Link: Initial Product Assessment

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A by-now common device intended for the budget-sensitive clientele, the handheld line trimmer of Homelite®, model UT 15151 of the VersaTool™ line, operates within the design parameters that shape it as a consumer product. Indeed, through the insights afforded by a week-long preliminary assessment of the given product, an assorted array of attributes and kindred details, be they functional or otherwise, entered the consideration of a blueprint for approaching the product’s physical disassembly. Empirical scrutiny of the product, guided by an analytical mechanism steering the enterprise of reverse engineering, yielded revealing manifestations concerning the overall effectiveness and intricacy of its design. Among the subtler areas noted in examining the product, such layers of its design as its utility, the underlying physics of its operation, its mechanical complexity, the materials both constituting and cohering the varied components of its assembled form, and the ergonomic and economic factors that contribute to its marketable feasibility are all addressed herein.

Product Analysis

1.The intended use of the product
Commercialized as the contraption to supplement the typical lawn mower, the product functions, while operated by the user, to maintain an aesthetically pleasing, kempt lawn, or a variation thereof. It achieves this by trimming around hard-to-reach areas that are otherwise inaccessible to the blades of the conventional lawn mower, owing to either inhospitable terrain or other related obstacles.
1a. Is the product for home or professional use?
    In effect, the product falls into both categories; it is designed to accommodate the expectations of the pedestrian, lawn-caring
consumer as well as those for whom lawn maintenance serves as an occupational activity. Because it is highly available for
purchase and thus easily obtained, the product proves highly accessible to the consumer for whom the physical attributes of the
product—easily maneuverable, simple to operate, and designed with an economy of weight—are essential for recreational upkeep of the
lawn. Professional use of the product, on the other hand, can be regarded rather ubiquitous when considering the prodigious
sprawl today of occupational lawn care enterprises whose services are enlisted overwhelmingly by the suburban residence.

1b. What are the different functions of the product? In a word, the product materialized with the designed purpose of precisely, swiftly, and efficiently trimming grass, weeds,
and other undesired plants situated in terrain not conducive to the use of a lawn mower or a comparable grass-cutting machine.

2.The product's mode of operation
Generated by the internal combustion engine fueled by gasoline, energy transfers down a drive shaft leading to the cutting head, which rotates at high revolutions per unit time while receiving a sustained flow of the said energy. The rapidly rotating mount provides the means for the cutting line to scythe grassy terrain as the line is held taut by centripetal force.
2a. What types of energy are used?
    Firstly, the user must be considered, as the product cannot operate without such input.  That is, by pressing the primer several
times as directed by the product’s manual, the user applies mechanical energy; thereafter, the user pulls the starting cord whereby
the spark (electrical energy) necessary for ignition is created. Apart from these stages of human involvement in generating energy
prior to the ignition of the product, no other external contribution of energy influences the combustive imbalance of the engine and
the energy produced thereby. In particular, the combustion consumes the supply of fuel, a process involving chemical energy,
and creates pressure that in turn generates mechanical energy. This mechanical energy affects the entire product, but it is
specifically its transmission across the metal linkage leading to the cutting head that supplies the rapid gyration, and the
vibrational sensation created by the transmission of mechanical energy throughout the product as well. From all this activity
involving energy transfer and conversion results thermal energy; this is realized or sensed by the user in the form of heat, or
infrared electromagnetic radiation.

2b. How are these different energies transformed and modified? Effectively detailed in the response to the foregoing query, the following offers the synoptic, due response for the query
particularly addressed herein. In brief, the trimmer, powered by the mechanical energy generated by the internal combustion that
itself is fueled by the gasoline stored in the fuel tank, serves its purpose when pressure is created inside the compartment that
thrusts force outward, leading to mechanical energy. Subsequently, this mechanical energy is transferred through the metal linkage,
or shaft, connected to the cutting head and translated into the end result of the entire energy-producing mechanism: rapid rotation
of the cutting line.

3. Operational product
As the group failed to secure the gasoline necessary for the engine’s ignition, it remains undetermined as to whether or not the product operates in the present state under assessment. Testing of the product is projected, however, to be conducted within a weeks’ time into Gate II of the Reverse Engineering Team Project.
3a.  How well does it run?
     Consonant with the foregoing, a response here proves inapplicable.

3b. If there are any problems, from where do you think they arise? Although lacking the test for ascertaining whether the product operates upon user input for ignition, the group can form
rational assumptions and speculations as to the factors that may affect, and thus compromise, the operation of the product. Such
factors to be considered include the thoroughly used, somewhat corroding condition in which the product currently lies, and the
lifetime of the product, which was manufactured in 1999.

