u/zdovz

I built a picture frame that changes from one physical image to another at a preset time, without a screen or microcontroller.

The quartz movement turns a capstan extremely slowly, winding fishing line. At the chosen time, the line pulls a zipper slider; the zipper releases a latch, and a 25 g falling weight draws the cover image down to reveal the second picture.

The clock isn't displaying time here—it's acting as a cheap, very slow timer. The reveal can be set hours, days, or weeks ahead, and most of the mechanism is 3D printed.

I'd be interested in this sub's thoughts on the clock side of it: is there a better way to couple to a quartz movement or protect it from excessive string tension? I currently keep the line load low and let the latch carry the release load.

Files and build notes, if anyone wants them: https://doubletakeframes.com/

I’ve created a slightly bizarre product: a mechanical picture frame that swaps between printed images after a set amount of time.

At its core, a small 3D-printed capstan fits onto the spindle of a standard quartz clock movement. As the spindle rotates, the capstan pulls a thread that triggers the image change.

In the picture:

• The gray piece holds the clock movement in place. Its projecting “boss” guides the thread and keeps it from escaping the capstan.
• The blue piece is the capstan in its installed position.
• The green line represents the thread. I currently use very thin fishing line to minimize diameter and friction.

The mechanism works reliably, but setting it up could be more user-friendly. Currently, the user must pass the fishing line through a tiny anchor point on the capstan, tie two overhand knots, and trim the excess. If it later needs adjustment or removal, the line usually has to be cut off.

I’m looking for either:

• Simple, mundane ways to make threading and tying this tiny line easier, or
• A clever, inexpensive, removable method of securing it without tying a knot at all.

The line is thin and slick, so anything based only on light friction may gradually slip. Space is limited, and the capstan cannot become much larger because the quartz clock movement produces very little torque.

Has anyone encountered a sewing, fishing, model-making, or MYOG solution that might fit this problem?

This little product demo explains the whole thing better: https://doubletakeframes.com/assets/videos/double-take-frames-demo-3x4.mp4