Moving each surface out by a certain amount is not very efficient for many cases. Consider cutting a rectangular pocket having small radius corners. The efficient approach would use a large cutter to clear most of the waste and a small cutter for the corners. Your suggestion would require that the entire perimeter be cut using a small cutter.
> -----Original Message----- > From: Chris Albertson [mailto:albertson.ch...@gmail.com] > Sent: Tuesday, July 24, 2018 8:45 PM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] CAD for LinuxCNC > > It is not clear if your method would work in the general case. "rest" > seems easy of doing a "waterline" type operate on a 3-axis mill. But what > about a 5-axis machine? > > I think the best way to program a rest tool path is to first transform the > part into a larger part thais is only roughed out. You might do this by > moving every surface out in the normal direction my some amount like 1mm. > The you make that part using a roughing cutter. Then swap cutters and > make the part as per the 3D model. I don't think you need simulation. > But you do need to be able to move the surface out in the direction of the > surface normals. > > On Tue, Jul 24, 2018 at 1:24 PM Roland Jollivet <roland.jolli...@gmail.com> > wrote: > > > On 24 July 2018 at 22:02, Sebastian Kuzminsky <seb.kuzmin...@gmail.com> > > wrote: > > > > > On Tue, Jul 24, 2018 at 1:45 PM Valerio Bellizzomi <vale...@selnet.org> > > > wrote: > > > > On Tue, 2018-07-24 at 21:27 +0200, Roland Jollivet wrote: > > > > > I had a quick look at PyCAM, and FreeCAD's Path Workbench. > > > > > > > > > > >From what I see, neither seem to do rest milling (rest machining), > > > which is > > > > > a limitation of most of the free packages and makes it pretty useless > > > for > > > > > multiple cutters unless you are extremely vigilant on what was not > > cut. > > > > > > > > > > Or do they do rest milling? > > > > > > > > I have no idea of what it is, but there is a feature request: > > > > > > > > https://github.com/SebKuzminsky/pycam/issues/120 > > > > > > I think "rest machining" refers to doing initial machining passes with > > > a large-diameter cutter, having the CAM keep track of the remaining > > > material that needs to be removed, and then doing finishing passes > > > with a smaller-diameter cutter to remove that remaining material. For > > > example, think of a large pocket with sharp corners, roughed out with > > > a large endmill and then finished with a small endmill. > > > > > > The feature request you linked above is different (and simpler): it's > > > just to do "normal" machining operations on *select* features in the > > > model, instead of applying the operations to *all* features of the > > > model. > > > > > > > Yes. When milling steel it's very easy to snap a 3mm cutter because the > > previous 6mm cutter couldn't go into a dip, and the path is using the final > > geometry as the reference model for the 3mm cutter. > > > > I've often wondered how hard it would be to program 'rest machining' > > I think stl format is fine for most hobbyists, and offers a simpler way of > > keeping track of a solid in software. > > > > A method I envisage is as follows; > > Say operations are chosen as follows; > > - first a 10mm roughing, then > > - 3mm finishing with 0.2mm remaining, then > > - 1mm final pass, 0mm remaining > > > > Once all the parameters are selected, the software creates a machining > > model in Reverse... > > First it takes the final .stl and adds on a 0.2mm layer, by computing > > triangles according to the path of the 1mm cutter parameters, then > > adds the 3mm passes, and so on until the full stock has been generated. > > Obviously now these operations are run in reverse again to create a forward > > Gcode file. > > > > Possible? > > > > ---------------------------------------------------------------------------- -- > > Check out the vibrant tech community on one of the world's most > > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > -- > > Chris Albertson > Redondo Beach, California > ---------------------------------------------------------------------------- -- > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
