Ahh, this exactly the type of informed repartee I was looking for; and what a surprise as to the source :) comments below... Jude Reveley, RPT Absolute Piano Restoration, LLC Lowell, Massachusetts (978) 323-4545 ----- Original Message ----- From: "Ron Nossaman" <rnossaman at cox.net> To: "Pianotech List" <pianotech at ptg.org> Sent: Friday, October 05, 2007 12:50 AM Subject: Re: Introducing the Crownulator > >> For all you folks that have already made your Farell/Wixey/Lowell >> dowmbearing guages and are wondering what to do with your old bubble >> guages, I introduce.. >> >> "The Crownulator" (patent pending)...:) > > Hi Jude, > A couple of things. A counterclockwise indicator would be > nice. Would a digital indicator, zeroed at dead flat, read > negative so you wouldn't have to subtract from 0.75? Or are > there digitals switchable to "backward"? Indeed. This indicator is, as I hinted, recycled from my downbearing bubble guage that I bought from Pianotek for $60 many moons ago. > > Next is, a compression ridge or two will give you a false > positive crown reading on a flat or even concave board. Spacer > feet at the ends of the bar would avoid that. Nice. I knew this would be the prototype. The new and improved version will be the cRONulator 5000. > > Then there's the "S" curve crown, which can easily read > positive within the right 12" span. My hope is that this tool will yield more reliable data in the study of Pressure and Sag as it relates to scaling, soundboard and rib design etc. I've thought about compression ridges, "S" curves and all the other "anomolies" that depart from our ideal of crown and how that might affect the data. Ideally, I would love to set up some sort of laser grid that would automatically supply me with a 3D model on my computer. I've put a few calls into NASA, but I'm still waiting. In the meantime, I imagine there will be some learning curve as to the best way to use the crownulator, to avoid the pitfalls or at least get an improved look at what's going on under there; but I'm sure it beats my ratty piece of twine that the cat keeps dragging out of my tool bag. Specifically, before and after results of the board ribbed with no bridges, then with bridges, then installed, then loaded should be interesting. Time will tell, right? Also Dale brings up the fact that crown on a loaded board is often imperceptible when there may actually be .010" over 12", for example. I've tried loading punchings and holding a ruler under my twine to get a better measurement, but I keep getting a cramp in sixth arm. BAAAAH! Problem solved. I would also like to humbly suggest that we upgrade the way we describe crown. I've heard too many descriptions of crown as an arc deflection without any relation to a span, specifically as it concerns setting static downbearing, which just seems incomplete. > > But who checks crown anyway, eh? <G> Why the crown elves, of course, that come into the shop in the wee hours. Don't you have them in Kansas? > > Ron N > > -------------- next part -------------- An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20071005/06caa60b/attachment.html
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