4. Complexity of the product
Defined as a qualitative measure of the extent to which association or relationship of components and the caliber of their functional sophistication deliver a desired end through an interconnected, interdependent configuration, complexity proves comparatively marginal for the product in question. As a gas-powered, hand-held device that incorporates a flexible cutting line to realize its intended function, the Homelite® Line Trimmer consists of components that fall short of qualifying it as complex a machine as, say, a high-end lawn mower designed for the lawn-caring consumer market.
4a.  How many components are used?
The components, fifteen (15) in total, of the product are listed thus:

1. Rotating cutting head
2. Long shaft
3. Handle fitted with rubberized grip
4. Shoulder strap
5. Monofilament (absent when product was first received in lab, as it was presumably broken)
6. Internal combustion engine
6a. Piston Cylinder
6b. Piston and rod assembly
6c. Assembly of cylinder encasing
7. Electric motor powering the motor head
8. Deflecting flap
9. Starter cord
10. Screws and Hex nuts
11. Fuel Tank
12. Muffler
13. Two-part plastic encasing/housing for the engine unit
14. Detachable air filter
15. Crankcase assembly

4b. How complex are the individual components?
Aside from such ergonomic components as the handle fitted with a rubberized-grip and the accessory shoulder strap, the
components powering, transmitting and delivering the output of the machine per original design adhere closely to the qualitative
measure of complexity as previously defined. Indeed, for a machine designed to be reliably serviceable, the most complex feature
may very well be the internal combustion engine block, the heart of the product.

5. Materials used in the make-up of the product
The materials constituting the assembled machine are: for energy-generating components, steel, of a grade still to be determined; heat-tolerant plastic compound for the fuel tank and handle; nylon for the starter cord; rubber for the grip fitted to the handle; and copper for the wires attached on the central unit—the encased engine block—of the product.
5a. What materials are clearly visible?
    The steel comprising the deflecting flap, screws and Hex nuts, and the shaft linking the engine to the rotating cutting head;
the plastic constituting the fuel container, the handle and the rubber of its fitted grip; and the nylon for the starter cord are
all visible on the assembled product.

5b. What materials are present but not visible?
Among the few materials that elude detection or are concealed by the plastic encasing, are the steel used in the manufacture of
the internal combustion engine block and its component piston cylinder, and the lubricant(s) applied to the internal parts configured
throughout the product.

6. Consumer satisfaction with the product
In light of its economy of weight, relatively low cost among competing brand names, the market’s extensive exposure to line trimmers manufactured by Homelite®, and the overall durability of Homelite® units, consumers’ behavior in the sector of lawn–care products favors the Homelite® model under consideration.
6a. is the product comfortable to use?
Comfort can be measured by the presence of the following: a rubberized handle for firm grip, a shoulder strap for withstanding
the weight of the product while operated by the user, and the size of the product, which distributes comparatively well over nearly
six feet in length.

6b. Is the product easy to use?
After the user achieves ignition of the engine, the product can be applied with a relative ease that does not, to any marginal
degree, require skill in operating the product. Aside from a throttle on the underside of the shaft, nothing else requires the
attention of the user in terms of operating the product, other than, of course, exercising caution in the manner in which the trimmer
is used.

6c. Considering it requires regular maintenance, is the product easily serviceable?
Designed to contain easily serviceable parts that are readily accessible to the user, barring any intervention from tools, the
trimmer requires periodic checking and adding gas to the fuel tank, and the regular changing of a detachable filter and a spark
plug, which is located immediately atop the engine block encased in the plastic emblazoned with a identifying two-toned coat of the
Homelite® insignia.

7. Existing, marketed alternatives to the product
As examples for purposes of comparison, the alternative contenders currently on the market are the 25-cc (cubic-centimeter), two-cycle, gas-powered Weed Eater® Featherlite Trimmer™, and its counterpart, the 25-cc Craftsman® Gas Line Trimmer. To be sure, both products bear close resemblance to the UT 15151 Homelite® VersaTool™, with the engine size and overall length actually identical to that of the Homlite®.
7a. What are the differences in cost?
On the issue of retail, pricing of the UT 15151 Homelite® averages to $59.99, whereas the Weed Eater® model amounts $94.99, with
the Craftsman® version registering still a higher price tag at $119.99.

7b. What are the advantages?
Contrasted against leading brands, the Homelite® proves less expensive and, particularly with respect to the Weed Eater® and
Craftsman® versions noted above, it is substantially lighter, and therefore highly maneuverable for a product of its size. Unlike
most gas-powered trimmers, the Homelite® only requires gasoline as its fuel intake, not a mixture of oil and gasoline. This feature
is, of course, attractive to consumers who intend to use the product purely for seasonal trimming and either are not inclined to
bother mixing oil and gasoline to the requisite ratio or merely lack the knowledge in how to prepare such a mixture. Ostensibly,
the design of the utility of the product targeted the typical homeowner as its consumer base.

7c. What are the disadvantages?
According to online, consumer-posted reviews, the product is “difficult to start” as opposed to Craftsman’s® “Pull-Lite Start”
feature, which allows for easier starting. Moreover, the analyzed Homelite® product contains a standard line feed that incorporates
a “screw-in feature,” whereas the Weed Eater® is equipped with the “Quick Snap” 10-second spool replacement feature, and Craftsman’s®
product employs an automatic feeder.

Concluding Remarks

Without disassembly, the analytical assessment applied to the UT 15151 Homelite® VersaTool™ line trimmer indicates and anticipates, to as accurate a degree as permitted by the extent of the assessment, the internal workings of the product and the various points of the customer’s interest discussed above. In light of the road of travail that lies ahead, the product under consideration has received detailed inspection of the elements of its design. Such preliminary measures will indeed ensure effective disassembly and facilitate the subsequent reassembly, thus allowing for a cautious, but far-sighted, approach to reverse engineering what may be construed as a mere consumer product.

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Reverse Engineering Team Project: Homelite® VersaTool™ Line Trimmer (Group 29)