Does anyone know whether Erich Sandner’s patent (1973 at http://www.flutopedia.com/patents.htm) is in the public domain already?
Francois.
This would seem to suggest it’s way over:
How long does patent protection last?
For applications filed on or after June 8, 1995, utility and plant patents are granted for a term which begins with the date of the grant and usually ends 20 years from the date you first applied for the patent subject to the payment of appropriate maintenance fees. Design patents last 14 years from the date you are granted the patent. No maintenance fees are required for design patents.
Note: Patents in force on June 8, 1995 and patents issued thereafter on applications filed prior to June 8, 1995 automatically have a term that is the greater of the twenty year term discussed above or seventeen years from the patent grant.
Terry
Thank you for your help.
I interpet that section in the same way.
My concern is that I see that, if you google “Sandner klappenlose flote,” one finds quite a few German manufacturers who are using Sandner’s patent. This makes me wonder whether the copy right might have been renewed.
Here’s my attempt at recreating Sandner’s idea to improve octave tuning. Can visit my website, “Modern Ethnic Flutes,” to see pictures: https://sites.google.com/site/modernethnicflutes/concert-flute-in-c
Hi!
I know Sandner’s spike device for octave tuning, I have used it successfully in some of my bamboo flutes, both diatonic and pentatonic. But…(there’s a “but”): the tone results muffled in some way (obviously, this might be a question of opinion), just as if one was singing but had something down his/her throat.
It also exposes the stopper/spike element to leaking problems (which of course you can take care of by using bees-wax, but then the spike remains fixed in one position only).
All in all, I think Sandner’s idea may be worth trying for the amateur flute-maker as a step towards more complicated yet promising matters.
Happy tootin’
Ro.
Fascinating link. One thing that struck me was the Strathmann adjustable block patent for duct flutes, which expires (according to the above) next year. So far it’s only been used on a couple of (very expensive) recorder models I’m aware of, but it could be a great option for low whistles.
Concerning Sandner’s patent, I had the same experience, i.e. that the sound appeared almost muffled in the beginning.
I experimented a bit more and have made a flute which has a spike device permanently mounted, i.e. it is not movable the way that Sandner’s patent drawings suggest. I basically make a flute stopper with a plug extending from it; after that I insert the stopper until my tuner tells me that I am playing a perfect C. After that I play a piece from Handel’s Messiah which contain quite a few octave jumps; I cut the plug to size until I am able to make all the octave jumps fairly effortlessly.
Despite the fact that Fajardo’s patent seems a lot more simple, I have had little success with it.
Any idea for octave tuning that you have found useful and practical?
Yeah: tapering the bore 