Analysis

Requirements

Pruner Requirements:

Capable of cutting a 1.75" branch
Cutting device must be at least 30” away from trigger
Total weight must be less than 3 lbs.
All components must cost less than $500.00

Housing/Ergonomics Requirements:

Housing component must weigh less than 1 lbs alone.
Housing must withstand 440lbs of torque (power of the drill).
Housing must include two handles for better ergonomics.
Housing outside diameter must be within 1 1/4”
Housing must assemble in less than 6 minutes
Housing must be coated with a rust resistant
Housing components must cost less than $200.00
Handle diameter must be less than 1 ½” in in diameter (removed for prototype)
Housing must prevent the motor from heating more than 115 degrees Fahrenheit (typical max heat for a power drill)

Approach

Performance Predictions

Pruner Housing

The pruner housing is expected to meet all performance requirements. Not only is the housing expected to weigh less than the very low required weight allowance. But, the housing is also expected to hold all components inside the pruner and be used as a guidance tool for better performance. At the end of the project the evolution between the previous pruner housing created by a CWU student and the new pruner housing will be clear.

Pruner

In order to improve on the current industry design the team focused on two major aspects for the newly designed pruner. First, was the overall weight, the Tree-Lion pruner weighed 2.1 lbs without the motor. Therefore the team decided to focus on using all lightweight materials and beat the current weight standard. The second requirement was to improve on the pruners cutting strength. The 'Tree Lion D45-700' was designed to trim grape vines, therefore to handle the extra force to cut through apple tree branches the components inside of the pruner had to be strong enough to break though branched that are up to 1 1/2" thick the cutting force to for that size branch is approximately 500lbf.

Housing

In order to improve the pruner housing, the goal alongside being under 1lb was to improve the size and ergonomics of the pruner housing. This included a more comfortable gripping size according to OSHA standards as well as having a lighter cutter housing and smaller motor housing