In the photos above, the bent back and severely bent neck indicate that the workbench is too low. Adding extensions to the legs raises the bench and as a result straightens the back and improves the neck posture (still bent, but much better).
The photos above also illustrate the basis of the “elbow height rule.” In the left photo, the work is 3 – 4 inches below elbow height. At right, the work is at about elbow height. Thus, locating the work at about elbow height tends to put the back and neck in good posture. Elbow height provides a simple rule of thumb that is easy to remember and apply in evaluating work height.
It should be emphasized that the issue is the height of the work, not of the workbench surface. If the item being worked on above was larger, then the bench surface may well have been satisfactory at its original lower height.
Visual needs and strength requirements must also be taken into account. If you need to see up close, putting the work above elbow height can help (good arm support may be needed, plus magnification might help). If you need strength, especially a downward push, it is usually better to locate the work lower than elbow height. Thus, determining the best height is not simply a matter of looking up average elbow height in a reference book. Optimal height depends largely upon the nature of the task. You may need to set up a mock workstation and use trial and error to identify the best height.
Since the height of individuals varies, providing adjustment is important. Adjusting the height of the work is easiest when one person works at an individual workstation. Techniques to provide such adjustability is the focus of this page.
In cases where the work itself cannot be adjusted, such as when several people work on the same assembly line or when working at a machine that is too big to move, then usually the only way to make height adjustments is to use standing platforms for the person.
Adjust the work to fit the individual person, using the guidance provided in Principle 4 Heights i.e., usually elbow height but taking into account visual and strength requirements. Focus on the height of the actual work being performed, not the height of a bench surface.
One of the easiest ways to provide better working height is to use a “riser” or benchtop work platform. Almost everyone has done this at one point or another using a box or telephone books. The example above shows a temporary field station for an wildlife research task performed only a few times per year. In a more permanent work setting, a more professional-looking riser is probably warranted, but a milk crate is a good quick fix and it illustrates the concept. The point is that it is not necessary to raise the whole table — just using an inexpensive riser can provide a good work height.
Small riser Fixture (behind hand) used to raise product
These examples show a riser (left) that was made for a soldering task and a fixture (right) on an adjacent workstation that served the same purpose. Almost anything that raises the work piece can suffice.
Laboratory jack with added large surface Laboratory jack integrated into a solder workstation
Laboratory jacks are helpful if occasional minor adjustment is needed. The small scissors mechanism and knob provide for relatively easy changes.
Equipment that has been specially designed for this purpose is available on the market.
Simple blocks or leg extensionsHeight-adjustable computer monitor stands can also be used as workbench risers. They are commonly available and can be used for this purpose.
Another easy way to raise a workbench is to place blocks under the legs. It may not look elegant, but it can be effective when a one-time change in height is needed.
Similarly, it may be possible to replace the table legs with longer ones or add an extension to the leg. The example at the top of this page shows an example of adding leg extensions. Again, this approach is suitable when a one-time change is made for a particular individual or task.
When relatively frequent changes in the height of a work surface are needed, a comparatively inexpensive option is to use (a) an expandable leg in combination with (b) a set screw or bolt. Legs of this type are often fabricated with with two steel tubes of slightly different sizes, so that one slides inside the other. Usually a T-handle or similar lever is permanently attached to the set screw or bolt. In the photo above left, a set screw on only one leg is sufficient to provide stability. Above right, each leg must be adjusted separately.
The primary disadvantage of this approach is that it can be awkward to raise or lower the surface with one arm while holding the T-handle with the other. The best use is often when adjustment is needed for an employee new to that particular workstation, or at most, when a shift changes.
One of the great advantages of using a pedestal as the base for a workstation is ease of adjustment. It is mechanically much easier to raise and lower a single column than it is two or four legs. Barber stool bases are the most common example of a pedestal-based “workstation.” These bases are available without the stool on-line.
Die carts often use a single pedestal, but sometimes have additional side posts for increased stability. (See also die cart as workstation and pedestal examples in floor fixtures).
