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About DMartin

  • Birthday 04/07/1943

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    Eliot Maine

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  1. The missing fundamental seems to occur in bass singers. Many predecessor instruments such as theorbo and rebec have long strings on small bodies which suggests missing fundamentals. My impression (subject to evidence) is that the violin family and modern guitars exhibit much stronger "breathing" resonances than all previous "string on box" instruments.
  2. Yes, lack of pretense. I was face to face only briefly, but he was very supportive of my experiments with balsa. Thought of wings is comforting.
  3. In this case, being impatient, I just eyeballed it as I wasn't planning to make one. The channel does rise through the C-bout though.
  4. In case anyone is wondering, here is a rigorous application of curtate cycloids to a possible top plate. I wanted to see for myself the flow of cycloids along an entire plate. As the cross-arch flattens, the inflection point (green and red lines) approaches half the width. The cycloids and blue surface were drawn by the visual programing package of Rhinocerous Cad as was the parametric center arch with curvature comb. The rough-stage edgework was traced from the Strad poster of the Plowden.
  5. Yes, though simple timber construction cannot withstand the resulting loads. Set screws allow fingerboard pitch and roll to be adjusted without removing strings. Yes — the fingerboard alone is the neck.
  6. The best playing of my experiments all have arched garlands, sometimes both front and back and to both end blocks. It is, at the least, an intriguing variable.
  7. Great to meet a fellow traveler in Rhino Land. I have spent the last 4 months transitioning to Rhino from several other Cad Aps that have become too expensive to maintain in retirement. Judging from your website, I interpret that you also find that exploring violin geometry with cad can clarify complex issues. In what language did you program your cycloid? To show that Rhino can indeed draw a smooth cycloid, here's a screen shot of my implementation of a curtate cycloid in Rhino’s Grasshopper Language (red points). The program also draws an interpolated or through-points spline (green). This is a somewhat back-handed procedure as first the small number of discreet points are calculated from a continuous function and then a nurbs curve is fit to those points by a separate hidden algorithm. The vertical red lines mark the high and low points of the cycloid as well as the inflection points which were calculated separately from the curvature graph function but show good agreement. In this image, the cycloid rolls through the right-hand endpoint on its way to infinity. The starting point on the left has been constrained to horizontal. My primary interest was to explore the behavior of the curtate cycloid and inflection points near the plate ends as the center arch varied from bulbous to slack. One instance, a little bulbous, is shown in the second image. This program version takes widths from a traced outline of the Plowden and heights from a variable nurbs center arch curve—similar in conception to your cross sections. Just to show off, 100 cycloid sections are shown. Parameters are varied by numerical sliders.
  8. It’s been some 30 years since I last purfled. A few weeks ago, taking on the challenge yet again, l messed around in quick and dirty mode to work out these “bench slider" concepts. Thought they would fit this thread as they worked well for me. They allow a low grip. The aluminum snap-on ring of the cutter/marker tool has a region filed to the thickness of the purfling to enable quick switching between inner and outer cut while using a single blade. The picker blade shown in the 5th photo can be mounted in place of the cutter to scrape the bottom of the purfling channel. The scratch stock helped establish the edge channel. Right thumb grips in place of the purple clamp. I found it easiest to set the cutting depths with the calibrated wedge technique.
  9. Don, I like your thread title. Coincidently, I have spent the better part of the last ten days messing with cycloids. I’m in the final stage of arching a Plowden derivative, while also in the process of shifting over to Rhino cad. Wondering how my arching compared to curtate cycloids, I took a stab at implementing cycloids in Rhino’s visual scripting language, Grasshopper. First I made a unit circle version with a mouse slider to move the virtual pencil point any where along the generating radius. The output also drew a curvature comb. Playing with this toy proved useful to me. Then I changed the input to accept typed dimensions with a properly-scaled output. As an exercise, I traced c-bout curves from Michael Darnton’s laser stripe photos published in The Pegbox and output matching cycloids. The comparison is show below. I share your interest in the longitudinal flow of surface curvature. The first thing I did with the first cycloid templates was to plot the curve of inflections on my Plowden back. Because I used the purfling as a convenient width reference, there is a cusp at the corners. I’m interested in that because I think I see traces of such a cusp showing in some photo’s and videos of master instruments. I don’t plan to follow the templates slavishly. Rather they may play a role in my internal dialogue. The cycloids could give a concrete, repeatable-anywhere, surface definition for a base reference. I can foresee a mental model such as, “right around here I like to run 2mm over the cycloid” definition while here I tend to scrimp a bit. Well I see the thread has progressed while I struggled with the computer.
  10. I fully agree with your 30 second assessment. The hot air systems I encounter are very harsh. If you (or a violin) are near a vent your are periodically breathing air that is drier than the room average. To say nothing of accumulated dust and mold in old systems. I'm probably not alone in finding the best systems are broad–area radiant. My partner downstairs keeps her studio air temp just above 60°F and it's very pleasant — radiant concrete floor. I have a hot-water baseboard which distributes mostly by convection as it is small in area and shadowed from direct radiation on my body. Short of installing broad radiators in the walls, floor or ceiling, I'm imagining that an eight foot black stovepipe hanging near the room center and heated to 80° to 90° would allow me to drop the air temperature another 5°F.
  11. In the hands of this duo on this recording this Strad talks to me of Beethoven: Beethoven Sonata #10 — Perez/Dumay I give equal credit to the pianist and assume (hope) the fiddle is the Harte once played by Francescatti, the only great player of the 1950's that I heard in person.
  12. Thank your posting your first and bringing fond memories. I had recently noticed that the outline drawing included with "You can make a Stradivarius" is very close to the 1721 Kruse in the Strad Mag poster. Reid's drawings and arch patterns do not show FF fluting. Don't know if the text mentions that as the book itself wandered off years ago. On the other hand, in 1957, the book enabled a thirteen-year-old to start making without a mentor. In addition to drawings of all the necessary tools, it also cited tonewood and fitting sources Rembert Wurlitzer and William Lewis and Sons. I eventually visited Wurlitzer in 1960 and was invited to walk through the long narrow workroom with its single bench. The only worker that talked, a dark-haired fellow, handed me the luscious white violin hanging above his work area. Believe he was René Morel.
  13. Yes, the ff reminds one of the Messiah. What a shame.
  14. Seems to be a gift — distinctively sensuous. Someone will come to love it.
  15. If you click the arrow, one of the photos shows the setter with an S-bend. Not in use though.
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