V3.3 builds on top of the initial design for V3 finger design. The aesthetic design remains the same, but many optimizations have been made to the design to improve overall printabilty and assembly. 

Subtle features have been added within the model to reduce effects of 3D printing imperfections from impacting the fitting of joints. Rounding to edges have been added to reduce overshooting artefacts on surfaces from ghosting, ringing and nozzle pressure build up, and seam adjustments have been added to avoid seams being placed between joint surfaces. Clearances on the joints are still fairly lenient to allow for easier printing, but clearances may be reduced down to 0.1mm if required.

For a two joint finger, fingers require the use of 1.75mm and 3mm nylon filament to act as pins between joints. Nylon should ideally be used as it provides a low friction, low wear joint. The flexibility of nylon also allows for a springing effect of joints, as well as to aid with friction fit joints through deformation of the material. 

For closing actuation, fingers are actuated through a single cord of 0.5mm to 0.8mm diameter braided fishing line attached using a screw. For opening actuation, fingers are opened using an elastic material attached on the back side. The method of attachment of the elastic material allows for a number of options that available or easily accessible. Elastic cords can be used through tying knots at ends, and elastics can be printed or made through casting, injection moulding, die cutting, etc. Detachable cords also allow for easy replacement or disassembly of fingers.

The positional consistency of V3.3 finger has been improved for better grasping when used in tripod or pinch mode. Ideally for the current design of ARX Hand, the actuation force should be directed towards closing the knuckle joints without closing of the middle-proximal joint. Because of the under actuation of the joints, the closing of joints depend on the resistance of actuating each joint and how the fingers may be obstructed. If there's even actuation resistance between each joint, the joints will close evenly with the middle-proximal angle roughly equal to the knuckle angle. But due to how the fingers are angled and the effective leverage distance on contact upon closing in on the thumb, actuation force will be directed towards the middle-proximal joint 

Fingers can be printed without supports for little to no post processing needed for assembly. Supports may however be required if there isn't enough adequate cooling for overhanging areas. Additionally, TPU grips can printed to improve functionality of fingers with grasping objects.

Features
- Easy assembly and disassembly
- Flexible choice of elastic materials
- Interchangeable system
- Durable and impact resistant design
- Improved positional consistency of finger actuation
- Low post clean up requirement
- Cleaner prints with adjusted seam placement and rounded edges

Further work
- Printed TPU pads don't provide a significant amount of grip so grip needs to be improved
- Find what could be used alternatively for grip on fingers
- Look into possibilities with printing or casting finger tips out of TPU
- Look into if there are extension springs that can be used as an additional option to elastic cords
- Possibly implement features to reduce play in joints
- Improve placement of the end of the tendon cord