Safety Article in AW

Discussion in 'Woodturning Health & Safety' started by Andy Chen, Dec 16, 2012.

  1. Andy Chen

    Andy Chen

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    I just received the December issue of American Woodturner this past week. Ed Brannon wrote an excellent article on safety (p 19). However, I was most disturbed by the accompanying photograph. Pascal Oudet is wearing a face shield during a demonstration at the 2010 AAW national symposium. Evidently, many woodturners do not realize there are many different kinds of face shields. We probably all know better than wearing a welder's face shield while turning wood, but do you know what kind of face shield Pascal was wearing? It is a splash shield that is designed for chemical splashes. It has a thin plastic shield that is not strong enough to protect from flying wood blocks. It also has an aluminum rim for stiffening the thin plastic. The problem is if the plastic shatters, the aluminum can be forced into your face which is exactly what happened to a couple of members of our club a number of years ago. The aluminum ended up in their cheeks causing severe lacerations and a trip to the ER. The correct type of face shields woodturners should be wearing is the thick polycarbonate shield without the metal rim. They are widely available (Sears for instance) for under $15.00. Be safe and happy turning
     

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  2. odie

    odie

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    Thanks for the "heads up".......I wasn't aware of the differences between a splash shield and a face shield. As it turns out, I've been using a standard face shield from Woodcraft for about a dozen years. Prior to that, I used over the glasses safety glasses and goggles.

    It makes sense that the metal rim of a thin splash shield could be a hazard.

    As I understand it, none of the face shields are designed for protection from "flying wood blocks" either. There really doesn't seem to be anything designed specifically for baseball sized blocks of wood coming at your face with the velocity a major league pitcher would throw it........

    So, what's the solution? Well, staying out of the line of fire is a great suggestion, but that limits your ability to see what you're doing, and to guide your lathe tool for the best cut. Staying out of the way is the best overall safety advice.....but, to be honest, many of us are going to fudge the guidelines for a quest in excellence at the lathe.

    For me, I've decided to take my chances, and do what is best for the best cut.......within certain boundaries. It's hard to say what those boundaries should be, but it's a sure thing that everyone will evaluate the hazards, risks, and necessary safety precautions differently.

    I nearly always use a face shield. Sometimes I use a combination of face shield and safety OTG safety glasses. When the "pucker factor" is great, I have a modified hockey helmet which I use with OTG safety glasses. When there are cracks, voids, bark inclusions, anything judged to be a weak spot, I use the hockey helmet.

    There are a few times where I use only my prescription glasses, sometimes in conjunction with a magnification visor. During these times, I almost never am in the line of fire, but I can't say never.......there is a calculated gamble every once in awhile.


    =============================================================



    I have a related question about the "bionic faceshield".......I've never used one, but to me, this looks like nothing more than a regular face shield with some surrounding plastic around the lens. Is this supposed to provide additional protection from impact, over the standard face shield?

    After looking up the term "bionic", I just don't see how the name applies.......must be some kind of advertising gimmick for sales to people who see the term and somehow think there is a magical application of the term to a perceived safety advantage......but, I see no such connection.

    ooc






    Below is a picture of my modified hockey helmet. I don't use it very often, but when I do, there is a definite subconscious safety alarm going off for me.........aka: the pucker factor! When this pic was taken, I had planned on adding a face shield to it, but the OTG safety glasses work here just as well......
     

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    Last edited: Dec 16, 2012
  3. Bob Chapman

    Bob Chapman

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    Thanks for that, Andy. I wasn't aware of the difference.

    Bob
     
  4. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I agree with you on the second part about using face shields with thick polycarbonate. However, per your other statement regarding flying wood blocks, there are no face shields that can provide that sort of protection. There is a simple reason -- there is no way for them to absorb the kinetic energy of a large impact. They are practically weightless a sit lightly like a hat on your head. Any sort of impact from a large piece of wood is most likely to knock the faceshield off the wearer's head, but not before transferring much of its kinetic energy to the wearer's face. The bad news is that most turners have a false sense of security regarding major impacts while wearing a face shield. A better approach is to use turning practices that minimize the risks and then wear a face shield along with goggles while keeping in mind that you need to still stay out of the way of things that might fly off the lathe. If something does fly off the lathe, spend some time thinking about what you could have done differently to avoid such a situation.

    Being complacent is one of our worst problems that can invite injury.
     
