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scordatura

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Posts posted by scordatura

  6. My "Kreisler Project"

    in The Pegbox

    Posted

    3 hours ago, HoGo said:

    I measure the bar pretty much exactly 15mm inside from centerline at bridge position. The bridge appears to sit with half of bass-side foot over the bar. I haven't studied too deeply what is considered normal value for this.

    BTW the top is dangerously thin at the bidge, barely 2mm or even less near the bass foot. Scary! I guess after many restorations and soundpost patch(es) the wood slowly vanished...

    Someone at some point went too far with thinning the top. By the way that is partially why the ribs have bowed out. Structurally the arch is weakened if the top is too thin between the f holes. A sound post patch is one thing but a chest patch is another. This is however not the only factor in arching or rib distortion. Most of the DG instruments have been regraduated. The thinknesses of the Cannone show what an unaltered or relatively untampered DG would have been. The good thing is that the Kreisler is an outstanding player's instrument despite the thin top under the bridge and less than conventional bass bar position. Normally the bar is slightly inside the bridge foot.

  7. My "Kreisler Project"

    in The Pegbox

    Posted

    I may have mentioned this before but the bass bar on the Kreisler is outside the bridge foot. That is unless the bridge got knocked out of place for the CT scan. That is unlikely as that instrument would be handled with kid glove care given the value and the people there at the scan.

  15. My "Kreisler Project"

    in The Pegbox

    Posted

    Good points. If my memory serves, there was arching correction or a sound post patch done quite a while ago. Additionally, John Montgomery has been maintaining the Kreisler. I am not sure if he has done anything major to the instrument since he took over from Morel. I do know that the instrument has been polished. I saw it this past summer and the appearance of the varnish has changed quite a bit from times past.

  20. CAD/CAM Software

    in The Pegbox

    Posted

    Francesco may I ask the hardware and software that you are using for your 3D light (I am assuming you mean laser) scan? Are you able to do your own CT scanning or are you using existing files? I can only imagine going to a radiologist and saying "would you mind if we scan a violin or two"! ;)

    By the way this is from Francesco's site. It is a high res CT scan. Much cleaner than some I have seen. This was done on a very nice machine! Note the Amati arching and compare that with  with Geigenbauer's Fusion modeled Conte Vitale viola. The Conte Vitale has a deeper and wider recurve.

     

  22. CAD/CAM Software

    in The Pegbox

    Posted

    3 hours ago, HoGo said:

    Wasn't the fluting carved after the f holes were cut on nearly finished top? We cannot count that as inflection but rather cosmetic treat. I guess before fluting the f hole wing was convex or nearly flat and it looked better to them to carve it concave.

    One needs to remember that the F hole wings are very active at certain frequencies. This has been verified with 3D animation. What may have started as a visual element has a distinct acoustic effect.

    https://www.bormanviolins.com/modalanalysis.html 

  23. CAD/CAM Software

    in The Pegbox

    Posted

    2 hours ago, HoGo said:

    Zebra analysisi is available in RHino as well and it works great to find curvature continuity/tangency problems of your surfaces.

    I think some steps he did in the video are unecessary or at least could be worked out simplier in Rhino (all the stuff with pints and curves in the beginning including removal of the offset line). Perhaps Rhino has better/ more functions for surface creation but I've never worked in Fusion.

    This is the conclusion that I am coming to. Rhino is better for surface creation. As I mentioned above, I am working on a workflow that will allow modeling in Rhino and importing the .3dm  files into Fusion 360 for CAM. I do not like the lack of native CAM in Rhino and am not willing to pay up for the RhinoCAM plugin. That being said I have not tried FreeMill.

  24. CAD/CAM Software

    in The Pegbox

    Posted

    6 hours ago, Geigenbauer said:

    I just came across this interesting discussion on the AUTODESK webpage.

    https://forums.autodesk.com/t5/fusion-360-design-validate/another-small-loft-problem/td-p/9201723

    I found the video at the bottom of the page (posted by TrippyLighting) very interesting. He is demonstrating how he would approach a loft surface with few profiles. Also a lot of practical tips included.

    There are some very good points in the video! The zebra contours is great for visualization.

  25. CAD/CAM Software

    in The Pegbox

    Posted

    10 minutes ago, HoGo said:

     

    I had old distorted instruments in mind when typing. texture of varnish and wood would not make it easy to find it and I guess it would vary wildly around the instrument (the CT scans often show how different arch can be on bass side and treble side). But of course the main schools will have somewhat distinctive placings of the inflection (Amati vs Strad vs Guarneri vs. Stainer)

    Yes this is the problem when working from CT scans. You have to do the arching correction which means bringing down the soundpost/treble side and then mirroring over to the bass side or the opposite if you work from the bass side. It depends on how tight (New York setup) the post has been and the vulnerability of the plates to distort. Splitting the difference between the high treble and low bass seems to make sense to me.

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