Cutter Housing
Central Housing
The three foot long carbon fiber tube did not require much alterations and truly only needed to be drilled in one spot. Although this would be a simple process on most materials, carbon fiber creates more difficulties because of the strength and fiber layout. In order to prevent splintering three actions were taken that can be repeated in future manufacturing processes. The first was to wrap the portion on the tube that was being drilled with electrical tape, this prevented splintering. The second was turning up the RPM's of the drill to over 3000, this created a smoother cut and prevented it catching on fibers during the drill. And the last portion was to drive the drill through slowly in order to prevent deflection in the drill bit.
Description
The pruner housing was manufactured at Central Washington University. Stock material for the housing were donated by Neil Hauff. Manufacturing took place by hand in the machine shop at CWU, and using the 3-D printer in the computer tech lab, also at CWU. While manufacturing took longer than expected for the cutter housing, the most difficult part to manufacture was the carbon fiber shaft, due to the fibers and strength.
Construction
During the construction of the cutter housing, many machining lessons were learned. In order to machine a part quickly and efficiently, the process of machining should begin in the design stages. After many failed attempts to design a suitable cutter housing in solidworks, it was thrilling to finally make something functional. Unfortunately, many dimensions were unnecessary and very difficult to machine due to the tolerances. Also, many adjustments had to be made in the final construction process when assembling the pruner because the fasteners used were to large to fit. Although over 60 hours were spent in the machine shop working on the cutter housing, nearly half of the time was unreported because it was time used to double and triple check the dimensions, construction steps, and tolerances before every machining process. For future pruner housing designers, it is strongly encouraged to create a cutter housing that is made out a single piece of aluminum to eliminate many of the concentric construction tolerances.
Motor Housing
As the motor housing was designed, it was obvious that due to the highly complex dimensions the best option for manufacturing the part was using a 3D printer, ABS plastic was used as the printing material. Although a more suitable material would be 6061-aluminum in order to provide greater strength while still maintaining light weight. One manufacturing caused requirement was that the motor housing had to be attached to the central housing with out the use of pins. Although an adhesive could have been used to bond the sleeve of the motor housing around the central housing, the two have actually been constructed together by using a press fit. A heat gun was used to heat the motor housing sleeve, once a temperature of about 150 degrees F, it was then expanded large enough to fit around the central housing. After the material had enough time to cool it was inspected for any stress cracking. Fortunately, there was no damage to the material.
MARKET
Central Housing Drawing
Cutter Housing Drawing
