Design Help Request

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Phil S

Phil Soper
Corporate Member
DQ
I have agreed to outfit our Outreach lathes with spectator shields. I will be fabricating these shields out of polycarbonate sheeting like Lexan. Size will be 30" high and 36 wide, but I am not sure how thick the plastic needs to be. I tend to lean to the when in doubt, make it stout theory but thicker gets costly. Any expert help on this would be nice. Thanks in advance
 

Mike Davis

Board of Directors, President
Mike
Corporate Member
DQ
Agree, we used to make sign faces with Lexan, 1/4 inch was standard for 4x6 foot electric signs. Anything smaller would get 1/8.
 

ehpoole

Ethan
Corporate Member
DQ
A lot will depend upon how the Lexan is supported. If it is rigidly mounted on al four sides then I would be pretty comfortable with 1/8” as well unless you will be turning very large off-center/balance pieces, n which case I would go with 1/4”. If not well supported on all four sides then I would go with 1/4” to be safe. If the Lexan will only be supported by a rabetted edge and not through bolted then you will want a large overlap area as Lexan can bend tremendously if impacted hard — ideally you will want a large overlap area and through booting around the edges. That tendency to bend, and even distort, on severe impact rather than shatter or snap, like acrylic, is part of what gives Lexan its extreme strength, it is very hard to actually pierce or otherwise “break” through Lexan.

If you do go with 1/4” and you have any scraps left over that are at least 4”x4” to 5”x5” then I would be interested in possibly buying some of the scrap as I need to make a few guy rings for a 50ft temporary antenna mast. Assuming that this is to be done soone, otherwise I will probably go shopping for what I need over the next week or two.

When designing the rest of the shield you will want to build it fairly heavily out of either wood or steel and you will likely want to be able to stack some real mass (such as sand bags or 5 gallon buckets filled with water, on the lathe side of the shield to help the shield assembly absorb and deflect a severe impact. There is a good chance it may still get knocked over if hit especially hard with a very large piece, but that added mass will help it to absorb and dampen most of the force and deflect it before it falls so that it is only the weight of the shield itself falling into the audience. Legs extending out and into the audience side would greatly reduce the risk of it falling over.
 
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Phil S

Phil Soper
Corporate Member
DQ
I will not be making these until Jan. Ethan thanks for the input, it has me thinking as I need to make these portable and light while also being strong enough to serve the intended purpose. We only do small spindle turning.
I am now wondering if there is an official design spec we must adhere to.
 

Graywolf

Richard
Corporate Member
DQ
Phil, just a short web search I found no specifications and very few ideas. I have seen these shields employed at demos before, I think for what we do the 1/8" material will work with a full frame.
 

bowman

Neal
Staff member
Corporate Member
DQ
With the small items that are turned on these, I feel 1/8 will be sufficient.

At 30x36, how are you planning to secure these to the lathes?
 

Dee2

Gene
Corporate Member
DQ
AAW has guides/plans and videos. PM if you want the links. I meant to give you copies and forgot. Or send me a fax number. It may be Monday before and I can send a fax, however.

AAW plans call for 1/4" polycarbonate.
We may have a capstone project next semester for a design. I'll have the students develop launch trajectories, forces, etc. for a reasonable sized wooden missile. Or maybe a sensitivity analysis across a range of parameters. Testing should be fun. LOL.

Lawyers will want analysis or (AAW?) standards, not gut feel or experience.
 
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Jeff

Jeff
Corporate Member
DQ
AAW has guides/plans and videos. PM if you want the links. I meant to give you copies and forgot. Or send me a fax number. It may be Monday before and I can send a fax, however.

AAW plans call for 1/4" polycarbonate.
We may have a capstone project next semester for a design. I'll have the students develop launch trajectories, forces, etc. for a reasonable sized wooden missile. Or maybe a sensitivity analysis across a range of parameters. Testing should be fun. LOL.

