Why does it create imprecision? In the real world we drill holes with a drill that is longer than the hole. The hole is exactly the same length as the material it goes through. On Fri, 7 Oct 2022 at 17:27, Bogdan Caramalac via Discuss < discuss@lists.openscad.org> wrote: > > > > ---------- Forwarded message ---------- > From: fxeconomist@yahoo.com > To: discuss@lists.openscad.org > Cc: > Bcc: > Date: Fri, 7 Oct 2022 16:26:14 +0000 > Subject: [OpenSCAD] something upsets me about difference() > > It upsets me for quite a while. > > Whenever I cut something, say with a cylinder, I always need to make it > longer than the cut hole. > > If I don’t, the hole is displayed on screen in a flipping on/off state, > while if I make it longer by one unit, the hole appears integrally cut. > > This creates an induced imprecision in most of the drawings. > > > > ---------- Forwarded message ---------- > From: Bogdan Caramalac via Discuss <discuss@lists.openscad.org> > To: discuss@lists.openscad.org > Cc: fxeconomist@yahoo.com > Bcc: > Date: Fri, 7 Oct 2022 16:26:14 +0000 > Subject: [OpenSCAD] something upsets me about difference() > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >

It is commonly called "z-fighting" (or "x" or "y") and is common amongst 3D tools, not just OpenSCAD. The problem is that with an "exact" cut, the result is a 0 thickness surface. But that doesn't mean the surface is gone, it is just 0-thickness. Most tools (even 3D slicers) can have issues with this. This, you cut a bit more (just one more unit, as you said) and the conundrum is solved. On Fri, Oct 7, 2022 at 11:29 AM nop head <nop.head@gmail.com> wrote: > Why does it create imprecision? In the real world we drill holes with a > drill that is longer than the hole. The hole is exactly the same length as > the material it goes through. > > On Fri, 7 Oct 2022 at 17:27, Bogdan Caramalac via Discuss < > discuss@lists.openscad.org> wrote: > >> >> >> >> ---------- Forwarded message ---------- >> From: fxeconomist@yahoo.com >> To: discuss@lists.openscad.org >> Cc: >> Bcc: >> Date: Fri, 7 Oct 2022 16:26:14 +0000 >> Subject: [OpenSCAD] something upsets me about difference() >> >> It upsets me for quite a while. >> >> Whenever I cut something, say with a cylinder, I always need to make it >> longer than the cut hole. >> >> If I don’t, the hole is displayed on screen in a flipping on/off state, >> while if I make it longer by one unit, the hole appears integrally cut. >> >> This creates an induced imprecision in most of the drawings. >> >> >> >> ---------- Forwarded message ---------- >> From: Bogdan Caramalac via Discuss <discuss@lists.openscad.org> >> To: discuss@lists.openscad.org >> Cc: fxeconomist@yahoo.com >> Bcc: >> Date: Fri, 7 Oct 2022 16:26:14 +0000 >> Subject: [OpenSCAD] something upsets me about difference() >> _______________________________________________ >> OpenSCAD mailing list >> To unsubscribe send an email to discuss-leave@lists.openscad.org >> > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >

I can cut more on the outer hole side, but if I have only N units to cut inside, does it actually cut N ? And what happens if on the outside is actually another object ? It’s not within the difference() declaration, it won’t cut from it, right ?