Next time please give a full code example. If you do a negative and a positive offset() with the same parameter the result will be identity. I guess you want to have your slot object with rounded edges at the "original" size. Using offset() this is only possible, if you construct the square part smaller and the hole part larger by the chamfer value. $fn = 30; s = 40; round_chamfer=1; translate([0,-s/2,0]) slot(); translate([0,0,0]) offset(round_chamfer) slot(offs=round_chamfer); module slot(a = 12, b = 16, r = 4, offs = 0) { difference() { square([a-2*offs, b-2*offs] , center = true); hull() { circle(r+offs, center = true); translate([a, 0]) circle(r+offs, center = true); } } } -- View this message in context: http://forum.openscad.org/how-to-make-round-chamfer-at-2D-object-tp19714p19715.html Sent from the OpenSCAD mailing list archive at Nabble.com.

>If you do a negative and a positive offset() with the same parameter the result will be identity. No it will round the convex or concave corners (depending on the order) with a radius equal to the offset. I use it regularly. On 24 December 2016 at 12:08, Parkinbot <rudolf@parkinbot.com> wrote: > Next time please give a full code example. > If you do a negative and a positive offset() with the same parameter the > result will be identity. > > I guess you want to have your slot object with rounded edges at the > "original" size. Using offset() this is only possible, if you construct the > square part smaller and the hole part larger by the chamfer value. > > > > $fn = 30; > > s = 40; > round_chamfer=1; > translate([0,-s/2,0]) slot(); > translate([0,0,0]) > offset(round_chamfer) > slot(offs=round_chamfer); > > module slot(a = 12, b = 16, r = 4, offs = 0) > { > difference() > { > square([a-2*offs, b-2*offs] , center = true); > hull() > { > circle(r+offs, center = true); > translate([a, 0]) > circle(r+offs, center = true); > } > } > } > > > > > > -- > View this message in context: http://forum.openscad.org/how- > to-make-round-chamfer-at-2D-object-tp19714p19715.html > Sent from the OpenSCAD mailing list archive at Nabble.com. > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >

 Next time please give a full code example.
 If you do a negative and a positive offset() with the same
 parameter the
 result will be identity.

If either of you (nop head, Parkinbot) could provide a small example, I would appreciate it. On 12/24/2016 7:15 AM, nop head wrote: > >If you do a negative and a positive offset() with the same parameter > the result will be identity. > > No it will round the convex or concave corners (depending on the > order) with a radius equal to the offset. I use it regularly. > > On 24 December 2016 at 12:08, Parkinbot <rudolf@parkinbot.com > <mailto:rudolf@parkinbot.com>> wrote: > > Next time please give a full code example. > If you do a negative and a positive offset() with the same > parameter the > result will be identity. >

On 24. des. 2016 13:08, Parkinbot wrote: > I guess you want to have your slot object with rounded edges at the > "original" size. Using offset() this is only possible, if you construct the > square part smaller and the hole part larger by the chamfer value. Using your slot() you can do the following to get rounded corners of the original object, with original size and given radius: $fn = 30; rad = 1; offset(r=rad) offset(delta=-rad) slot(); Carsten Arnholm

$fn = 32; module shape() difference() { square(40, center = true); square(20, center = true); } color("red") offset(3) offset(-3) shape(); translate([50, 0, 0]) color("blue") offset(-3) offset(3) shape(); ​ On 24 December 2016 at 12:18, jon <jon@jonbondy.com> wrote: > If either of you (nop head, Parkinbot) could provide a small example, I > would appreciate it. > > On 12/24/2016 7:15 AM, nop head wrote: > > >If you do a negative and a positive offset() with the same parameter the > result will be identity. > > No it will round the convex or concave corners (depending on the order) > with a radius equal to the offset. I use it regularly. > > On 24 December 2016 at 12:08, Parkinbot <rudolf@parkinbot.com> wrote: > >> Next time please give a full code example. >> If you do a negative and a positive offset() with the same parameter the >> result will be identity. >> > > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > >

runsun, you are right. It is obviously not identity (only the initial example). So what do you do, if you want to have inner and outer edges rounded? -- View this message in context: http://forum.openscad.org/how-to-make-round-chamfer-at-2D-object-tp19714p19724.html Sent from the OpenSCAD mailing list archive at Nabble.com.

On 25. des. 2016 00:19, Parkinbot wrote: > So what do you do, if you want to have inner and outer edges > rounded? You apply both techniques at once. module rectangle_with_hole(a = 12, b = 16, th = 4) { difference() { square([a,b],center=true); square([a-2*th,b-2*th],center=true); } } $fn = 30; rad = 1.5; // causes outer loop rounding offset(r=rad) offset(r=-rad) // causes inner loop rounding offset(r=-rad) offset(r=rad) rectangle_with_hole(); Carsten Arnholm

Cool -- View this message in context: http://forum.openscad.org/how-to-make-round-chamfer-at-2D-object-tp19714p19732.html Sent from the OpenSCAD mailing list archive at Nabble.com.