  5. Alan Lester

    Alan Lester

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    I purchased a face shield from Lee Valley, it has a rigid plastic frame around the lens but I'm not sure if it would stop a large object or just get pushed into my face by it :( .
    As a relatively new turner, 2 years, I'd like to make a general observation (no offence intended, I may be missing the BIG picture). Most people turn bowls on lathes primarily designed for spindle work. This tends to put you in the "line of fire" a good part of the time. When I decided I was going to get a bit more serious about turning I thought it would be nice to get a lathe designed more for bowls (I already had an old Rockwell spindle lathe). I bought a Vega 2600 which is designed primarily as a bowl lathe that will do (short) spindles. Perhaps because I more or less started on this lathe I find myself standing at the end most of the time and have a difficult time turning the inside of a bowl on a regular lathe.
    Alan
     
  6. charlie knighton

    charlie knighton

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    i have HEARD that if you turn at speeds less than 1000 rpm, that the flying object will go away from you, and if you turn at more than 1000 rpm the flying object will go towards you........

    can anyone refute or agreed with that statement

    most demostrators i have observed turn at speeds way faster than 1000 rpm
     
  7. john lucas

    john lucas

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    OK I'm not an engineer, scientist or anything like that. But there isn't any way rpm has anything to do with direction of a flying object. If the bowl explodes it's going to do so on any part of the revolution. RPM will have an affect on when or if a piece explodes.
     
  8. Bill Boehme

    Bill Boehme Administrator Staff Member

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    More importantly, did the person who said that to you offer any sort of rationale for something that appears to be counter intuitive? It doesn't take an engineer or scientist to call such a claim nonsense.

    Actually, I think that whoever you heard it from was making a tongue in cheek comment with a couple implied messages ... keep the speed down and watch where you're standing.
     
  9. john lucas

    john lucas

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    It was on the internet so it must be true. :)
     
  10. MichaelMouse

    MichaelMouse

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    One thing for sure is that turning at lower rpm imparts less energy to the errant piece. I can't remember last time I had the Nova above 680, but I'm a slicer, not a scraper. I also stand in front of the bowl turnings with the toolrest tight and willing to take one for me.

    Third law says the chunk you knock out with the tool is going to go opposite, unless it meets something else, which is first law.
     
  11. odie

    odie

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    Speed is irrelevant to whether your tool is cutting cleanly, or not. You are entitled to your opinion, MM........but, speed allows a turner (or, specifically.....me) to guide the tool with greater control of the cut, through an artistically appealing curve. By saying that, it is not to imply that you can't achieve equally appealing results by your methods, but speed is an essential benefit to mine.

    ooc
     
  12. billooms

    billooms

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    I was an engineer in my first career (prior to wood turning). I assure you that the direction of a flying piece has no relationship to rpm. At the moment it breaks loose, it continues in a straight line until something else slows or stops it. Double the rpm and you get double the velocity with 4X the energy.
     
  13. MichaelMouse

    MichaelMouse

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    There you go again, putting up straw men. Scraping, as I said, is not the same as slicing. It is a high friction option which demands greater energy to work properly. Those who might doubt have only to observe the difference as the chips/dust "fly" (third law) rather than simply slide down the slicing edge and drop. The higher angle also makes the work squirm and chatter if it's not done with the utmost care to remove the least material.

    Speed of tool feed and speed of rotation, when in balance, allow a slicer to make long shavings, which leave a surface as unbroken as themselves. You may remove a lot of wood rapidly, with a shaving either thick or wide, with little to no increase in resistance. Going both thick and wide (hogging) does resist a bit more, but not nearly as much as scraping. Win-win. Safety in slow, smooth in slice. Tough to pass up a deal like that. The continuous motion allows a fair curve with great ease, just as it does in carving or planing.

    Principles apply to all turning actions, regardless the individual's technique, which is why it's important to observe and analyze.
     
  14. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Newton's third law is about direction of forces and not direction of motion. The above statement oversimplifies the situation. In the real world, the "chunk" might travel in any direction.

    Another unrelated scenario for a "chunk" departing is "no visible means of support". Suppose that there is a hidden defect and that the turner is making clean slicing cuts. At some point the centrifugal force acting on that "chunk" will be greater than the reaction force of the ever-diminishing supporting structure that is holding it in place. Since the supporting structure does not yield instantaneously, the direction of travel is unpredictable.
     
  15. MichaelMouse

    MichaelMouse

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  16. Patrick Miller

    Patrick Miller

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    The REAL scientists..

