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HoGo

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Everything posted by HoGo

  1. I don't see lot of work in there. He downloaded CAD model off internet and just did the rough work of blank preparation and some jigging up for his CNC. The rest of the fine job he just hacked - gluing without clamps, setup not done etc. I think this video was mentioned few months ago and I called it a "pure definition of VSO". You can actually play the cheap chinese VSO's after basic setup but this one is not intended to be played in the first place.
  2. Are synthetics considered vegan? They are made from petroleum which comes from long dead organic stuff including zooplankton which are technically animals in vegan terms (just like shellac bug etc.). Funny are folks...
  3. look down on the linked page: IMPORTANT NOTE: not recommended for playing; ROFL!!!!!!
  4. From mandolin maker's perspective.... I use sandpaper for fitting mandolin bridges. Especially in initial phases and later fine grit that acts mostly as marking tool instead of chalk when I remove wood with scraper only. The mandolin bridge with something like 12cmx1cm contact surface of ebony would be bear to fit with just knife and chalk. And given the simpler arch of mandolin only rarely with spot deformations there is no reason not to do it that way. The tiny area of violin bridge feet and often scarred surface of top under feet just ask for simple hand fitting with knife. On new factory fiddless with bulletproof fiinishes I see no problem using such device but in those simple cases good luthier would probably be finished with the knife and eye before you set up the bridge in the device for correct angle.
  5. I've used old Stanley Bailey #6 plane for my centerjoints with no problem. We checked the plane for flatness (my FIL was machinist - grinder for airplane parts) and it is nearly perfect (better than my new Stanley sweethreart 9 1/2) and I guess it will stay such for few more years to come. BTW, making block planes is fun I made one after seeeing Davide Sora's toothed plane in old thread. I made it not 90 degrees but something like 65 degrees so when standard blade is bevel up the angle is close to 90 but I've used it with blade bevel down with great results on curly maple. (I used older plane blade I had laying in the shop for years, I cut teeth with fine triangular diamond file).
  6. He could use tungsten. Or gold, though that would be a bit more expensive.
  7. HoGo

    The Long Arch

    Yes, those bodies are the same (I believe the scroll is not the same, either changed at some time or heavily modified, but you need to look at original pictures and not my screenshot). You can see the scratch in the varnish of the upper bout that became black dirty one in the recent pic. The flat part of back is actually cropped bottom of the picture (by me) as I wasn't really interested in back arches here.
  8. There are MANY different kinds of fish glues. It's impossible to generalize.
  9. Density of lime can be all over the place from styrofoam like to heavier than both poplar or willow, and in my experience it splits/cracks easier than willow or poplar so the backs may be prone to splitting. I think it would be good candidate but watch for properties of the piece you have.
  10. HoGo

    The Long Arch

    One must be aware of the effect of modern lighting. The central arch generally gets a lot of light from side source and the typical neutral grey backdrop reflects in those parts while the parts shaded by the fingerboard and tailpiece will getmuch more contrast with background creating slight optical illusion that the center is more sunken than it really is. If you zoom into the Kreisler pic above you can see how the dents under bridge feet create a fake line of arch that is hard to distinguish on small screen without details. I did some work on the old pic of Diable and recent one from Biddulph. The arch on the old pic is VERY close to perfect circle all along the curve visible (except slight dent in the bridge area and very slight bulge under fingerboard) the recent pic has a bit more bulge under fingerboard and flatter aree in front of bridge. The curvature graph is not perfect - I used five points to define the curve of the arch in Photoshop which doesn't use curvature continuous splines so they create the kinks in the curvature graphs. The yellow line is perfect circle for comparison. Also notice the distortion of the outer f-hole edge...
  11. I've read this so many times but never seen any real DATA. I don't want to advocate use of these glues in inappropriate places but some of these ideas are at least partly hearsay. You can clean standard PVAC (not waterproof) with vinegar solution and don't need to remove wood. Of course using clean water is easier. I've read many times that white glue will not stick to surfaces previously glued with PVA but never seen any tests. Guitar folks mostly reglue guitar bridges with Titebond as was used in factory and they hold just as well as original and noone really cleans the surface of spruce top too aggressively to put a hole through the top - most failures are caused by overheating the instrument and release quite cleanly.
  12. HoGo

    The Long Arch

    Here is pic of the three violins exhibited by Vuillaume. One of the oldest photos of Messiah (center) and du Diable (right). The arching of du DIable is noticeably less flat than today (Biddulph pics) and also the scroll looks completely different from current scroll, at least to my eye. These things are somehow evolving over centuries...
  13. HoGo

    The Long Arch

    I contacted LOC year or so ago with this issue and after month or two they sent me the correct pic but didn't put the correct one into their online library, yet. Here is the correct one, BTW. Looks like it has quite smooth arch withoout flat area in the middle.
  14. HoGo

