A walnut cracker with two big handles - very strong. All crackers I saw had small or only one big handle. You always need two hands - therefore two big handles (diameter 85 mm) with a good grip. Very easy to use - also for people with little power or small hands.
If you have problems with too much friction, please grease the threads. This is good for the parts and you need only little power. Use food grade grease. After some time of use, the thread becomes more tolerance.
First Version: NC Bottom1.stl, NC Top.stl
Top and bottom without any pattern.
Update 2018 Dez. 27
Version 4.1: NC Bottom v4.1.stl, NC Top v4.1.stl
With new bottom part design. The lower nut shell crackes better.
Hole in bottem part is nearer to the bottom. Feed nuts and remove cracked nuts is easier now.
Needs 15% less material.
Ring pattern on top and bottom.
First Version and Version 4.1 are mixable.
Wallthickness 1.2 mm (3 x perimeters with nozzle 0.4 mm, 6 x top and bottom layers with 0.2 mm).
50% infill or more.
Use support only for opening in the bottom part, but you can try it without support too.
Thread has 40 degrees - no support here otherwise the surface gets rough.