HoGo

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  1. Nice work Don! BTW I like the pyramids in the corners, they look cool (remind me of the pyramid bridges on guitars). How long did it take to cut the back as shown? The artifacts in the model are where there is no surface curvature or tangency continuity between the partial surfaces. Especially where the tips of the triangles meet even with curvature continuity it is almost impossible to keep that perfectly smooth as the width of the surface decreases to zero and all the smoothness is managed at microscopical level. It is better to create such surfaces using one contonuous "half circle" sweep through the crossections that will be connected smoothly to the rest. Perhaps leaving small window in the center of the half circle that can be filled easier smoothly with the surrounding surfaces. Of course the rendered model magnifies these effects in real CNC cut they will be completely negligible. Even some tiny "holes" in seams of the model can be ignored for machining as the tool will just jump over them (or the CAM will fill them). Of course if you want to do computer animation with the model the artifacts will be unsighty and need to be smoothed out. BTW, I believe Fusion has equivalents of the Rhino surface creation tools. They will be named differently or work a bit differently but I bet they are there, Rhino is not such special piece of SW.
  2. Sure it is... in that "toxic green" color :-)
  3. I didn't get full scans, just the top, back, ribs and few crosssections like those posted above but in good enough quality that the "rulers" were not blurred but sharp straight off the CT viewer screen. I found them on internet years ago and now I discovered them on my HDD among heaps of my old "interesting" violin related stuff...
  4. Hello folks, I managed to spend some time at the computer. I found better resolution CT scans of the Kreisler that had perfectly clear "rulers" on them in cm scale so after scaling them up to full size I got much better base pics of back, ribs and top to which I fitted high res photos of the thing (trying to match grain lines, pins, centerline and any obvious marks or repairs) so I got decent full size poster to trace. I did my best to make drawings as close to what I currently have (that may change if I get some better new inputs) I've got basic back and ribs drawing done in full size (A3) here: Kreisler-back.pdf Kreisler-ribs.pdf Plese feel free to comment... edit: I don't know it it would be appropriate to link this to the Addies pinned thread with his drawings? These drawings may prove useful for some...
  5. The dark wood is not winter growth but late summer/autumn and the light is spring/early summer fast rate growth. Too wide late growth can be sign of reaction wood. (compression on conifers)
  6. I think there may be vast difference between 90 degree and 60 degree v-slot. I don't think I've seen something like 90 degree v-slot on guitar. (I would like to see detail pic of such slot after some use). I've always done shallow round slots as I was taught and often even polished inside (on pearl it helps as it can be gritty) for unwound strings. I start the slot with 60 degree triangular file and then round it. I just have one guitar in for a new nut so I will try v-slots just to see... There are also flat wound strings for mandolins made by Thomastik with very fine wound a string and I've seen that bind in the slot as well. My impression is that players with agressive sweat tend to have problems with pinched strings especially if teh slots are left a bit deeper and dirt accumulates and string is sometimes as rough as tiny rasp where it sits in the slot. I can admit that mandolin or guitar players don't change gauges of strings often, generally they settle on set that they like and only rarely change that later. And rarely skip to different gauge perhaps set from other producer (which is usually very close or same in thickness, unlike some violin sets).
  7. I work mostly on mandolins and guitars and in that world v-grooves are a big NO (I've also set up and replaced nuts on quite a few basses, some celli and violins). Perhaps it's because guitar nuts are made of bone or pearl so they will not conform to shape of strings and v-shaped slots will definitely pinch the strings. Especially on unwound a- strings on mandolins, even if they initially work OK freshly lubed after some playing they will start to jump during tuning up or down - that is clear sign of pinched string. It's normal for guitar or mandolin tech to have nut files or saws in many different gauges to fit most common string sets and depth of slot is expected to be half of string diameter for wound strings and perhaps tiny bit more for unwound. No big deal to do it. It' pretty much expected standard of industry. I have covered gauges from 0.1mm up to 1mm in 0.05mm increments and above that I use tiny round files or thin sandpaper wrapped around some of the thinner files to match desired diameter. If you use v-grove, th emost important thing is that it must be cut as close to parallel to fingerboard board at the spot where the string enters the slot and gradually direct it towards peg. The worst cases of pinched strings I've seen were where the (deep/tight) v-slot was angled down towards head right from the leading edge of nut (or very close).
