Oded Kishony

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About Oded Kishony

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    Central Virginia, USA

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  1. “it’s only a violin” I.e. not a sacred relic..... oded
  2. Yes, this wedge is used to level a 'step' in the plate. It's easier to visualize if you think of getting the two sides to first line up, using your fingers, then inserting the wedge, effectively making one leg a little longer than the other. It works, even if it doesn't seem obvious. The over sized hole is on the lower thumb screw, on the knurled side, to allow the towers to 'rack' a bit, otherwise they would always be perfectly parallel and you couldn't correct the arch. Oded
  3. a couple of points: after very carefully lining up the crack (dry, no glue) I glue the cleats in place. This holds the repair in place when I later apply hot glue on the varnished side. I sometimes loosen the upper screw a bit and ‘pump’ the glue into the crack and then reset the screw, always checking for alignment. I use 3x5 card stock for the paper at the base of the pillar. To speed things along I put a dab of very thin hide glue on the plate and use ca glue on the pillar to get an instant bond without introducing ca glue to top wood. I like using the magnets, despite the fact that they can be a bit tricky, because they are light weight and this clamping method does not impose any torque on the plate and allows you to more easily handle the plate. Oded Kishony
  4. I got my magnets from K&J Magnetics. https://www.kjmagnetics.com/proddetail.asp?prod=D84PC-BLK The thumb screws, both brass and nylon can be purchased from an industrial supply like MSC or Grainger https://www.grainger.com/product/GRAINGER-APPROVED-Thumb-Screw-4NHT8 or on Amazon https://www.amazon.com/Knurled-Head-Thumb-Screws-Machine/dp/B01729GGR2 or nylon ones at Home Depot https://www.homedepot.com/p/Everbilt-8-32-x-1-in-Nylon-Knurled-Head-Thumb-Screws-2-Pieces-26388/202209622 Oded Kishony
  5. Would your measurements reveal improved responsiveness? Did you check for that feature? OK
  6. I've tried various versions including an off center motorized twirling device clamped to a cello bridge. It made a huge roaring racket. Didn't seem to help the instrument very much (didn't hurt it either) I met a vioinmaker, years ago, who connected a violin to a radio via speaker driver with a stick glued to it, touching the side of the bridge. He claimed that when he first set it up he had to crank the volume all the way up to get any sound but over time he was able to reduce the volume setting significantly and the instrument worked very well as the 'cone for the speaker. Or you could try Micheal's gizmo. I don't think it matters too much what you play through the corpus (Limbaugh will ruin it though ;-) but this is something you could do that will not offend your wife since it will just be another audio device playing. Oded
  7. This photo illustrates how you can use this clamp to align a crack that has a 'step'. Notice on the right side of the crack is a narrow wedge that pushes against the screw shaft effectively pushing down that side of the crack. To glue the pillars in place I put a dab of thin hide glue with my fingertip on the surface, let it dry a bit and use ca glue on the pillars that are surfaced with paper (I use 3x5 card paper). Oded
  8. I use this flanged nylon knurled screw and a brass version with the corresponding tap. The lower screw is used to pull the clamp together, so the hole on the left is slightly oversized to allow for some degree of movement and the opposite side is drilled through and tapped. The upper part, drilled and tapped on one side, is used to spread the clamp.
  9. I've developed a clamp and procedure for this that works very well. The shop made clamps using hardware that costs apx $0.25/clamp plus scrap maple two drill bits and one tap. I use plastic covered rare earth magnets instead of clamps because they are light weight and clamping pressure is only vertical (no torquing from clamps). The plastic prevents scratching and glue does not adhere to it. Magnet clamps can be a little tricky to control. I 'park' the magnets alongside the cleat then slide them in place, lifting the one that goes over the cleat. If you get the magnets too close they tend to 'jump' out of control. I dry clamp everything, checking the alignment with a straight edge across the crack, glue the cleats in place then after the glue has dried apply glue to the warmed varnished side. Glad to answer any questions. Oded Kishony
  10. To discourage the bridge from warping after being straightened, I make a thin solution of aliphatic resin (wood) glue and soak the bridge for an hour or so after it's been straightened (using MD's method), I then wipe the bridge with a paper towel and buff on a piece of cloth or very fine abrasive.
  11. The same is true for some organic dyes such as madder, the purpurin fades immediately but after that the color is very stable.
  12. Those that know me are probably not too surprised to see me chime in on this topic. ;-) I have long (perhaps too long) advocated for the idea of voicing instruments before varnishing, (but perhaps after sealing) with the instrument 'in the white'. I've been developing a methodical system for accomplishing this which is based on the reciprocal or bi-directional relationship of the surface of the instrument and the strings. Simply put, the strings drive the surface in the same way that the surface drives the strings. In practice this means that when a string vibrates it creates various patterns of vibrations on the surface, if the surface is tapped, the strings will vibrate in response to the specific acoustic profile of that area that is being tapped. In this way acoustic 'targets' can be chosen and modified. Further, as an area is being modified other frequencies are also affected, this can also be observed. Any surface of the instrument is open to modification (think ribs). Individual strings and frequencies can be isolated by damping all but one string and/or tuning it to the desired pitch. The instrument can be then played and an assessment of the changed be determined. The changes are normally not huge, on the order of a sound post adjustment, but they are cumulative. Occasionally a dramatic change is heard, which I believe has to do with a psycho-acoustic phenomenon having to do with filling in missing harmonics. The lighter the instrument the more effective the adjustments. Because the scraping is done on the outside and, subtly and mostly imperceptibly alter the arching, some of the acoustic changes may survive regraduation. I usually combine the use of the reciprocating vibrating strings as well as a spectrum analyzer to make adjustments. This 'tuning' method is wholly compatible with the working methods of the Cremonese violin makers because they finished the instrument from the outside after it was assembled (see Roger Hargrave) Will all the acoustic changes survive the varnishing process? Remain intact forever? Make the instrument sound worse? Everything is possible but one must compare it to the alternative, where one is more or less stabbing in the dark and if luck is with you the instrument sounds fine. Admittedly after having finished an instrument and playing it in the white I've opted not to risk making any changes. But this approach does open otherwise unavailable options for the violin maker. Oded Kishony
  13. It may be possible to remove excess iron by chelation. Oxalic acid would be a reasonable choice. https://en.wikipedia.org/wiki/Oxalic_acid Oded
  14. The deleted section was a discussion of the effect of aging on the instrument, the possibility that playing an instrument over a long time period enhances and increases the amplitude of the harmonics. OK