Hand crank pedestal base (www.alimed.com) Electric version
Pneumatic springs provide the height adjustment in most office chairs in use today and can also be used for work surface adjustment. All that is required for adjustment is to pull a latch, then gently lift up or push down. See sit/stand.
Hand cranks connected to hydraulic cylinders provide a common approach to height adjustment. The cost is somewhat less than powered versions and can be appropriate in situations where the need for adjustment is infrequent.
The workstations above are powered with electric motors and can be operated at the push of a button. The right-hand example shows a portion of a workbench that is powered adjustable, since only one task needed height adjustment and there was no point in powering the entire bench. Powered versions tend to promote use more than hand crank versions. Common vendors includewww.iacindustries.com, www.ergosource.com, and www.alimed.com.
Standard scissors lift as base for workbench Cars on scissors lifts on assembly line (accordion skirts around scissors mechanism to cover pinch points)
The above examples show hydraulic scissors lifts being used, one for a single workbench and the other for a car assembly line.
Poultry truck on large hydraulic cylindersThis example shows a poultry truck being unloaded at a processing plant. These trucks have multiple levels of cages for the birds that must be unloaded by hand. A tall work platform is constructed at a height for unloading the top level of cages. Once the top level is unloaded, the truck is raised so that the next highest level is at good working height. The truck continues to be raised until the lowest level of cages are empty.
A stump puts the anvil at a good height for this North American female blacksmith (lower than elbow height is appropriate here to enable more force). Arab blacksmith — There is a shortage of stumps on the Arabian peninsula, but a surplus of oil barrels. So the blacksmith leaves the anvil at floor level and recesses himself into the ground.
A workstation does not require height adjustment to be ergonomic. Indeed, an adjustable-height workstation that is used incorrectly may be very un-ergonomic. Anything that positions work at the proper height for the person and the task is ergonomic, even if it is as simple as a stump for an anvil.
Often, the most practical way to determine the best height for a given task is to create a mock workstation using some piece of highly adjustable equipment as a base. In the photo above, a lifter-transporter was borrowed for a few hours so that several employees could try working at different heights.
To be sure, it would be ideal to make all the workstations being planned highly adjustable. But to keep costs low, it can be helpful to narrow the range of adjustability that may be needed.
Furthermore, it can be helpful to get buy-in and input from employees to try a new concept before purchase decisions are made. Upfront involvement can increase acceptance and usability.
How electric flux work?
5 answers
Electric flux refers to the flow of electric field through a given area. In electric machines, such as axial flux rotating machines, flux-switching electric machines, and electric motors, the interaction between permanent magnets and coils generates magnetic flux. This flux is crucial for the operation of the machines, inducing alternating magnetic fields in transformer cores, aligning suspended particles in oil-filled basins, and modulating magnetic fields through ferromagnetic segments. The design of these machines involves strategically arranging magnets, coils, cores, and segments to control the electric flux and optimize performance. By manipulating the magnetic fields, these machines can efficiently convert electrical energy into mechanical energy and vice versa, showcasing the fundamental role of electric flux in their operation.
What is manual sand sieving?
5 answers
Manual sand sieving involves the traditional method of sifting sand particles by hand, which is labor-intensive and time-consuming. This process requires human effort and extended sieving durations. In contrast, automatic sand sieving devices have been developed to streamline the sieving process. These devices utilize motors, rotating shafts, sieving plates, and stirring rods to automate the sieving of sand. Automatic sand sieving equipment includes components like controllers, conveying devices, rocking mechanisms, and multiple sieving holes to achieve efficient and layered sieving of sand. The automation of sand sieving not only reduces the manual labor required but also enhances the sieving effectiveness by preventing the formation of sand lumps and ensuring a consistent sieving process.
What is an observation sheet?
5 answers
An observation sheet is a tool used in various fields such as healthcare and material inspection to record and analyze observations systematically. In healthcare, observation sheets help in documenting patient progress, medication administration, and clinical findings. They can also aid in reducing errors and improving efficiency by utilizing electronic formats that store observations in audio files converted to text. Similarly, in material inspection, observation sheets assist in examining material webs through guiding devices and cameras, enhancing the inspection process. Overall, observation sheets play a crucial role in data collection, analysis, and decision-making across various industries.
