One Minute Ball Timer

This ball timer is kind of like a digital hourglass, dropping one ball with each swing of the pendulum. Load it with up to 140 balls (.177 cal. / 4.5mm dia. BBs) to time up to 75 seconds. Enhance your game play by using it as a tension producing game timer. After it times out, pour the balls from the tray back into the top and give the pendulum a little tap to restart the timer. Once started, the pendulum keeps going because each ball gives a little push to the pendulum as it falls. (Note - the animation shown is in slow motion - the pendulum has a period of a little over ½ second.)

It requires one M3 x 15mm screw (Maker's Supply AA039) and one 623ZZ Bearing (Maker's Supply EA008). And of course, you will also need (up to) 140 steel BBs (.177 cal. / 4.5mm diameter).

Notes on Printing and Assembly

The trickiest part of this project is getting the track of the the spiral ball magazine to be perfectly smooth. In the 3MF file provided, I've added seam painting to prevent seams from appearing in the ball track, but I've also had to fiddle with other slicer settings to prevent Bambu Slicer from adding tiny gap fill segments which can create tiny blobs. (Hint to Bambu: please add an option to disable gap fill!)

After printing the top piece, insert one of your BBs, and sticking a small screwdriver tip in it's path, slowly let it lower down the entire spiral. If the ball hangs up anywhere, go in with a little scraping tool (like a screwdriver tip) and remove any tiny nits or blobs in the pathway.

After that, assembly is simple: press your bearing into one side of the pendulum. Insert the M3 screw into the bearing from the side with the open slot gap, and then put the tiny washer/spacer over the other end of the screw. Screw the pendulum into the hole in the stand. The spiral ball magazine should just press onto the top of the stand. If it is too loose to stay securely, add a drop or two of superglue. Finally place the tray at the bottom of the stand and fill the top with BBs.