Re: [Harp-L] Carbon Fiber Reeds, 3D printing, plastic metal adhesion technology...?

[Joseph Leone <3n037@xxxxxxxxxxx>]

On Feb 20, 2013, at 3:43 PM, Vern wrote:

> 
> On Feb 20, 2013, at 12:06 PM, John Ingham wrote:
> 
>> What can you tell me about the possibility of carbon fiber reeds,
>> products, experimentation. Is that just a crazy notion?
>> 
> 
> Carbon fiber has a very high strength-to-weight ratio making it ideal for many vehicle applications, particularly aircraft.  It has another desirable property in that the epoxy matrix absorbs vibrational energy.  However, these properties may make it less desirable for reeds which act as springs.  To my knowledge, carbon-fiber composite is not used for springs.
> 
> In reeds, you want a material that stores, not absorbs vibrational energy.  The pitch of a reed is determined by the square root of (k/m) where k is the "springiness" of the reed near the rivet where it bends and m is the weight near the tip that deflects.  You would probably have to attach a weight near the tip of a carbon reed to achieve the customary pitch-length relationship.
> 
> IF it were not for rust, spring steel would be the ideal material.  If you want to experiment, maybe a thin, protective coating could be developed.  Manufacturing spring steel and tuning would be problems to be solved.  The material that makes the best spring makes the best reed!
> 
> Vern  


Three things I can think of.
1...There WERE springs made of carbon fibre. They were on the Chevy II from the early 60s. They didn't work too well. Apparently when you put a hole in it (somewhere?), spider fractures start. I see a carbon fibre reed needing to be GLUED. Screws or rivets would qualify as holes..and that would be NON good. :(

2...In several America's cup yacht races, carbon fibre parts failed (masts, booms, spinnaker poles, block cheeks), causing the LEAD boats to loose their heats, and ultimately the cup. A sad state of  affairs for millions and millions invested...for naught. :(

3...Steel CAN be used for reeds. I have done it. First used a Gillette super blue blade, then a Schick copper clad. Finally a Wilkinson sword stainless. The steel reeds were ok as long as you
opened the harp from time to time and rubbed candle wax on the edges. (The flat surfaces were already coated). And I like the idea of a protective coating. :)

4...Ooooh, I just thought of another. Carbon fishing poles ARE springs. They also suck. Real good if you want a light rod and a sporting good time. BUT when they fracture, they virtually BLOW apart.
I have at least 16 rods in my bedroom closet which I have found in the marina dumpsters and re-built, They are ALL fiberglass. ALL the discarded carbon rods were junk. Un salvageable. :(

I agree with Vern that carbon fibre presents many challenges. Me? I would give it a shot. Sort of a Mt. Kilimanjaro to conquer. :)

smo-joe