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Everything posted by MikeC

  1. After finishing the back plate I wanted to try and analyze it with Audacity. I don't know if I'm doing it right. Does this look like a normal plot from tapping a plate?
  2. ok I misunderstood. I thought you meant iron nails. Actually I think most? makers do still have the pins showing? I have them on mine. Based on what I've read they were necessary as part of the baroque building method where the neck was nailed on the ribs first with iron nails then these wood pins were used as sort of a pivot point to help align the ribs with the plate. I think it was an article written by Roger Hargrave where I read that. For the most part I think they are still used to help position the plates for glue up. It's a quick way to make sure pates and ribs are lined up when gluing. When using hide glue you don't have much working time so you have to get things positioned and clamped quickly. Now I'm wondering who does not use them and why not?
  3. In those two pictures, those aren't nails they are wood pins used to locate the plates on to the rib garland while gluing. After the plate is glued the wood pin is cut off flush. In a Stradivari violin the pufling typically goes half way over the pin so only half the pin is showing. What I find interesting is the tail piece saddle. That's a modern saddle but under it remains a part of the original saddle. I wonder if that original part is glued on the surface of the rib or inset into it.
  4. I was assuming the accuracy of the image on platetuning.org which shows the average of multiple Strad backs. Maybe you could call that circular but it appears to extend farther along the long axis than a circle would. Also on the CT scan of the Titian I see what appears to be a somewhat linear feature. No I haven't measured any in person obviously. Of course this is just an average of multiple instruments so there are lots of variation among individual plates. My guess is that he had some standard pattern and adjusted each plate according to it's characteristics.
  5. One other thought on Strad vs. the others. Strad's thickness in the back plate is not circular, it's more longitudinal. If the others used the pin hole as a fixed compass point for graduating the plates then you would expect to see somewhat circular pattern in the thickness and that seems to be the case in the thickness maps that I've seen of DelG. Could that be why Strad did not have the hole while others did? Who knows... just one possible explanation, not necessarliy the right one. A problem with that idea is that the pin hole seems to be farther towards the neck end than the center of thickness on DelG violins.
  6. I wonder what kind of bit would have been used back then. Twist bits and gimlets were not invented until the 1800s. Prior to that I guess they would have had some type of spade bit or spoon bit. It's easy enough to put a mark on a bit and stop at the mark. I have a drill press but in my current build I just put a piece of tape on the bit and hand drilled it in the C bout. I don't drill holes all over the plate, just one in the center for a guide in that area.
  7. I don't see an image. looks like a broken link.
  8. Yes I would like to know how you got this also. It looks like Davide's linoxin. I need a fast way to get linoxin since I don't have five years to wait for it form naturally. If you think its ruined send to me, I'll find a use for it!
  9. Here's the latest progress. Hollowing out the inside. It's still a bit thicker than I want so there is more thinning to do. From a previous thread showing contour lines it looked Peanutty and there was a flat area in the lower bout. Then I realized I needed to redo the long arch and after that and reshaping the arching it's looking much better. Excuse the geometry at the bottom. I was just doing that to make sure some lines where perpendicular to the center line.
  10. I don't know how many are visible from the outside. Someone can correct me but I think all the Amati and Del Gesu have it. Strad does not have it. Makes you wonder in what ways Strad was doing things differently from the other makers at the time.
  11. I have a brace and bit. It's not all that primitive. I think they were quite capable of drilling a hole to any depth they wanted to.
  12. The problem I see with using a hole all the way through the plate for a guide to thickness is that it's not necessary. If you know how thick the plate should be at a certain point then you drill a hole to stop at that thickness. That way it doesn't risk going all the way through the plate and show on the outside. Some modern makers do that. Drill holes all over the inside stopping at a correct depth.
  13. is that piece of metal a scraper blade?
  14. Thirty plus years ago I acquired a whole pig hide with the idea of doing some leather work but never did. Finally I found a use for it. Lining the plate cradle so the outside of my plate wont get scratched while working on the inside. I still have most of the hide left. Anyone want to make a football? (American football, not soccer). Also I started hollowing the inside of the plate following D.Sora's videos. Four mm channel in the widest parts of the bouts. Five mm in the corners and six mm in the center. Drill a center hole to a plate thickness of 6mm as a guide while carving. Then remove the wood between the channels. Once that's done reduce it to final thickness with thumb planes. After working on the upper and lower bouts I started gouging with the grain in the center thinking that would remove more wood more quickly. One side worked well but the other side wanted to splinter in both directions. That's curly maple for you. One interesting thing I noticed is by doing it that way you start to get sort of a hexagon pattern forming in the middle which reminded me of the 'average of 48 Strad backs' from platetuning.org. Things that make you go hmmmm....
  15. I had the bright idea of planing along contour lines thinking this would produce a good arch profile vs. the usual cross arch thing. Results are ok. Also here's the bee stings. Those are ok too but need some improvement next time. One of them I'm not going to show. It needs fixing with black mastic so I'll show a before and after pic when it's done.
  16. That could be since the back has the obvious thickness graduation and the belly is 'almost' uniform thickness.
  17. You're getting old! LOL
  18. I would not agree with that if your goal is to build using the same methods that they used. It might be useful to know what they were doing and why they were doing it that way. Was the stick made by Cozio or was it made by Amati and Cozio just wrote on it? Obviously modern instruments are good and the end product is all that matters and if you built exactly as the old masters did then we would be making baroque instruments but still I would like to build using as much of the old methods as possible. I cheat and use modern tools, band saw, drill press but as far as graduation and arching I would certainly like to know what they had in mind back then.
  19. Another mystery is why the hole is only on the back, not the belly? Any theories?
  20. Would anyone care to guess what the mysterious white precipitate is on the inside of the F holes?
  21. You have no problem with glue ghosts? Or do you put in the purfling before gouging out the recurve area? That's my concern. I went ahead and used the conventional hide glue tonight. There was squeeze out.
  22. That's good to know, thanks! If I don't like the casein test results I'll just do it the normal way.
  23. Thanks! Once the purfling is glued in I'll still have some arching to do to get the contours right. Then I'll tackle the inside. I tried doing inside first on some poplar test plates but the technique didn't seem to work well for me so I'm doing the usual outside first method. Hopefully I can get all that done during the coming week and post some more pics.
  24. That looks good David thanks for the picture.
  25. Thank you, yes when I enlarge the image I see the cross lines are a false artifact from the xray. One line goes across the treble F hole. This is where I read about Stainer having multiple pin holes. Sorry this has strayed away from the original rib height discussion.