What are the potential academic and behavioral effects of using a clock in the classroom for Collège student?
5 answers
Introducing a clock system in the classroom for Collège students can have various academic and behavioral effects. Such systems can help in managing classroom schedules effectively, preventing distractions, and enhancing time management skills. Additionally, implementing innovative clock-based techniques like the "clocklight" from the PASS program can positively influence student behavior by reinforcing adherence to classroom rules and promoting group management strategies. Moreover, utilizing clocks with unique features such as small bells can add a visual and auditory dimension to time management, potentially aiding in maintaining student focus and engagement during lessons. Overall, incorporating clocks in the classroom can contribute to improved academic performance, better time awareness, and enhanced classroom behavior among Collège students.
How to create sample plyers?
4 answers
To create sample plyers, one can consider various methods and tools described in the research papers. One approach involves utilizing a sample polishing machine with a polishing disk rotating system, transverse and longitudinal displacement systems, and a polishing trough for efficient and convenient operation. Another option is to use a sample piece polishing tool equipped with polishing devices, dust exhaust tube, cooling devices, and a speed regulating device for high efficiency and environmental friendliness. Additionally, optimizing the inspection process of the sample can be achieved by using a sample retainer with an aluminum layer and electrode to minimize electron beam dispersion and obtain excellent SEM images. By incorporating these techniques and tools, one can effectively create sample plyers with precision and quality.
What is the fabrication procedure for parallel bars in physiotherapy?
5 answers
The fabrication procedure for parallel bars in physiotherapy involves innovative designs to address various needs. One approach includes utilizing a Flexible Parallel Bar with a control unit for adjustable height. Another method incorporates a portable parallel walking bar assembly made of lightweight parts that are easily assembled and disassembled for convenient transport and storage. Additionally, the use of Pneumatic Artificial Muscles (PAMs) in fabricating parallel bars allows for natural contraction upon inflation, offering a different actuation method for rehabilitation devices. Furthermore, the invention of rehabilitation parallel bars with adjustable heights, manipulating mechanisms, and linkage mechanisms ensures convenient and stable adjustments while maintaining the parallel alignment of holding rods. These diverse fabrication procedures cater to the specific requirements of physiotherapy patients, enhancing the effectiveness and accessibility of rehabilitation equipment.
What are the benefits of goat hair for sensitive skin?
8 answers
Goat hair, particularly from breeds kept for fiber production like Cashmere goats, is known for its unique structure, consisting mainly of non-medullated fibers that lack crimp, which contributes to its softness and gentleness on the skin. This characteristic makes goat hair especially beneficial for individuals with sensitive skin, a condition that affects many people worldwide and is characterized by unpleasant sensations in response to stimuli that should not normally provoke such sensations. The soft and gentle nature of goat hair can help in reducing irritation and discomfort associated with sensitive skin. Moreover, the application of goat hair in products designed for sensitive skin, such as brushes or textiles, can be seen as a natural and gentle alternative to synthetic materials that may exacerbate skin sensitivity. The utility model of a goat hair brush, for instance, emphasizes the importance of minimizing pollution to the human body and the environment, which is crucial for individuals with sensitive skin prone to reactions from chemical irritants. Sensitive skin's complex nature, involving reactions to environmental factors, cosmetics, and possibly underlying dermatoses, necessitates solutions that respect the skin's integrity and minimize potential triggers. Goat hair's natural properties align with the therapeutic approaches that aim to soothe and protect sensitive skin without causing additional stress or reactions. Furthermore, the development of sensitive skin solutions, whether through pharmaceutical compositionsor innovative sensitive skin devices, highlights the ongoing research and interest in addressing this condition. The use of natural fibers like goat hair complements these efforts by providing a gentle, non-irritating option for personal care and textile products, thereby supporting the overall management of sensitive skin. In summary, goat hair offers a natural, gentle alternative for individuals with sensitive skin, helping to reduce irritation and discomfort through its unique structural properties, while aligning with environmentally friendly and health-conscious approaches to skin care and textile production.
