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HoGo

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Everything posted by HoGo

  1. One needs to accept the fact that there is no place here pure math proof theorizing. If I win lottery does it prove that I can predict the numbers? Of course I could just be lucky. If someone will tell apart the violins or wines consistently with low error rate then he can be certified as expert.
  2. We know about the "one mould theory" but in this case I'm interested in approach at copying a certain violin (not exact bench copy). I personally lean towards using back purfling as the main source of outlines not the ribs CT. I'm not sure if the bulging of ribs was there (at least partially) when the instrument was built (so the perspective mould should copy that) or majority of the bulging appeared later as result of the years under tension and back is closer copy of the mould.
  3. I just found out there are some nw interesting things published on https://www.strad3d.org/ Lots of good resolution photos and CT scans of whole plates rim and also crossesctions of two Strads and the Plowden del Gesu. Nice set of precise measurements as well. I just put the back photo into Photoshop and after quick resizing the basic four measurements of back are within 1 or 2 10ths of a mm from the published numbers. Looks like there is very minimal distortion in the pic. I'm working on some simple drawings of the Plowden and will post them (may take few months to finsh it). BTW, queation for experienced makers.... The ribs of the Plowden appear to be quite bulged in some areas. In such case would you prefer using back as main source for outline of instument "inspired by Plowden" or the ribs CT crossection (taken through the middle of the ribs) which would result in slightly larger outline when overhang is added.
  4. HoGo

    Crack assessment?

    As I look on the top, the dark grain lines appear to be filled with something (filler or dark varnish) as there are areas that also show bare thin dark grain lines just left of the foot and the two offending lines appear to be among the thickest of the well-filled ones so some cracking or peeling of the filler from wood may be there. The reflections may make the cracks appear deeper than they really are but the shrinking filler can also pull some wood fibers with it...
  5. Maybe I was lucky but my old #6 STanley-Bailey is as straight as it gets. (It was great gift from bow maker Bill Halsey) but my knock-off #4 had to undergo truing of the sole. I could just call my FIL to grind it - he was one of the old school machine grinders working down to 1000s of mm (aircraft engine parts) who everyone called to do precision jobs that others couldn't do., but I just tried the sandpaper and it worked sufficiently. My FIL told me the half of the precision work was knowing how to hold the piece and the other half was knowing your machine inside out - that meant knowing what part of the machine had seen more wear or has possibly moved due to tensions etc.
  6. I would think a'la Davide Sora (as he shows in his videos). I believe using bandsaw to saw out neck profile or plate outlines is normal these days. Thickness sanders or CNC carving or purfling channels routed less so. I'm just curios to compare to my mandolin making. I found out I spend more and more time on my mandolins even when I improve my technique or some fixtures I still tend to spend more time on tiny details (just to be more period-correct) then on previous instruments. I can estimate my F-5 mandolin build (fully hand made, minimal use of power tools) to be close to 300-350 hours of work. Sometimes maybe more.
  7. But you can use the cheap willow or poplar from firewood stash instead of expensive highly flamd maple. BTW, what is the typical hour estimate for a violin by maker who does most of the work by hand?
  8. I guess he meant BLO. Boiled linseed oil.
  9. Here is another comparison of Plowden and Cannone. The cannone drawing was from internet I'm not sure how precise it is and whether it was corrected for symmetry, but it certainly adheres to the same basic mould shape everywhere except near corners.
  10. That's what I'm doing in Photoshop and they are all surprisingly close even the larger ones like Kreisler match Plowden form very well, just extend the upper andor lower blocks tiny bit and reshape the point blocks. Here is quick comparison of Plowden and Kreisler ribs I posted some time ago (Kreisler is the darker longer one)
  11. I'm in similar situation as OP. I've got several dG violins in photoshop and comparing the backs and CT scans of backs or ribs (all resized to full size) and considering symmetries Plowden comes as one of the candidates. The symmetry is stunning. I remember R. Hargrave suggested looking at Du Diable years ago but that one doesn't have the corners as symmetric as the Plowden.
  12. Those appear to be similar to (re)sharpened new files. New files are duller because they are heat treated after the teeth are formed so quick sharpening makes them work much better. I've seen several DIY methods of chemical etching to sharpen older files. Never tested them but they can work as I know folks who used it. The company that Michael D mentioned uses different process.
  13. I'm not competent enough to say anything about the arching but I think you should re-do the video... draw thick (visible) soft pencil lines right across arch where templates would be normally used and along the centerline and show those at low angle. Also using low angle soft light (like single bulb on bench level) in darkened room would reveal much more about your arches (even to you).
  14. HoGo