    The Long Arch

    That is not Kreisler, Don. The LOC pics are mixed up with some other violin (presumably Strad). Kreisler doesn't have an ebony crown on button. Good pic to see is pic of the three violins Vuillaume exhibited - Messiah, DU diable and one more Strad if I'm not mistaken and compare those pics to recent pics of the same violins. You can clearly see some diffference in top arch. I'm not at my computer so I cannot add the pics but they can be found online quite easily.
  15. WHY would Moldovan luthier be involved in the first place when she would already have paperwork at the entry of the country. There's something fishy in the whole story. I guess she just entered Moldovia without any papers and upon exit she got caught with valuable violin (that would put all blame on her) and local luthier considered it valuable enough to call it "national treasure". This term is commonly used for historic artefacts residing within country (no need to be made there) so they cannot be easily smuggled out.
  16. Did you brush the TO? I've used Tru-oil on gunstocks and couple of my mandolins and it works great. There is also the Tru-oil sealer/filler. I don't know composition but I heard it has higher "resin" content (whatever they mean by resin) and works nice as well. I only used it few times on retouch spots on mandolins . It is recommended under Tru-oil finish. BTW, I had older bottle of unused TO that turned into jelly - you really need to transfer the unused TO into better bottle with tight cap to prevent drying in the original bottle - and I used the jelly (still sticky) as ground on my campfire violin I was revarnishing and it created beautiful smooth base in one ot two rubbed applications. I also applied the topcoats as rubbed glazes layered with oil paints (alizarin/madder red and umber).
  17. That sounds very reasonable. If you prevent using too much of the filler/ground substance than the amount is relatively small and the actual material is not as important as the job it does (looks good and makes good surface for next stages). The Hargrave POP ground actually gets mixed with first finger application of thick varnish creating slurry of POP crystals with varnish in the few outer cell layers. But if you manage to apply just varnish or thicker oil to do the same job the only difference would be the weight which is slightly larger for POP crystals. BTW, the "Firnis" mentioned in the article posted above is called "Fermež" here and has been sold forever in paint stores (even my father's grandfather used it) as a base coating under oil paints or for making windowsill putty and othe rsimilar tasks. I don't know actual recipe but it is yellowish thickened boiled linseed oil that dries overnight in thin layer. I did some experiments with fermež and my own boiled linseed oil (boiled with lead acetate) and it gives similar results to the oil, perhaps penetrates a bit deeper on maple. The oil creates nice satin smooth surface on maple. I didn't do tests on spruce.
  18. Without seeing the pictures (you cannot simply copy/paste them into post, it's best to use "upload" dialog to post pics) I would agree with Davide. I would keep some space between the pillar blocks used for clamping so you can glue some substantial cleats on both sides of the repaired plate, by substantial I think of 5mm maple straight across the joint. I would keep these on there as long as possible and the one placed where the lower block will later be glued I would remove only right before gluing the plate onto ribs, but add normal cleat on the underside just next to block when plate is finished from inside. For gluing use quite watery glue and heat the area thoroughly to temperature above gel temperature of your glue. You may want to paint some hot water on the plate along the joint (1-2" from the joint) right after clamping so swelling of the wood will help keep the joint closed. (some folks do this after rubbing joint together) Hopefully the sresses will be relieved by the time you finish the plate and thinner edge of plate will also put less stress on the joint. Do a dry clamping run to test how it will go.
  19. It's rosewood and it glues well with thin CA glue. just one tiny drop on te shaft of the ornament will hold it. The thin glue will easily penetrate hairline cracks and the bond is very strong unless there is mess of dirt inside. You just put a drop (or few if the crack is long) on the crack and it will wick inside, better if you can press the crack together few times, it will suck the glue in, press it hart together for 15 seconds and leave it harden more for few minutes. Scrape off leftover dry glue with razor blade or such or quickly wipe with acetone while not cured. Don't get any of the glue on your violin (watch your fingers and any spills) as it wil eat into any spirit varnish. Preferably remove the peg from instrument for this work.
  20. Don, while I'm nowhere near pro in CAD modelling I got some experience drawing instruments in 2D (working mostly through Photoshop/ Illustrator combo from photos and from CT scans) and 3D (mostly Rhino). I believe that generating cycloid is doable in Fusion (and possibly in Rhino) and likely the variations of the curve as well, but connecting them into one smooth surface with full control over the inflection points is something for a real CAD genius. Arching of instruments is not as simple as it looks and if you add some specific conditions it gets very hard to model, not even thinking about something like full parametric model. One of my customers was desidner in automotive industru and I showed him my work on F-5 mandolin in Rhino (I was barely starting back then) and he laughed about Rhino being unable to handle the task and that Catia is the SW to use so I provided him with some of my data - crossections and plate outlines etc generated from CT of a Lloyd Loar Gibson mandolin and he FAILED miserably. He agreed that is really hard to model all the smooth transistions when the crossections don't correspond to perfect mathematical model. Car hoods are smooth but they can be typically split into separate areas connected with an design edge or some simple transition while on violin you want it smooth in all directions. For me the best approach was using several crossections to generate points at given heights and from there cereate topographic arching map and from that the resulting surface (usually not in one single piece but curvature continuous connected pieces). I think if your original crossections will have the inflection points in desired place, the generated surface will be close enough, certainly counting with that the CNC cut will leave some extra wood, 0.5mm or so, on the outside for final smoothing which will allow for some tweaking after CNC does it's miracle.
  21. Isn't alum slightly acidic? Liming works by neutralising acidity of resin I guess.
  22. Perhaps I missed it, but did OP post rib measurements? The pic does make the APPEAR high but the phone lens do that all the time and mislead especially on close shots.
  23. Once I had piece like that. It was Engelmann spruce. Almost felt like I can bend the uncarved thin edges of the top around bottle. I used it for mandolin top and left thicknesses some 50 % thicker than normal. Sounded nice though a bit different, more dark/woody sound (but not bass heavy).
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