Thanks!
He's wanting to show a violin being carved in a couple minutes flat.
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| DXF file of a Violin top??? http://luthiersforum.com/forum/viewtopic.php?f=10106&t=13345 |
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| Author: | Don Williams [ Wed Aug 22, 2007 10:13 pm ] |
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Does anyone out there have a .dxf file of a violin top they would be willing to share? A guy who has helped me out tremendously with my cnc project is looking for one, so I told him I'd try to find one. Thanks! Don |
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| Author: | Bob Garrish [ Thu Aug 23, 2007 4:49 am ] |
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Did you try digging around on CNCZone? I'm too busy to look myself, but I'm pretty sure that some people have posted such things on there and you'd be able to find them with the search function. |
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| Author: | Don Williams [ Thu Aug 23, 2007 10:07 pm ] |
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Bob, Actually, it was a Zoner who was looking for it! I'll poke around some more there. Actually, even if someone has a print, Craig Sullivan will scan it and turn it into a dxf tile for me. |
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| Author: | Mike Mahar [ Fri Aug 24, 2007 12:17 am ] |
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I know very little about CAD. Is a DXF file a 3D model or is it just the outline? Violin tops are unique personalities. When you buy a plan it is always for a particular instrument. So, the question is which violin does your friend want. Our good friend Al has done some interesting work on the arch of the violin. To make a 3D model you could scan in a simple outline of top and then use the mathematical models to generate the arch. This would be a generic violin top which would need to tuned once carved. The lateral arch is a curtate cycloid which is the curve you get if you were to tie a Sharpie to the valve stem of your tire and then drive right next to a wall. The longitudinal arch is a simple spline or "bent stick" curve. The curve of the inside of the top plate is very close to a constant thickness. I don't remember how thick it is, however. |
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| Author: | Parser [ Fri Aug 24, 2007 6:18 am ] |
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A DXF is a "generic" CAD format that AutoDesk came up with (AutoDesk is the company that makes AutoCAD). It literally translates to "Drawing Exchange Format" and is a format that is "open source", meaning that it is a public format and that all the CAD programmers are able to read and interpret files of this format (as opposed to proprietary formats like MasterCAM). A DXF can contain 3D entities such as surfaces, but I believe that IGES/.igs (which I think translates to International Graphics Exchange Format) files are more standard for exchanging 3D data. DXF is more commonly used to transmit 2D cad data, or 3D wireframes. If you are playing with 3D surfaces I'd recommend using IGS. You should be able to express most curves as a spline. Splines are very versatile curves and can be used to approximate more mathematically based curves as well as more organic curves. I'll have to check out that curtate cycloid...haven't played with any of those yet. Back in my past life, I used to model involute curves using splines (these are the curves that define the curve on the edges of gear teeth). They came out within a couple thou, which was good enough for what we were doing. |
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| Author: | Don Williams [ Fri Aug 24, 2007 8:27 am ] |
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He isn't particular about which violin, just "a" violin. This is for a demonstration he is doing for his local guild. |
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| Author: | Parser [ Sat Aug 25, 2007 2:40 am ] |
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I'll fake one up for him...I'll post the results & a link the file once it's finished. |
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| Author: | Don Williams [ Sat Aug 25, 2007 8:24 am ] |
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Thanks! He's wanting to show a violin being carved in a couple minutes flat.
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| Author: | Bob Garrish [ Sun Aug 26, 2007 7:25 am ] |
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I hope he's got one fast spindle, like a 50K RPM that can handle a 1" ball, unless he counts a scallopy mess as a violin. The feed rate would be disturbing. |
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| Author: | Don Williams [ Sun Aug 26, 2007 7:42 am ] |
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Yeah, I think he was exagerating a tad, but I know his machine really flys with the G203V's and the G-100. I'm guessing he make several passes reasonably quick, and slow down for a final finish pass. |
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