On Mon, 12 Sep 2011 13:18:40 -0700, you wrote: >I would like to mill some 3D surfaces (violin plates) but I need a means >to go from a paper plan to g-code. I have Synergy with 3D, but I would >prefer to use a free and open solution. Heeks looks promising but >doesn't look like it is ready for general consumption yet. It looks to >me like I should be able to use a few key points such as a set of 2D >curve end and center points plus some sort of curve fitting algorithm to >come up with the intermediate points on the curve. I looked at Bezier >and NURBS curves, but from my brief look at them, it looks like the >curves only go through the known end points and not through known way >points. Is there a curve type I should look at? Or, even better, is some >one machining 3D curves appropriate for instrument making or boat hulls >and would like to share how it is generally done?
I've done a couple of F5 type mandolin fronts and backs - they are very similar in form to violins. Thickish near the edges going thinner and then back to thick again near the center. The shape is very complex as an F5 is not symmetrical. Unfortunately, none of the software I use is free. The drawings were scanned into Rhino 4 and curves generated using a combination of contour type lines in top view and a series of cross sections provided in the original plans. A surface can then be lofted using these curves then refined as required. Although this is a ships hull tutorial it will give you some idea of how it's done http://www.youtube.com/watch?v=3XkdIsleAqY Rhino also has some really good surface analysis tools like Zebra which renders black and white stripes on the surface, manipulating the view gives you a really good idea of what the curves of the surface look like and easily show low or high spots which may need some work. It takes a lot of time and effort to get the shapes just right, a few days in my case. Exporting the solid to CAM (FeatureCam) an creating the tool paths is a couple of hours work at most. Rough machining is quick using a 1/2" round carbide router bit with 40% step over, finishing to an acceptable finish for final sanding takes longer, I used a 1/4 round bit, initially with 10% step over, but I increased that to 20% as I found sanding was quicker than routing, even though the router was running at 140 ipm ;) Steve Blackmore -- ------------------------------------------------------------------------------ BlackBerry® DevCon Americas, Oct. 18-20, San Francisco, CA Learn about the latest advances in developing for the BlackBerry® mobile platform with sessions, labs & more. See new tools and technologies. Register for BlackBerry® DevCon today! http://p.sf.net/sfu/rim-devcon-copy1 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
