Introduction: Ukrainian Scissors
When cutting hard cardboard or like haven't you ever asked yourself:"Why isn't the biggest mechanical advantage of the scissors where it's needed most of all - at their tips?"
The Ukrainian Scissors leave the above question in the past.
This invention is especially great for craft, DIY, repair, home improvement, and other applications (e.g. science, medicine, even a manicure) where precision, easiness, and convenience when working with tough materials are critical.
Compared to regular scissors (the least mechanical advantage is at the tips) and the "Swiss scissors" (mechanical advantage along the blades is all the same 1:1, seemingly not enough for the hard cardboard), the Ukrainian Scissors' principal innovation is the biggest mechanical advantage being available where it's needed most of all - at the scissors' tips. This is a huge advance by itself.
The main features of the Ukrainian Scissors are the following:
1. The biggest mechanical advantage (7:1 in the working prototype) is where it's needed most of all - at the tips of the scissors as a virtual fulcrum is in front of them (unique ergonomic feature, great for precision work like craft, etc.);
2. Minimal slipping risk due to a narrow gap (small cutting angle) all along the blades (safety and convenience);
3. Much shorter than regular scissors with same maximum mechanical advantage and blade length, user's hand is much closer to the working area (precision, convenience, storage);
4. The tips are the slowest moving parts of the scissors what is great for precision work.
Watch an animation above and see the steps below to better understand the idea behind the Ukrainian Scissors and possibly to make a pair of them for your personal use.
Step 1: Make the Blades, Guides, and Washers
The drawings above are for guidance only and can be adjusted for your preference (all dimensions are in millimeters). In this embodiment all the paired parts of the scissors are identical for simplicity. The blades can be laser-cut from 3mm steel. The springs can be cut from any appropriate spiral spring (either round or rectangular). You can also use any appropriate screws (M3x0.5 in this case) from the box to attach the guides to the blades. For simplicity, the guides can be made cylindrical, btw.
Step 2: Assembly
Assemble the parts as shown on the image above. To provide better contact between the blades' edges the contact elevations can be formed on the blades by removing some material from the adjucent areas, as shown on the image above.
My first (very) rough prototype is shown on the photo and video. Yours can be much better!