For some reason I’ve been thinking of the “double action” birdcage pull lately. I’ve used one a long time ago, and never really felt it contributed much to the vanish. Essentially what a double action pull does is give you more pulling power with less motion. It converts your motion 2 to 1, so you move one inch and the line moves two inches! It’s a great way to reduce arm motion for the vanishing birdcage, but adds complexity to the setup. Every bit of complexity you add, it’s another thing that can potentially go wrong. This may be the issue I have with it, the gain of having reduced motion isn’t worth the risk.
I haven’t used one in 15+years. Tonight I decided to make one, so I designed this one to be 3d printed:
Here’s what the insides look like:
There’s not really too much to it, it was a simple design and a quick print. Here’s the printed version:
There are a couple of things I want to change after printing the first one. The big change is that I want it just a little bit larger, so that I can fit a bearing inside for the pulley.
I’ll do a new design later today and hopefully I’ll nail it the second time!