I was trying to make a coin for a friend to 3D print with a bossing on top. I noticed that the coin or solid cylinder has a rough hexagonal shape to it. How do I get a smooth round texture instead of the hex looking couture? I also notice that round 3D models I modify in tinkercad then export to STL also have a hexagonal surface after being exported, when they there originally round without any noticeable hexigonalness. What's going on here? How do I fix this problem? Could someone maybe provide some simple example code? -- Sent from: http://forum.openscad.org/

STL files only contain triangular facets so you can't have a true arc, only a faceted approximation. Similarly OpenSCAD represents all shapes with a boundary mesh made of polygonal facets. You can have as many facets as you want by setting $fn, you are not limited to octogons. Higher values of $fn will slow down OpenSCAD. You can also specify the minimum angle $fa and the minimum edge length with $fs. This allows the number of edges to be set adaptively according to how big the circle is. For 3D printing I set $fa to 6 and $fa to half the extrusion width. That gives 60 sides for large circles (best to make it a multiple of four). Smaller circles hit the $fa limit and have less sides. On 31 August 2018 at 05:49, FourthDr <who_doctor@hotmail.com> wrote: > I was trying to make a coin for a friend to 3D print with a bossing on > top. I > noticed that the coin or solid cylinder has a rough hexagonal shape to it. > How do I get a smooth round texture instead of the hex looking couture? I > also notice that round 3D models I modify in tinkercad then export to STL > also have a hexagonal surface after being exported, when they there > originally round without any noticeable hexigonalness. What's going on > here? > How do I fix this problem? Could someone maybe provide some simple example > code? > > > > -- > Sent from: http://forum.openscad.org/ > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >

nop head did you mean? " For 3D printing I set $fa to 6 and $fs to half the extrusion width. That gives 60 sides for large circles (best to make it a multiple of four). Smaller circles hit the $fs limit and have less sides" On Fri, Aug 31, 2018 at 3:44 AM nop head <nop.head@gmail.com> wrote: > STL files only contain triangular facets so you can't have a true arc, > only a faceted approximation. > > Similarly OpenSCAD represents all shapes with a boundary mesh made of > polygonal facets. > > You can have as many facets as you want by setting $fn, you are not > limited to octogons. Higher values of $fn will slow down OpenSCAD. > > You can also specify the minimum angle $fa and the minimum edge length > with $fs. This allows the number of edges to be set adaptively according to > how big the circle is. > > For 3D printing I set $fa to 6 and $fa to half the extrusion width. That > gives 60 sides for large circles (best to make it a multiple of four). > Smaller circles hit the $fa limit and have less sides. > > On 31 August 2018 at 05:49, FourthDr <who_doctor@hotmail.com> wrote: > >> I was trying to make a coin for a friend to 3D print with a bossing on >> top. I >> noticed that the coin or solid cylinder has a rough hexagonal shape to it. >> How do I get a smooth round texture instead of the hex looking couture? I >> also notice that round 3D models I modify in tinkercad then export to STL >> also have a hexagonal surface after being exported, when they there >> originally round without any noticeable hexigonalness. What's going on >> here? >> How do I fix this problem? Could someone maybe provide some simple example >> code? >> >> >> >> -- >> Sent from: http://forum.openscad.org/ >> >> _______________________________________________ >> OpenSCAD mailing list >> Discuss@lists.openscad.org >> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >> > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >

Yes, sorry, typos that I thought I had already corrected before pressing send. On 31 August 2018 at 09:03, Mark Peeters <peetersmarkg@gmail.com> wrote: > nop head did you mean? " For 3D printing I set $fa to 6 and $fs to half > the extrusion width. That gives 60 sides for large circles (best to make it > a multiple of four). Smaller circles hit the $fs limit and have less sides" > > On Fri, Aug 31, 2018 at 3:44 AM nop head <nop.head@gmail.com> wrote: > >> STL files only contain triangular facets so you can't have a true arc, >> only a faceted approximation. >> >> Similarly OpenSCAD represents all shapes with a boundary mesh made of >> polygonal facets. >> >> You can have as many facets as you want by setting $fn, you are not >> limited to octogons. Higher values of $fn will slow down OpenSCAD. >> >> You can also specify the minimum angle $fa and the minimum edge length >> with $fs. This allows the number of edges to be set adaptively according to >> how big the circle is. >> >> For 3D printing I set $fa to 6 and $fa to half the extrusion width. That >> gives 60 sides for large circles (best to make it a multiple of four). >> Smaller circles hit the $fa limit and have less sides. >> >> On 31 August 2018 at 05:49, FourthDr <who_doctor@hotmail.com> wrote: >> >>> I was trying to make a coin for a friend to 3D print with a bossing on >>> top. I >>> noticed that the coin or solid cylinder has a rough hexagonal shape to >>> it. >>> How do I get a smooth round texture instead of the hex looking couture? I >>> also notice that round 3D models I modify in tinkercad then export to STL >>> also have a hexagonal surface after being exported, when they there >>> originally round without any noticeable hexigonalness. What's going on >>> here? >>> How do I fix this problem? Could someone maybe provide some simple >>> example >>> code? >>> >>> >>> >>> -- >>> Sent from: http://forum.openscad.org/ >>> >>> _______________________________________________ >>> OpenSCAD mailing list >>> Discuss@lists.openscad.org >>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>> >> >> _______________________________________________ >> OpenSCAD mailing list >> Discuss@lists.openscad.org >> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >> > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > >

Thanks Nophead for the reply. In a related question, since I am making a model from scratch I need to know what units of measure are being used. I see a scale in increments of 10. But is that inches or mm? Or something else? I need to know how big the object is going to be and that it is the correct size. -- Sent from: http://forum.openscad.org/

On 2018-09-01 10:04, FourthDr wrote: > Thanks Nophead for the reply. In a related question, since I am making > a > model from scratch I need to know what units of measure are being used. > I > see a scale in increments of 10. But is that inches or mm? Or something > else? I need to know how big the object is going to be and that it is > the > correct size. The models are unit-less. However, in 3d printing a common convention is to use mm. If you prefer to work in other units, you can scale the final result to mm easily. Carsten Arnholm

Export to STL seems to be in mm. But I didn't set any units. -- Sent from: http://forum.openscad.org/

STL is unit-less also. It is the slicer in a 3D printing chain that decides 1 unit is 1mm. On 1 September 2018 at 09:30, FourthDr <who_doctor@hotmail.com> wrote: > Export to STL seems to be in mm. But I didn't set any units. > > > > -- > Sent from: http://forum.openscad.org/ > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >

.STL in mm is just a very happy coincidence, or someone's very good anticipation for an important technology. Thanks folks!! Cheers, RobW On 1 September 2018 7:00:33 pm AEST, nop head <nop.head@gmail.com> wrote: >STL is unit-less also. It is the slicer in a 3D printing chain that >decides >1 unit is 1mm. > >On 1 September 2018 at 09:30, FourthDr <who_doctor@hotmail.com> wrote: > >> Export to STL seems to be in mm. But I didn't set any units. >> >> >> >> -- >> Sent from: http://forum.openscad.org/ >> >> _______________________________________________ >> OpenSCAD mailing list >> Discuss@lists.openscad.org >> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >>