Document Type

Undergraduate Project

Date of Degree Completion

Fall 2018

Degree Name

Bachelor of Science

Department

Mechanical Engineering Technology

Committee Chair

Dr. Craig Johnson

Second Committee Member

Professor Roger Beardsley

Third Committee Member

Professor Charles Pringle

Abstract

The H.F. Hauff Company invests a large amount of money in developing a quality pruner used in everyday agriculture. Modern electric pruners tend to be expensive while manual tree pruning is very physically demanding. A battery assisted pruner that is light-weight, ergonomic, inexpensive to build and powerful enough to cut branches that a nominal apple tree would possess is the direct affiliation that H.F. Hauff devotes its funding too. A team of engineering students from Central Washington University developed a product with consideration to each of these circumstances. Since hand drills have proven to be user friendly and of abundance in the agricultural industries due to the nature of machinery, the pruner is an attachment to a hand drill. An innovative self-reversing ball screw converts the rotational energy to linear energy driving the cutting blade utilizing a power efficiency of 90% and allows the drive train to reciprocate providing an unassisted return of the blade to the open position. Calculations prove that the average torque of a common drill nears 450 inch-pounds of torque fostering a linear force of nearly 1000 pounds. This Linear force satisfies the testing needed to cut a 1.5 inch branch which commonly occurs on the average apple tree. The pruner assembly costs $300 for material and manufactures using tool commonly found in industry keeping the price under $500 compared to competitive electric pruners upwards of $1000.

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