooth, skin-friendly surface and excellent rebound make it perfect for secure yet gentle modular strap designs.

But in the context of 3D printing, the problem is the clasp. TPU as a material is strong, but it is too flexible for most clasp designs that require rigidity. And using a different (harder) material just for the clasp makes the design much more complicated.

Soft Lock Security

This “soft lock” clasp design solves the problem. Printed entirely from TPU, the clasp automatically locks when you insert the tab. As long as the clasp is held tightly against your wrist, it stays secure. But it easily unlocks when you pull it away from your wrist and press the release lever. Slide the tab into the body and the clasp automatically locks tight—no fiddling, no fuss. It is simple, intuitive, and unlikely to pop open by accident. The snugger the fit, the more confidently it stays put. 

Sizing

Because it is made from TPU, the watch band flexes and stretches a little. This should make it easier to get a good fit. 

Five sizes are included:

• 136 mm - This is essentially a small
• 144 mm - An in-between size
• 150 mm - This is essentially a medium
• 158 mm - Another in-between size
• 165 mm - This is essentially a large. 

If you need one smaller than 136 mm or larger than 165 mm let me know. 

To make it fit well, you need to know how big your watch is by measuring the space between the lugs (where the spring bars attach). Then add the circumference of your wrist, and adjust for how tight or loose you like to wear your watch. 

As an example, my wrist is about 181 mm around. The lug-to-lug distance for my Apple watch is about 45 mm. I found the Medium size band (150 mm) most comfortable. So there is some slack in there. For my wrist, about 14 mm of slack was most comfortable (150 mm band plus lug-to-lug distance of 45 mm equals 195 mm, minus the circumference of my wrist). A small amount of math is required. 

Attachments

Print profiles are included for watches that take 22 mm bands, and for those that take 20 mm bands (I may do more widths later). 

The bands uses standard spring bars (double-flange spring bars) or quick release spring bars in the appropriate size. You should be able to use the watch bands for any watch (or other item that you wear on your wrist) that uses 22mm or 20 mm spring bars. 

A note about Apple Watches:

Apple watches are great, but odd, in that the fancy band connector (known as the X206 assembly) is more high tech than it may appear. I haven't seen a decent connector that is compatible with Apple watches and also 3D printable (they don't snap into place reliably). If you know of one, let me know! Because of this, I recommend that you use adapters that make a proper attachment to your Apple watch and provide adapter holes that can accept spring bars. These adapters are available in lots of places. But here are some links to get you started. 

Your choice of build plate makes a difference in terms of how comfortable the watch band is when worn against your skin. A smooth plate looks nice and feels comfortable. I tried to remove any other sharp edges from the model, so that it feels comfortable. 

TPU also softens a bit as it is warmed up by being next to your wrist. 

This model is adapted from oblivious's excellent Solo Loop TPU Stretchy Watch Band, which I recommend. I changed it from a single loop into a more traditional band - in two parts - with a clasp. And I softened some of the “sharp” edges (as sharp as TPU can be, which isn't very much) in an effort to make it softer against your skin. 

This model also owes a debt to Mistertech's Strap Buckle (No Supports), which appears to be based upon ChrisMUC's Buckle strong, easy printable supportless, from 2013! This is a fantastic and innovative buckle that is quite different from most of the snap buckles that you come across. I haven't seen anyone else use it with TPU. But it is a great solution for this watch band. I cut the top off of both parts of this model in order to make it slimmer. No one wants a watch band with a big buckle sticking out and getting caught on things. 

Thanks!