    This is definitely a question for MYTHBUSTERS.
     
  17. AlanZ

    AlanZ

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    If you hit a stationary object from the south it usually but not necessarily goes north.

    It depends on the relative size and energy present in each object.

    I can slam into a brick wall all day, from pretty much any direction and it won't move much, if at all. I, on the other hand, will get beaten up pretty badly.

    As a motorcyclist, I've always called this the "Right of Weight"

    A large rotating blank, and a small anchored chisel... I could not easily predict if the chunk coming off will head for the ceiling or the floor before eventually coming to rest in some very inconvenient spot..
     
  18. Harry Robinette

    Harry Robinette

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    I went to the Uvex Bionic face shield web site and found this info.
    This shield is made for : Perfect Protection from Falling and FlyingObjects
    ANSI Z87.1-2003 High Impact Protection certified to the requirements of
    CSA Z94.3
    Polycarbonate construction
    It's not 100% protection but I use one of these because I fell it's better then a plane face shield. Also can't find anywhere on the 3m Airstream helmet that say's it has High Impact protection and thats the one you here about all the time for protection.
    Just my opinion and what I could find in writing.
     
  19. robo hippy

    robo hippy

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    The 1000 rpm rule is one I have heard mentioned by Stuart Batty. If you are going below 1000 rpm, the piece will bounce a bit but generally fall down. When you get above 1000 rpm, then things go 'airborn'.

    Slicing/scraping: this is a matter of cutting edge presentation to the wood, and not rpm. Scraping cut, scraper flat on the tool rest, or gouge edge at 90 degrees to the rotation of the wood. Slicing cut, scraper or gouges at 45 or more degrees to the rotation of the wood, often called shear cut or shear scrape. The difference between shear cut and shear scrape seems to be whether the bevel is rubbing (cut) or not (scrape).

    robo hippy
     
  20. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Harry, the polycarbonate shield on the Airstream has the required ANSI marking for impact protection, Z87.1+, where the plus sign indicates it meets the high velocity impact requirement. It should be noted, however, that what we woodturners consider high velocity impact is an entirely unrelated to the way that US ANSI Z87.1 and Canadian test requirement CSA Z94.3 define it. Basically, face shields are designed for eye and face protection from small high-speed flying particles as well as chemical splashes. The following summary shows the type of impact tests in the latest version of Z87.1.

    Impact Test Requirements as defined under ANSI Z87.1 - 2010

    • High Mass Impact -- Face shield shall be capable of resisting impact from a pointed projectile weighing 17.6 ounces dropped from a height of 50 inches.
    • High Velocity Impact -- Face shield shall be capable of resisting impact from a quarter-inch diameter steel ball traveling at a velocity of 300 feet per second. For sample size of 20, no failure may occur.
    • Drop-Ball Impact -- Basic impact requirement for all devices: 1 inch diameter steel ball weighing 2.4 ounces dropped from a height of 50 inches.
    • Penetration Test -- Face shield shall be capable of resisting penetration from a weighted projectile weighing 1.56 ounces dropped from a height of 50 inches.
    Woodturners generally think of face protection not only to include the small high speed particles, but also slower but much more massive "chunks" of wood. The latter, unfortunately can't be provided by a faceshield because there is no energy absorbing mechanism to speak of. Given that the faceshield is attached to the wearer's head, that becomes the primary energy absorber. Add to that the soft flexibility of the faceshield structure and it becomes apparent that the part of the head taking he brunt of the punishment from a serious impact is the face.

    The ANSI 2003 standard states that face shields are considered secondary eye protection and must be used in conjunction with safety glasses or goggles. The 2010 standard does not distinguish between primary and secondary eye protection. Most manufacturers of face shields suggest using safety glasses or goggles underneath face shields for additional eye protection.

    While the current ANSI standard for eye and face protection is Z87.1 - 2010, OSHA approves employers to use protective gear certified to prior standards if the same level of protection is provided for the intended application.

    Is it worth wearing a faceshield? Definitely, yes because most of the stuff that we encounter is small particles like shavings and chips and bark. Does a faceshield provide adequate protection for turning at the lathe? If we don't get hit by a large high speed "chunk", then yes; otherwise, no. Knowing that we are not invincible is worth something in prompting us to avoid doing dangerous and foolish things -- hopefully.
     
    Last edited: Dec 18, 2012

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