Waterline Status
August 27, 2007 · Filed Under MeshCAM Development
After the last posting it took about a hour to move the new waterline code from the test command in the photo into the main machining dialog. It worked pretty well until I started playing with the machining angle- I found the parallel and waterline were not consistent near the threshold angle. I’ve tried a number of approaches and am finally closing in on a good solution. My current approach may have more overlap between the regions but with fewer retracts and a much smoother finished part because I’m trying to maximize the path length rather than stopping a path when a surface angle threshold is passed- even if it’s only exceeded for a short span.
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One Response to “Waterline Status”
Robert, that sounds like a winning strategy to me. I have come to the conclusion that keeping the tool in the cut is actually more important than uber-triangulation of the part. Especially on flexible machines like the Sherline, and especially when using long, flexible cutters. I think that overlap is no problem as long as the toolpath flows well.
I’ve been experimenting pretty extensively with 6628 over the past several days (trying to determine the tradeoff between triangulation and surface quality), and my main limitation right now in documenting the results is in trying to photograph the surface of machined clear acrylic–I might need to repeat the machining in aluminum, which means using coolant which will mean Randy standing duty with string mop since my machine base leaks… I don’t know how other programs set their STL parameters, but with Solidworks and my particular geometry I find that .002″ deviation and 15 degree angle (5128 faces on my test STL) gives visible faceting, while .0003″ deviation and 1.5 degree angle (137k faces) and .0003″ deviation and 0.5 degree angle (1.47M faces) don’t give a visible difference with a .005″ stepover with a .250″ ballmill, X passes only. But I am stymied in trying X-Y passes because the Z axis is dropping by .020″ or so between the X and Y passes, and I haven’t figured the cause. Of course, in my real machining I usually use a more reasonable stepover of .002″ and do a semi-finishing pass leaving a uniform .005″ “shell” over the final shape to remove with the finishing pass…
I have had good success in overcoming the little pop-up-to-stock-top problem I sent you screenshots of–it is fairly simple with search-and-replace together with some repetitive hand editing to rectify the toolpath, which actually works very well.
Looking forward to trying the next version (and will upload photos of the current testing to the Yahoo group as soon as I get the lighting sorted out)
Randy