David, the clamps are about 4" long, rubbery coating on the part that clamps.  Yes, the clamps require a serious force to open.  My wife cannot do it with her somewhat arthritic hands, though I have no trouble.  However, a strong wind?  Hmmmm........... .   The assembly is simply the end of the tarp folded into a sleeve and sewn, with a piece of pvc electrical conduit slipped through.  The sleeve with the conduit is laid into the gutter, and four of these clamps applied.  I have not had a collapse yet due to wind, including in the Rockies.  mcneely

---- David Beierl <dbeierl@attglobal.net> wrote:
> At 04:05 PM 7/17/2011, Dave Mcneely wrote:
> >for my jury rigged (but good) home design awning, I use carpenter's
> >clamps, spring loaded.  Work great.  mcneely
>
> How do they work in a strong wind?  Are you talking about metal
> clamps around 4" long that take a serious effort to open?  I've
> always been concerned that any kind of spring clamp would release in
> a strong wind...
>
> Yours,
> David
>

--
David McNeely