Re: How to make "face plate insets" for cube+frustum combination Hello, (I have no real CAD/CAM experience and little OpenSCAD experience, so terminology is probably off. Sorry about the double-spaced paragraphs - I don't know how Google Mail treats return characters.) I have the following design for a piece of jewelry, which is a cube plus a frustum (with some other stuff taken out of the middle), into which I want to inset "face plates" on all sides that would be suitable for wire EDM manufacture. The plates will have Chinese characters on them, so die sink EDM might not be fine enough to carve them (?) The main body looks like this: [image: Frustum Cube.png] The plates for the cube sides are easy - just make more cubes, and subtract the bulk from the main cube. but how do I do the plates for the frustum? I want something like this sketch: [image: IMG_0460.jpg] With the vaguely-tesseract-looking thing being the inset plate. I'd prefer not to have to calculate the angles and offsets and everything with trig to construct it directly - it's complicated and introduces errors. (Yeah, if I knew how to use Fusion, this could probably be put together in about 15 minutes.) (*) I have another version with "out-set" characters ("bossed" rather than "em-bossed"?) on top of the faces of the cube and frustum, for which I have to calculate the frustum angle to rotate the extruded character: xAxisRotation = atan(frustumHeight / ((cubeSideLength-frustumTopWidth)/2)); (The translucent stuff is a cavity on the inside.) [image: Pendant Cube-Frustum Mockup.png] This for some reason introduces strange little bitty errors where one piece of an extruded letter (the bottom stroke of a "二" ("èr") character) doesn't *quite* reach the face of the frustum, so the resulting STP->BREP conversion in Fusion (to end up with an STP file) ends up with two components. So I have a small fudge factor to make sure the character intersectss the face. That design is a single piece and would be simpler to manufacture (one piece, by CNC and die-sink EDM.. But requires die-sink EDM. *Could* it be done with CNC? The smallest features of the characters are about 0.1 mm, and I doubt a CNC bit that thin is possible. Is there such as a "needle sink" EDM that's used to do very fine engravings? How *are* very fine details put on metal (engraved iPods, pens, rings, etc)? Thanks, Jim

If I understand your intent, you want to cut out a shape from the various faces of the shape. I would do it using the BOSL2 attachment features. No math required, and the code is pretty straight forward, I'd say. https://github.com/revarbat/BOSL2/wiki/Tutorial-Attachments https://github.com/revarbat/BOSL2 include<BOSL2/std.scad> cubesize = 40; topsize = 10; topheight = 20; diff("cut") cuboid(cubesize){ tags("cut") attach([RIGHT,FRONT,LEFT,BACK]) cyl(r=8,h=3); attach(TOP) prismoid([cubesize,cubesize],[topsize,topsize], topheight){ tags("cut") attach([RIGHT,LEFT,BACK]) cyl(r=8,h=3); color("red")attach(FRONT) atext("A",anchor=CENTER,h=2,size=15); } } On Fri, Nov 19, 2021 at 11:45 AM Jim Witte <jim.witte@gmail.com> wrote: > Re: How to make "face plate insets" for cube+frustum combination > Hello, > > (I have no real CAD/CAM experience and little OpenSCAD experience, so > terminology is probably off. Sorry about the double-spaced paragraphs - I > don't know how Google Mail treats return characters.) > > > I have the following design for a piece of jewelry, which is a cube plus > a frustum (with some other stuff taken out of the middle), into which I > want to inset "face plates" on all sides that would be suitable for wire > EDM manufacture. The plates will have Chinese characters on them, so die > sink EDM might not be fine enough to carve them (?) The main body looks > like this: > > [image: Frustum Cube.png] > > The plates for the cube sides are easy - just make more cubes, and > subtract the bulk from the main cube. but how do I do the plates for the > frustum? I want something like this sketch: > > [image: IMG_0460.jpg] > > With the vaguely-tesseract-looking thing being the inset plate. I'd > prefer not to have to calculate the angles and offsets and everything with > trig to construct it directly - it's complicated and introduces errors. > > > (Yeah, if I knew how to use Fusion, this could probably be put together in > about 15 minutes.) > > > (*) I have another version with "out-set" characters ("bossed" rather than > "em-bossed"?) on top of the faces of the cube and frustum, for which I have > to calculate the frustum angle to rotate the extruded character: > > > xAxisRotation = atan(frustumHeight / ((cubeSideLength-frustumTopWidth)/2)); > > (The translucent stuff is a cavity on the inside.) > > [image: Pendant Cube-Frustum Mockup.png] > > This for some reason introduces strange little bitty errors where one > piece of an extruded letter (the bottom stroke of a "二" ("èr") character) > doesn't *quite* reach the face of the frustum, so the resulting STP->BREP > conversion in Fusion (to end up with an STP file) ends up with two > components. So I have a small fudge factor to make sure the character > intersectss the face. > > > That design is a single piece and would be simpler to manufacture (one > piece, by CNC and die-sink EDM.. But requires die-sink EDM. *Could* it be > done with CNC? The smallest features of the characters are about 0.1 mm, > and I doubt a CNC bit that thin is possible. > > > Is there such as a "needle sink" EDM that's used to do very fine > engravings? How *are* very fine details put on metal (engraved iPods, > pens, rings, etc)? > > > Thanks, > Jim > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >