[Archers] More on PVC Bows

Tue Oct 9 12:07:11 PDT 2012

Having listened to the diatribe about PVC bows for a while now I thought I  
would add my knowledge of PVC and what worries me about this material.  It  
is not really a resilient material like fiberglass feinforced plastics such  
as polyester, vinylester or epoxy.  It is not meant to be flexed back and  
forth thousands of times and WILL de elop stress cracks along the tension  
surface.  This becomes MUCH more pronounced as the temprature of the  
material drops.  At around freezing it is so brittle hitting a piece with a  
hammer can shatter it.  With no reinforcing filament in its structure it  
erupts with considerable energy.  I would love to fool with one but would  
wear goggles and a face shield when doing so.  There seems like there would  
me many other materials more suitable and in fact I have tried Delrin with  
some success.  Unfortunately all the materials that would be suitable are  
not dirt cheap like Poly Vinyl Chloride.  Another problem with PVC is that  
every solvent on earth hurts it, and some will melt it right down.  Not even  
windex or other such cleaners are a good idea.  Last problem is UV light.   
It breaks down the molecular structure of PVCAt an incredible rate.  2 years  
in the sun and its done.  You could paint it but most paints that would work  
are solvent based and would damage the material.  Having explored tnis  
material further I have discovered fiberglass filled PVC which might be a  
viable alternative and would be more resilient and not so exciting when it  
fails.  All this having been said I have made and blown up dozens of bows  
and love doing it and will continue to do so.  If you choose to work with  
PVC..........use caution.

Sent from my Verizon Wireless Droid

-----Original message-----
From: Garth Groff <ggg9y at virginia.edu>
To: archers at seahorse.atlantia.sca.org
Sent: Tue, Oct 9, 2012 18:19:48 GMT+00:00
Subject: Re: [Archers] More on PVC Bows

M'Lord Christoph,

Yes, and as you point out, that sort of damage can be invisible. It might be  
possible that leaving it in the back window of a car for a few days would be  
enough to stress the bow to the breaking point when drawn even if it is  
wrapped. I have a little fiberglass camp bow in my dead bow collection that  
is twisted like a licorice whip, I suspect from cooking in a hot car.

OTOH, a bow that is wrapped could have a stress crack we can't see during  
inspection. At least a wrapped bow isn't likely to spread shrapnel around if  
it breaks.

Yours Aye,

Mungo

On 10/9/2012 2:13 PM, John Atkins wrote:
> As usual, Siegfried has an excellent point here.  My only concern about
> the PVC bows is the effect sunlight has on PVC.  PVC pipes left in the
> sun for a year or more become quite brittle.  When used to transport
> water even under the pressure for which the pipe is rated, it has no
> problems.  But step on it and it will shatter.  Thus a bow, which gets
> flexed in a manner never intended for the product may fail in similar
> manner.  There really is no way to check PVC for sunlight exposure.  It
> doesn't get darker or leave any tell tail indicators.  If PVC bows had
> limb coverings much like "horse bows" that would control the "flying
> pieces" during/if failure.  It would also prevent the sun damage to the
> material.
>
> 5 years running the Marine Aquaculture laboratory for San Deigo State
> University made me VERY familiar with PVC piping.
>
> cog
>
> -----Original Message-----
> From: archers-bounces at seahorse.atlantia.sca.org
> [mailto:archers-bounces at seahorse.atlantia.sca.org] On Behalf Of
> Siegfried
> Sent: Tuesday, October 09, 2012 1:06 PM
> To: archers at seahorse.atlantia.sca.org
> Subject: Re: [Archers] More on PVC Bows
>
>
>> However, a new bowyer is another matter. How do we judge his or her
>> experience? How many bows have they built? How long have their bows
>> been in use? Have any failed? Is this a new bow, or one that has had
>> say 100 shots from it (that's roughly four royal rounds, barely broken
>> in)?
> But that's no different than a wooden bow.  Is this someone's first
> wooden bow?  Or first attempt at a laminated bow?
>
> Or is this even the case of "Archer X drawing selfbow Y for the first
> time, and bow Y was tested at a 22" draw length, and Archer X draws at a
> 30" draw length ... and ... BOOM"
>
> I've seen those on the range, and I've seen them fail AMAZINGLY
> catastrophically, with chunks flying.
>
> And we have similarly no way to really inspect a '1st time bowyers' bow
> any differently, as it will look perfectly the same as an experienced
> hand.
>
> Siegfried
>
>

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