HoGo

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Everything posted by HoGo

  1. I guess Manfios "Hilbilly CNC" might be called apprentice in other parts of world :-)
  2. Perhaps but you need some extra wood under bridge for the feet and soundpost pressure and some behind and forward of bridge wher eteh most of the buckling appears so you end up with thicker centerbout and thiner upper/lower bouts with this reasoning....
  3. Once you do a few of them it's simple. In most cases the CNC cut fretboards and standard saddle compensations of factory guitars go perfectly with standard gauges of strings. But some players use nonstandard strings or nonstandard setup requirements (like for bottleneck playing) that require additional compansation at nut. I've seen more than few examples where fingerboard was cut by hand and fret positions not very precise and some where the frets were precisely cut using template but the nut end of fretboard was (by mistake) left mm or so longer (rarely shorter). One has to grasp the no
  4. It's impossible to argue about that without knowing what IS "classical arch". We can only guess how it originally started by seeing today's shape. I would say that all classical instrument started with classical arches (that's how I would defina classical arch) that evolved into what we see today but no one living was there to report what it exactly looked like. We cannot call current shapes classical or we could consider the "camelback" in one of the examples above or any weird arch of multiply patched Strad a classical arch. Re. turning "thousands of through curved long top arches" into
  5. Every time a solid object bends there is a neutral axis where there are no stresses but the further in crossection the material is from this axis the more it gets stressed, the outside is under tension while inside under compression. So the outside stretches and inside of the bend compresses. On every material, even with tiny force. There can be elastic bend with smaller forces where materal is still able to get back to original shape after force is released but with long time stresses the deformation becomes permanent. Wooden archery bows will weaken after some time and even snap eventually d
  6. Sure you can finger wherever you want. The OP asked how to adjust the nut so the fingering positions will end up more perpendicular to neck axis. On guitar this is brought to extreme with fixed straight frets.
  7. I remember my first oil varnish cooking down in the basement of the apartment building with hot plate down right on the doorstep potentially blocking my way out. Somehow I lucked without fire and none of 16 neighbors complained :-) I was 15 back then and would strongly suggest do it FAAAAAAAR away from any building. I wonder if one can heat resin without oxygen similarly to "torrefied" wood (dry or wet process) and if it would also darken...
  8. Isn't standoil made by heating linseed without presence of oxygen? Anyone knows how it is produced?
  9. David (Beard), you probably missed it but no one stated here that the top and back arches on Cremonese violins started with the same shape or height (you know this from flat back viols...). The only thing stated was that they do deform in a somewhat predictable way (though hardly predictable amount) for their whole long life. When there is force there will be reaction, the wood is not perfectly stiff or fully elastic material. The hypothesis (and supported by laws of physics that are not to laugh) is thatthe top arches started with less flat top arch than what is generally considered "classic"
  10. On guitars it is mostly the tension and thickness of steel core that creates need for compensation and height of nut (some players prefer higher nut than minimal standard). Perhaps mixed sets of strings on cello could cause problems as well.
  11. I've done this to guitars and banjos. There are several ways of doing it. One is adding shim to front edge of nut (or in some cases I made L-crossection nut that overhangs the fingerboard - not simple on arched boards - but makes the nut one solid piece), the other is reducing the fingerboard by some amount adding a bit wider nut and cutting negative compensation into the nut with small round file (at 45 degrees) so the edge where string leaves is at correct relation for true pitch (on fretted instruments it is easy to do on strung instrument as the nothes are higher above board). I guess on c
  12. Perhaps they would at least add a peculiar taste to a smoked meat?
  13. Rosewood can be stripey or quite blunt dark brown... Here is Catnips bench with violin with Rosewod board: (scroll down) My friend has bass that after planing showed fresh striping of Macassar ebony. We thought it was ebony before planing. Old rosewood darkens and stain and sweat can cover the color completely over time. We left it natural but it eventually darkened again after few years of use.
  14. There are redwood trees planted in parks here too but not for commercial purposes. This link is again interesting, they call the siding redwood which is according to them scots pine but the actual product I see IS spruce. SUre sounds more exotic. This is marketed around here also as "baltic" or "nordic" spruce siding. Pine has distinctive reddish heartwood while they offer pale colored siding.... The northern spruce trees grow smaller and knotty which gives it the appearance.
