Re: [Harp-L] widening out/opening up the backs of harps

[Rick Dempster <rickdempster33@xxxxxxxxx>]

I have carried a harp in my trouser/jeans hip pocket, daily, for forty-five
years, Michelle.
Just relaying my experience.
But to continue from your theoretical point of view, once that right-angle
flange has a kink in it,
it's all rapidly downhill. Guess I should do a 'control' experiment, if we
keep up the
discussion. I'll let you know when I build up the energy!
Cheers,
RD


On 10 March 2016 at 02:11, Michelle LeFree <mlefree@xxxxxxxxxxxxxxxxxxxxx>
wrote:

> Rick Dempster wrote:
>
> I agree, no difference worth noticing; but what, for example, Joe Spiers
>> does makes the plates stronger,
>> so my 'pocket' harp does much better with this particular mod.
>> RD
>>
>
> I have to disagree here, Rick. stock SP20 cover plates are significantly
> stronger than "opened" plates for two reasons.
>
> First, from a vector mechanics (physics) viewpoint, the vertical component
> of the right angle flange at the back of  the harp contains a lot more
> metal to resist vertical downward force (or upward on the bottom plate)
> than opened plates do. This is the same concept that engineers apply in
> their use of structural I beams.
>
> That vertical part of stock cover plates also contain struts that help
> stabilize the cover plates. When you open the back you flatten those struts
> out.
>
> The comb's plastic struts support the center of the cover plates but the
> other two mechanisms for resisting downward forces are gone when you
> flatten those vertical flanges.
>
> But, it does look cool. 8^)
>
> Michelle
>
>
>