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Ergonomics in the Shop

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  • Ergonomics in the Shop

    I'm doing a research project on ergonomics and how they are implemented in a shop. If anyone has anyone ideas or answers to the questions, they would be greatly appreciated.

    Why are shop tables often covered in a thick clear coating?

    Why do some tables have evenly spaced holes in them?

    Why are working table tops at a lower height than machine table tops?

    Why are you forced to bend over when using certain power machines? (band saw)

    Thank you to anyone for any help they provide.

  • #2
    Thick clear coating on tables - to keep surface from warping or getting wet since wood is very pourous.

    Tables having evenly spaced holes. They're called bench dog holes. They are used along with clamps to hold workpiece in place for planing / sanding / other woodworking. There are different clamps you can put in these holes. Also You can put a peg in one of the holes and clamp it to table with and end vise. That's why they're evenly spaced to give you varying lenghts of vices you can create.

    As fo r the rest, I don't know. Ergonomics. Aren't those in LEXUS's

    Hope this helps



    • #3
      Whare is Davederg when you need him, he is an Ergonmics consultant and always here.


      • #4
        First----welcome to the forum.

        Hope I can help----I do ergonomics consulting work.

        Your first two questions don't have much to do with ergonomics (fitting the task to the worker). A slick top "may" make moving items around with less friction, but it would help to know the application---other applications might require a non-slip surface.

        Why are working table tops at a lower height than machine table tops?

        The key height in a workshop is the person's standing elbow height (measured with the forearm at 90 degrees to the upper arm, then between the elbow and floor). With this goal, work surfaces should be at different heights, depending on the amount of physical force to be exerted. For example, a workbench, where you are going to be planing wood should be at a height 3-5" below standing elbow height since the hand positions holding a plane exert the best force and the least fatigue slightly below standing elbow height. A drafting bench, on the other hand, is very high---since no physical exertion is required and the working height is easier at a higher level---sometimes even slightly above standing elbow height, since vision is also important in this operation. Machines are generally mounted higher since the point of operation (where the workers hands are) should be around the standing elbow height-----you have more control of controls requiring fine adjustment and you get less fatigued compared to having to constantly reach up or bend over.

        Why are you forced to bend over when using certain power machines? (band saw)

        The relative height of a machine vs. the operator all depends on each one's height. On my bandsaw, the table is slightly above my standing elbow height---not ideal for me, but for long periods of work, I will use a short platform to stand on, raising my standing height. There is nothing more backbreaking than to stand hunched over a machine. Don't ask me why, but some manufacturers insist on making their tools shorter than anyone else. Thankfully, in most cases, this can be changed by adding a platform or mobile base (of course subject to not making the tool unstable).

        Bonus info. Even the ideal height of a tool can still be fatiguing after a long day----on some tools, having a stool or chair to sit in while working, is ideal to releaving back and leg fatigue----the stool should place your sitting elbow height at about the same as it is while standing----great for scroll saw work.

        BTW---fatigue is just the first sign of possible future cumulative injury, like carpal tunnel syndrome.
        Hope this helps.


        • #5
          Originally posted by daveferg:
          First----welcome to the forum.

          BTW---fatigue is just the first sign of possible future cumulative injury, like carpal tunnel syndrome.
          Hope this helps.
          Or in the case of some here also - diabetic neuropathy, similar to CTS but different in that it's actually the nerves that are dying and something that cannot be remedied by surgical procedure.
          Funny more are not aware of this too - considering about half of this country is in fact type II or the so-called X factor diabetic. Not a nice thought.
          It's hard to not know where feet are, even harder to lose the feeling in hands and fingers. One really has to pay attention visually at all times to what they are doing.


          • #6
            Why is there a thick clear coating on the bench top? Typically, a Good Bench top is very expensive and well made. It's to protect it from damage and other finishes. It's easily reserfaced with out getting into the wood itself, and refinishing when needed.

            Evenly spaced holes: Dogs, correct. The travel of the vise determines this spacing. No matter the size of stock in which you wish to clamp, you can position a dog in one of the holes, and one in the vise's outer jaw, and clamp firmly onto it to stabilize it to work on it.