  8. when I need to cut crossgrain I angle the blade at least 30degrees of parallel but push it right across also slightly turning the handle to slice rather than straight push at 90 degrees. Minimal splitting that way.
  9. Strict vegan, I guess? Shellac is considered "animal" product by vegans. Then it is hopeless, I guess there were at least few bugs or worms in the corn used to make the alcohol as well... You can try some simple oil varnish... linseed oil and resin. BTW, isn't crude oil also animal product at least partially? So no mineral spirits or other solvents.
  10. I guess if every one taking any valuable item (even laptop can be quite pricey, or think of possible price of jewelry) would deal with them in fully law-compliant way (all the paperwork and checks at the customs at leaving and going back home) the custom offices would be completely full and airports would be blocked. One thing is law and other is whether it is really possible at all to enforce it fully at current flow of travellers...
  11. Kiln drying and roasting (or torrefying or baking, cooking ...) are two different things even some of the equipment used may be the same. Kilning is to dry fresh wood or get already dry wood to target humidity in conrtolled manner. Extreme kilning may damage wood but most wood cutters who know their business are doing it properly and result is great defect free wood. Often kilning is preferable to uncontrolled drying outside in a "shed" where fungus, insects or heavy checking may ruin the wood without you knowing it... I've done some simple baking in oven after reading many articles about thermowood or "torrefied" wood and you can get wood that is darker in appearance without any ill effects if you are careful. If I remember correctly I first heated the tops for hour or so at 100C to dry the wood to 0%MC then wrapped it in strong aluminum foil and carefully sealed with aluminum tape (heat resistant) to avoid oxygen (the big boys use nitrogen atmosphere) that would allow the wood turn into charcoal. I baked for 4-6 hours at 190C and got spruce that was slightly darker throughout and some of the resin got out to surface. After seasoning back to equilibrium humidity the wood remained a bit lighter (weight) than unprocessed wood. My test samples showed that different pices of spruce from different trees may darken to different shade. I made two identical instruments out of identical pieces of wood all from same logs (even fingerboards) and the sound was the same but the baked top seemed to be more stable to humidity changes. So even if that's the only benefit it may be worthwhile.
  12. There is small bluegrass / country musical scene in my country but not too many good instruments available so often when some of the better musicians travel to US they are asked buy some instruments there and bring them back. Typically this is just friendly act and rarely they get more money than the instrument alone and the checking it in plane did cost (usually checked by someone with no instrument of his own like bass player) . There is no guarantee of any kind just trust that the guy can find good one that fits expectations of the buyer. I remember times when I declared my instrument when leaving country to make sure no one will confiscate it on my way back but these days custom officers don't ask much about personal items. Once you do this as business its whole new dimension...
  13. In theory the gluing surface of button and the forces in the neck joint would indicate that the button could be sufficient to hold the neck in place alone BUT if any other forces are present (from side or just small fall of case) then ALL strength of all joined surfaces are needed as the button is undercut from top by purfling and often holds by just a 1-1.5mm of wood to the rest of back. Considering curly grain that can go pretty much at 45 degree in that spot there is almost no structural strength of the button itself holding to the rest of instrument so counting just with button is not advisable. Ironically repaired button with inlaid patch of straight grain maple could be stronger than original undamaged one. Since I work on mandolins I can tell that even with well fitted and tight dovetail between neck and block (that is really hard to separate), if the heel separates from heel button the gap clearly opens a bit so the neck moves with string tension. On mandolins the heel button is stronger and the button will hold neck with partially failed dovetail (or mortise) much better.
  14. Full CT scan is not a video. It's lots of data in very special format (DICOM or such) that can be viewed or evaluated by special software (that you see at your doc looking into monitor). Is such raw data included as well? Video created out of the crossections is much less valuable, nice pictures but it would require some creative hard work to re-create 3D model out of that versus original RAW data.
  15. I don't think the complete raw micro-CT scan is included on the DVD. Just pictures and analyses are mentioned...