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  1. plate tuning specs ?

    I don't think you can be so sure about the arching, especially on the "thinner" violins. I've seen some violins with "camel back" arching that were not even 100 years old and well within "Stradivari style" thicknesses.
  2. plate tuning specs ?

    Siminoff has been even further off the tracks than CMH. lots of smoke and mirrors in his theories. Likely he haven't built more mandolins than the two or three he photographed for his books on building and since they have been the only printed spurce for few decades there are rows of his followers who bought all of his snake oil.
  3. From my experience, the effect of strong medullary rays in OP is sometimes called "silking" in guitar or mandolin world and typically folks like the appearance. Some spruces tend to have less of it (red spruce) some more and individual trees differ as well. If the wood has strong medullaries you will hardly get rid of it completely even if you use scrapers or rough sandpaper. Any stain (even light colored) will bring it out more (think of quartered oak) and rougher surface of the rays will take more color than polished smooth so the contrast between the rays and softer early wood will be more apparent on wood sanded to a very smooth surface.
  4. Classical guitar builders have commonly used spanish cedar for necks, backs and ribs and mostly use HHG. I see no problem. If you ar not sure, wipe the joint with acetone before gluing... Many most Martin guitars before 1930's had Spanish cedar necks and used HHG for assembly and they are not falling apart either.
  5. !8th century working methods

    There are few such water-powered sawmills still in working order (though a bit modernized during 19th century) in our country... Usually up in the mountain walleys with deep forests around so the logs were easy to get there and only finished lumber was brought down to town... They even had water-powered planer in 19th century. few pics
  6. re-gluing the fingerboard

    Using CA for fingerboard? Yes, I've seen it in chinese factory!
  7. There is another option to geometry

    There is long list of possibilities how to aproximate curves to any given precision. Starting from zillion of linear segments ending with NURBS (non-uniform rational b-splines - that's what CAD uses) and all kind of curve types in between (polynomials, goniometric functions etc). What exactly they used we will never know, but with certainty they had dividers and could draw lines and circles. The arches (and body shapes) are affected by precision of original maker, distortion over time, arching repairs etc. so we cannot judge from how they look now. Even if you start with perfect circular shape and put it under tension the shape will likely slowly creep towards catenary... There are numerous past discussions about these curves, take a time to read them.
  8. First Time Violin Repair

    If the owner doesn't want to practice top removal (which can be a PITA for factory instruments glued with white glue or such) I would glue cleat to the end of the crack through the treble f hole before attempting to partially loosen the top from ribs just to prevent further damage during manipulation. Also I would check if the crack can be closed without any loosening of top from ribs. I think after removal of nut, strings and soundpost the crack will close with little clamping pressure, perhaps use some wedges between the clamps and the top to align the crack edges. The neck appears to have broken heel, the heel never parted the body and someone glued the neck back in place. The glue line looks fine and even though the repair person used Titebond the neck can be good enough (if it was originally set well).
  9. Conforming f-hole templates to arching between c-bouts

    You can construct something similar to pin router but with pencil instead of router bit . Make flat template from the poster- photo or 2D drawing out of thin plastic sheet (you can use clear over the poster and just trace outlines), cut out the f holes and place the top on the template with sticky tape or such. You can just use soft pencil in your drillpress and thin pin in the flat table and put a dot every few mm around the f hole and then trace it by hand. Or make some device that will allow the pencil slide up-down with minimal force (round pencil in a matching tube held in chuck of drillpress) and you can go all around in one move.
  10. Beady eyes... extreme version of fisheye

    One more question... does the beading happen when other (good- proven) varnish is applied over the dry "bad" varnish? I would like to know what is the stuff that makes this happen as there may be other chemically similar thinners that can do it...
  11. Downforce Experiment

    IMO, this is not math but more of a physics exerise so rough estimates of downforce are acceptable, even if not exact to 1/8 of a %.
  12. Beady eyes... extreme version of fisheye

    Did you try to apply it over another dry varnish?
  13. Downforce Experiment

    Hey Carl, did you measure how much the pressure changes when the string is displaced by 2 or 3mm like during heavy bowing? And how much that would change with varying break angle?
  14. Downforce Experiment

    I like that example. I'd add that on the othe rend of spectrum there is banjo with very heavy and rigid rim and tonering with two metal rods adding to the stiffness against string tension so most of the energy is transfered via light bridge into light tensioned plastic head but the neck makes for huge difference in tone (necks can be easily changed without chenging the rest of instrument at all). It somehow "filters" out some frequencies out of the spectrum and various wood combinations give diferent tone.
  15. Downforce Experiment

    When you inmagine bow (shooting) and pull the string a bit it will pull the ends together, if you pluck it the ends will vibrate if you put a stick between handle and bowstring to act as sort of "bridge" and pluck it the vibrations will still be there at both ends (though slightly different) and I cannot see why the energy would transfer just via the bridge and not ends of string directly? I always thought of instrument vibrating as whole, not just top and back and the strings hold the whole under constant tension until string is plucked or bowed and the vibration causes (however) tiny changes in the tension it must have some effect on both ends. I have no idea where this thinking fails. Perhaps I'm over simplyfying things... I often tweak my instruments in white (not violins but f-hole mandolins are relatively close) and changes in neck stiffness can have large influence on tone.