            Why is work tables lower than machines? When using machines, your are typically working with a single component of a project, a single piece of wood. Dave's ergonimics are very precise. When you get to the Work Table stage, you are assembling or dealing with an assembly of multiple components. In gerneral, a larger, taller item. Putting it lower to the floor will give you greater working range. Also, for fine detail work, a normal chair is the proper height to sit compfortably at the work table for extended periods of time.

            Bending over to use a band saw? Unless you have mounted a small bench top band saw to a work table, I have never seen a band saw you have to bend over to use. Or, unless you are of basketball stature. Dave, here again, is correct in stating stabilizing yourself for the task at hand. Safety also plays a big factor here. You must not be off balance in working with razor sharp tools, or power tools.

            Everyone's perticular height range is different. My machines would be considered over heigth for my size. I have back problems, and is better all around for me to keep my back as perfectly verticle as possable. If I work for a few hours in a slight bent over position, I am in a state of discompfort. Causing loss of concintration which is a safety factor. I also loose stability, again, a safety factor.

            When it comes to power tools, or using razor sharp hand tools, you must be able to maintain concintration of the task, not let you mind drift to discomforts distracting you from the safety hazards.

            Just my pair of Lincoln Heads worth.
            John E. Adams<br /><a href=\"\" target=\"_blank\"></a>


            • #7
              Chipmaker and Woody---very good points!

              To add to what Chipmaker said----if you every do loose feeling in your hand/fingers---and it's more than a few times in a week----you should have it checked out. Other symptoms worth checking----pain directly related to an otherwise simple activity----numbness/tingling or pain radiating up the arm. As Chipmaker points out----it could be other factors---in the case of a cumulative injury---the faster you catch it, the quicker treatment can get you back to normal.

              For those interested----here's a list of body postures that indicate poor work positions:

              1) WASHER WOMAN-- Hand to wrist position that is like the action of wringing out a wash rag. Deflection, flexion, etc.

              2) BIRD WINGS-- Work position where the elbows are forced out, away from the body. Causes pronation; ulna and radius crossing, which can cause elbow problems.

              3) HALF SHRUG--Work where one shoulder is above or below the other. Places undue pressure on shoulder and neck. Usual solution is to change the position of the worker or the work.

              4) REACH OUT-- Working outside the area of power/comfortable reach. A forty degree arc in front of the standing or sitting position is considered the ideal. Reach should not require arm extension of more than 120 to 130 degrees from the centerline.

              5) POWER ZONE-- Work height of most power/comfort; mid-chest to mid-thigh.

              6) HEAD CASE-- moving head to poor position searching for visual target. Can lead to neck or other body trauma. Move person or work.

              7) BOTTOMS UP-- Relates to improper lifting or bending, causing posterior to be high point of body. Again, move the work or the person.

              8) SOO FAR AWAY-- Keeping a lift or work close to the body. The further the weight or work is away from the body, the higher the weight or stress. Arms- the greater the extension angle, the greater the stress.

              9) THE TWIST IS DEAD-- Don't twist and lift. Also, don't twist and do work which may put strain on trunk or back (see number 4).

              10) SIT-STAND-- Tasks that could be accomplished better by converting the work station into a Sit-Stand configuration.

              11) GRIDLOCK-- Static work for prolonged periods can cause CTD's and/or muscle atrophy. Need to vary job tasks to add movement to routine.

              12) GOOD VIBRATIONS; NOT!--A vibrating tool or work area can lead to circulation problems or degeneration of tissue (back disks). Eliminate or dampen the problem.


              • #8
                dave dave dave what do you mean no effort is needed at the drafting table, that s the most frustrating part of the job bill


                • #9
                  Wow...thanks everyone. I never thought I would receive that much help. I greatly appreciate it.


                  • #10
                    Bill---no effort at drafting table?-----

                    But, now that I think of it----how many drafting tables even get used anymore. Is it like vinyl records? [img]tongue.gif[/img]