  15. The nubmers in the chart above don't look correct to me, quite a few of them appear too high to me. The mahoganies, spruces and several other species. Also Ebony is not always denser than water.... And anyone heard of European Redwood? Indonesian is more often called Macassar Ebony, nice wood but often stripey. Some guitar makers love it for back and sides. If you stain it black it looks just like the african (common) ebony
  16. Thanks for your input, I'm looking forward to your findings. I spent the weekend rereading all the Roger Hargrave's articles on Amati method and he notes that the longer patterned violin (he mentions Vieuxtemps) appears to fit the mould but the upper block was either fitted proud and ribs made with gaps around the upper mould or it was built up with some thin strips of wood. Some articles (from other authors) about mould geometry mention the larger mould being wider at bottom bouts (like your rib compariison). That seems contradicting unless there are three differing sizes of del Gesu's.
  17. Thanks for response, that's interesting... I'm a bit puzzled now. I scaled both CT scans to real size and got slightly different comparison. They are a bit blurry but good enough to tell the basic story. In my overlay the Kreisler ribs are approx. 3 mm longer than Plowden (that matches difference in published back lengths of the two I've got 353.5 mm vs 351 mm) and the lower bouts match while the upper bouts of Kreisler are larger (Kreisler is 167 mm wide -from Biddulph- and Plowden should be 164 mm). BTW, my pic is flipped to match back views. Lower bout widths are 204 mm for both violi
  18. When you look at the violins witch "camel back" it is clear they didn't start that way so similar amount of distortion can be part of any other violin of similar age and similar top stiffness. Of course it is impossible to tell exactly where they started and how much they deformed over time. The arches of many(?) were corrected to form that restorers believed to be correct and many were thinned or breast patched and modified so we can only speculate. We can probably look at some of the healhier "thick" del Gesu violins as they certainly spot less distortion versus those that were thinned
  19. No big curve, as I noted before the deformation in length is tiny and so is any long bend of violin body. The back is rigid and being stretched it (mostly) keeps the flat plane while the top gets the compression load and tries to "wrinkle" under the load. Also along the long life of the violins the ribs were commonly adjusted or re-fitted by restorers, sometimes planed...
  20. The distortion is real, nothing magic about it, plain laws of physics. Just like any old car will magically and accidentally transform into pile of rust if left in the weather. The Cremonese makers (and especially Amati's) were prized mostly because they were the biggest (and for some time sole) producers of these beautiful instruments for nearly 3 centuries. Many of the guys further from Cremona made just VSO's of the time (now prized, but then they just filled demand for cheap instruments for general public). One should remember that for part of their life they were strung with gut
  21. What is well built? If you put strings on anything it's gotta bend. Laws of physics. Even thick steel profile would bend with violin strings stretched over it, though just fraction of a mm. Keep the force for hundred years and it will even stay partly in that bent shape after releasing the tension. Wood is no different and it will necesaarily give a bit under tension and if you measure new instrument without tension and after stringing (and settling for some time) you'll find where the stresses go. I mostly work on mandolins and they tend to form bulge behind bridge as that area is unsupp
  22. There's no need for such stretching/compression at all. If we simplify the arch somewhat and calculate with smooth circle arc long arch then shortening the top outline by mere 1mm in length will cause almost 4mm bulge of arch in center (assuming there won't be any wood fiber compression aong the top). Now, if you force the apex with bridge to stay at the same height the bouts will bulge drastically...
  23. Hello folks, I'm reviving this old thread of mine. I didn't do much more on Kreisler drawing, I had a lot of other work to do after the first lockdown was unlocked but now sitting at home office during much longer lockdown I managed to peek into my old files and catch on. In the meantime Plowden del Gesu got into my attention and I started comparing several Gesu violins trying to understand what has been repeated many times - del Gesu supposedly worked off one form (or perhaps two) except some of his earliest violins. I searched the world for any measurements of his violins and posters CT scan
  24. Looks cool. I've mentioned these math and computing methods waiting to be used few times before and now it's taking shape... I haven't read the article yet (just peeked inside) and I still don't see the most important point of all - connecting the data with actual sound of instrument. You can predict frequencies of plates or determine which piece of wood will get you there etc. but that still is not approaching the practical outcome of violinmaking. It's hard (or close to impossible) to quantify quality of violin sound without pretty heavy research of it's own and even with that there wil
  25. I think there is confusion around here about what "fast growth" means. For ordinary folks it can be growing to height (observing trees in forest without knowing what's under the bark), for folks looking at lumber it may be growing to width (observing) just growth rings. But for foresters it is often growth of VOLUME. I've got many friends who are foresters and I used to be in touch with folks at local university of woodwork and forestry and their common research was about yearly increase of volume of wood per hectar of forest in selected locations and forest types. They would measure each tre