On Tuesday 07 August 2018 13:41:18 Chris Albertson wrote: > Yes, that is the method I would use: Create the full scroll then use > that as a "tool" to > remove material from a black jaw model. You could never get it to > match up otherwise. > Just last night I needed to make a lid for a box and wanted an > interlocking goose. So > I make the lid about 10 mm to tall and use the box to cut off the > excess. > > But there is one problem with the technique, especially when making > metal parts, you need > some clearance. This is why there is an "offset" tool to reduce the > size of the part by a few > 0.01 mm or whatever you need. > This brings up an argument against doing it aligned with an axis but s/b aligned at 45 degrees so there is never an axis direction reversal while the tool is within the material. Its been my experience, with the quality of machine and ball screws I can afford, that one can never get a completely invisible axis reversal although I do have bearings seated in such carvings, carved on a micro-mill after very carefully setting the XY axis's backlash. Sure, lay it out and generate the code aligned with an axis just because its easier that way, but mount the jaw holding vise at nominally 45 degrees, measure its angle with a touch probe and sci calculator, and rotate the co-ord map to match. That will move any direction reversals to outside of the workpiece. Voila! Perfect curves w/o any backlash artifacts. > > But is you mill good enough to cut a spiral? Getting the g-code is > the easy part. > > > If you draw the spiral in cad, then choose a section of maximum > > radius, and minimum radius that a jaw 'tooth' will traverse. > > > > Now superimpose those two profiles and lop off any excess, keeping > > only the intersecting area. > > Repeat for all jaw 'teeth' > > Then hand code the segments..
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