    Split cane bows

    I wonder if he rotated the split cane pieces 60 degrees for glue up (they're showing the grain)? AFAIK, most split cane rods or arrows are made with the outer hard/strong layer of bamboo left as is on the outside of the rod/ shaft (except minimal smoothing at nodes and some final smoothing).
  15. I guess he meant the channeling around perimeter of back is quite pronounced.
  16. I see the older Strad posters just as nice wallpapers, not as technical drawings. Even some of the measurements are sometimes questionable (when you compare numbers from several sources like Biddulph book they are sometimes off, you can only guess which one is correct). The newer editions seem to be better in terms of dimensions but still not perfect because photography has its limits. Often you can see that the Photo editing for the posters or books likely cropped the very edges of plates that were too shiny to discern from background. That might result in inconsistency in outline dimensions. When I wanted reliable outlines I scanned poster into PC, scanned/ downloaded good photographs and found out all measurements of given instrument from as many sources I coud. I take one good picture of back as base (preferrably CT even if at lower resolution) and measure precisely length/widths from picture (keeping eye on possible cropped edges) and calculate how much I need to enlarge/shrink the picture to get real size (in percents). Usually I find that widths percentage matches closely or the percentages grow from upper to lower (or vice versa) suggesting the picture was taken with center of lens above or below center of body making upper or lower part wider. The length percentage from posters rarely matches the widths which is indicator that printing process was not carefully done. With a bit of transformations in Photoshop I can get the outline match measurements very accurately (assuming you best guessed which ones are most reliable). Then I follow and resize other pictures to match this one - you can often match partial pictures by matching grain lines or dents and create patchwork of clear pictures that will give you good details of edgework. Tracing the shapes with good precision and not too much "smoothing" is another hard job, you need to know where to put the line. The position of f holes or exact shape of scroll is even harder to do because of the 3D nature of the curves and source outlines are highly dependant on quality of photography and direct measurements. Here the CT is best source. The CT scans apeear to be best source of precise measurements but need to be also printed in correct size on posters. Printing in correct size is no problem these days and good paper doesn't expand/shrink with humidity anywhere close to wood in the same conditions. I've produced some F-5 mandolin drawings this way.
  17. These scientists can analyze all day long and still there won't be generally accepted conclusion as all kinds of materials (glues, finishes etc.) could be contaminants during production or one of many later repairs. They can talk about what they found but never claim whose hand put it there and why...
  18. IMO, besides the tailgut material the weigth of the tailpiece (and perhaps position of its center of gravity between bridge and edgeof violin) may be the biggest factors in how much t/p affects playing properties.
  19. Agree. I've drawn arches in computer and really even the difference of cremonese back long arch from circle can be negligible. Top long arches are flatter but there have been long threads about very possible deformations over three centuries converging towards the "camel" arch.
  20. Could be something from Czech factory "Amati Kraslice" (formerly Graslitz) just across borders from Klingenthal? Before WW1 was part of austria/germany, also during WW2 annected to Germany...
  21. :-) Back in 1991 we were still together as Czechoslovakia, now I'm in Slovakia. I'm not aware of any high end steel production here, just plain construction steel and common grades of tool steels. I guess the PM processes are covered by patents of few big companies so they are not widely employed around globe. I became interested in the PM-V11 after the big antree and (being math teacher) considered their grading quite odd, to say the least, so I wanted to know what it really is under the fake name. Just from pure interest as my best edges are still old school "cast steel" laminated blades for chisels and my old Stanley #6 jointer.
  22. Taking credit cards means paying fees to banks or card companies so unless your business volume is large enough it is not worth the hassle, especially when bank drafts (transfers) within EU are so plain cheap (few cents) and simple.
  23. I think you mentioned below 1% Vanadium for PM-v11?
  24. The CPM-3V seems to have a tiny bit lesser edge retention but slightly easier to sharpen than what I suppose is the PM-V11 alloy. But if the PM-V11 is hardened to 60.5 only it may be very similar overall (the CPM 3V seems to hit higher in toughness)
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