Lawyers will want analysis or (AAW?) standards, not gut feel or experience.
I was curious so I went to the American Association of Woodturners (AAW) website and searched for lexan safety shields and lathes, etc. No hits despite several iterations of the safety idea. I'm not an AAW member and maybe its member only content.
 
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Runk

Runk
Corporate Member
DQ
You might want to look at grinding wheel safety. Shields used to protect the user from a wheel that breaks in use which sends pieces in all directions. Shields have to protect against the impact of the flying projectile. Mass is taken into consideration when doing the calculation. NIOSH will have written standards for this since this is a work place hazard. When looking for safety standards on almost any hazard that could be work place related, NIOSH will have written a standard that has been tested.
 

Dee2

Gene
Corporate Member
DQ
Jeff, et al.,
Here are some links

Cheap version: https://cdn.ymaws.com/aaw.site-ym.com/resource/resmgr/BestPractices/LCSafety_060.pdf

Sophisticated - I think the TAW uses those - and materials cost about $800. It includes structures for mounting various cameras. Here's the link:
https://cdn.ymaws.com/www.woodturner.org/resource/resmgr/BestPractices/BP127SafetyShield.pdf
and the video
https://vimeo.com/72198125

Now a question for all of you, for marketing our presence at the AAW next year, please send me a quote about why NCWW is important to you.

Thank you
 

Jeff

Jeff
Corporate Member
DQ
Thanks Gene, I found your last 2 links earlier this morning and watched the assembly video. I imagine that Phil is interested in the cheap version and both use 1/4" Lexan.

Jeff, et al.,
Here are some links

Cheap version: https://cdn.ymaws.com/aaw.site-ym.com/resource/resmgr/BestPractices/LCSafety_060.pdf

Sophisticated - I think the TAW uses those - and materials cost about $800. It includes structures for mounting various cameras. Here's the link:
https://cdn.ymaws.com/www.woodturner.org/resource/resmgr/BestPractices/BP127SafetyShield.pdf
and the video
https://vimeo.com/72198125

Now a question for all of you, for marketing our presence at the AAW next year, please send me a quote about why NCWW is important to you.

Thank you
 

Jeff

Jeff
Corporate Member
DQ
I have agreed to outfit our Outreach lathes with spectator shields.
How long have the lathes been used at Outreach events without shields and what prompted this request? Aren't the Outreach demonstrations mainly small spindle turnings like the light sabers? Just curious.
 

KenOfCary

Board of Directors, Treasurer
Ken
Staff member
Corporate Member
DQ
How long have the lathes been used at Outreach events without shields and what prompted this request? Aren't the Outreach demonstrations mainly small spindle turnings like the light sabers? Just curious.
We are attending an AAW event as a demonstrator and they have standards that must be followed is what prompted this effort. And yes we only do small spindle turnings.

Answer to first question is since Outreach began.
 

Jeff

Jeff
Corporate Member
DQ
Thanks. Where and when is this AAW event?

We are attending an AAW event as a demonstrator and they have standards that must be followed is what prompted this effort. And yes we only do small spindle turnings.

Answer to first question is since Outreach began.
 

TENdriver

TENdriver
User
Phil, Just brainstorming, but is there be any advantage to making them smaller multi panels that fasten together?

You’d reduce the size of each Lexan panel required. That might lower the cost of replacing a small panel versus a larger sheet.

There could be additional frame structure around each sheet.

Panels would be smaller and easier to manage for handling and storage.



perhaps there are other advantages (or disadvantages) to a multi panel configuration.
 

Jeff

Jeff
Corporate Member
DQ
Ken said that NCWW will be demonstrating at an AAW event and they have standards that have to me met (I think it's in Raleigh, June or July 2019).

The AAW links that Dee2 provided describe Lexan safety shields that are 24" x 36" x 1/8" and Phil is suggesting 30" x 36" for our NCWW lathes. We may not have much leeway to play with the basic design.
 
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