What is the significance of educational toy in middle school?
5 answers
Educational toys play a crucial role in middle school education by enhancing students' self-efficacy, understanding of engineering design processes, and scientific creativity. These toys provide hands-on experiences that traditional classrooms often lack, preparing students to solve real-world problems and fostering interest in STEM subjects from an early age. By engaging in toy design workshops based on the engineering design process, students not only improve their self-efficacy beliefs but also develop key skills like creativity and scientific inquiry. Additionally, educational toys promote learning interest, enhance concentration, and improve hand-eye coordination, making teaching easier and more effective. Overall, educational toys in middle school serve as valuable tools for promoting holistic learning experiences and nurturing essential skills for future success.
What are the benefits of using goat's hair for hair brushes?
10 answers
Goat's hair is renowned for its superior quality, particularly the Yangtze River Delta White Goat breed, which is the only breed known to produce high-quality brush hair, or type III hair, specialized for top-grade writing brushes. This distinction is attributed to the differential expression of genes in the skin tissues of goats, influencing the proliferation and apoptosis of hair follicle stem cells, thereby affecting hair quality traits such as the superior-quality brush hair produced by this breed. The unique properties of goat's hair make it an ideal material for various types of brushes, including cosmetic and writing brushes. For instance, a blended cosmetic brush head can simulate the natural feel of goat hair, offering a blend of fibers with varying diameters to achieve a desired softness and application precision. Similarly, the manufacturing method of a large goat hair bucket writing brush emphasizes the meticulous preparation and assembly of goat hair to achieve a high-quality writing instrument. Moreover, the utility of goat's hair extends beyond its application in brush making to innovations in brush design for enhanced functionality. For example, a portable goat hair brush with a self-cleaning function has been developed, showcasing the adaptability of goat's hair in creating user-friendly tools that save time and labor. Additionally, goat hair brushes have been designed with environmental and health considerations in mind, such as a brush that prevents pollution to the human body and the environment by collecting dripping paint. In the realm of animal husbandry and care, goat hair is also utilized in devices aimed at improving the health and hygiene of goats themselves, such as medicated bath devices and hair trimming means, which further underscore the versatility and benefits of goat's hair. These applications highlight the multifaceted benefits of using goat's hair, ranging from its superior quality for brush making to its utility in innovative designs and animal care practices.
What are the potential benefits of hair brushing for baby's hair health and development?
5 answers
Hair brushing for babies can offer various benefits for their hair health and development. A specialized baby hair wash and shower brush can provide a dual-purpose function by cleaning the baby's scalp with brush hair while also aiding in overall cleanliness during bath time. Additionally, a hair brush with a dual-shaped head can effectively manage both baby and mature hair, offering grooming and styling capabilities with different bristle types and a rotatable base for versatile use. Furthermore, a toothbrush designed for infants includes a buffer part to reduce the risk of throat thrusting accidents by buffering impact force, ensuring safety during oral care routines. Moreover, a hair growth therapy device resembling a hairbrush can stimulate hair follicles with multiple optical sources and vibration capabilities, promoting healthy hair growth and scalp blood flow.
What are the potential academic and behavioral effects of using a clock in the classroom for students?
5 answers
Integrating clocks in classrooms can have significant academic and behavioral impacts on students. Clocks designed specifically for teaching aids can enhance teaching efficiency by aiding quick clock identification, improving structure simplicity, and increasing student engagement. Moreover, multifunctional alarm clock systems in classrooms can prevent distractions, display schedule information effectively, and facilitate automatic management, benefiting students, teachers, and supervisors. Additionally, using clocks with interactive elements like small bells can further engage students by providing auditory and visual stimuli, enhancing learning experiences and potentially improving behavior in the classroom. Overall, incorporating clocks in educational settings not only aids in time management but also contributes to a conducive learning environment that promotes academic focus and student participation.