Also note that a real nut is also smaller across corners because it too doesn't have infinitely sharp edges. -- View this message in context: http://forum.openscad.org/cylinder-radius-problem-tp11703p11713.html Sent from the OpenSCAD mailing list archive at Nabble.com.

Aware of the limitations. -- View this message in context: http://forum.openscad.org/cylinder-radius-problem-tp11703p11714.html Sent from the OpenSCAD mailing list archive at Nabble.com.

On Sun, Feb 22, 2015 at 12:47 PM, nophead [via OpenSCAD] < ml-node+s1091067n11710h90@n5.nabble.com> wrote: A 3D printed part will always be smaller across corners than the STL file > it is printed from because you get a radiused corner rather than an > infinitely sharp one. The corner radius depends on the filament width and > how much the plastic is stretched. > > Understood, but the flats are WAY small. So on the physical nut, I measure 8.5mm across the flats. Radius is then 4.25 Cos(30) is 0.866 so I would get 4.9 Ok, I'll give that a try. Can I use the cosine function in OpenScad? -- View this message in context: http://forum.openscad.org/cylinder-radius-problem-tp11703p11715.html Sent from the OpenSCAD mailing list archive at Nabble.com.

Yes it is cos(30) in OpenScad. On 22 February 2015 at 20:01, dbvanhorn <kc6ete@gmail.com> wrote: > > > On Sun, Feb 22, 2015 at 12:47 PM, nophead [via OpenSCAD] <[hidden email] > <http:///user/SendEmail.jtp?type=node&node=11715&i=0>> wrote: > > A 3D printed part will always be smaller across corners than the STL file >> it is printed from because you get a radiused corner rather than an >> infinitely sharp one. The corner radius depends on the filament width and >> how much the plastic is stretched. >> >> > Understood, but the flats are WAY small. > > So on the physical nut, I measure 8.5mm across the flats. > Radius is then 4.25 > Cos(30) is 0.866 so I would get 4.9 > > Ok, I'll give that a try. > > Can I use the cosine function in OpenScad? > > > > > ------------------------------ > View this message in context: Re: cylinder radius problem > <http://forum.openscad.org/cylinder-radius-problem-tp11703p11715.html> > Sent from the OpenSCAD mailing list archive <http://forum.openscad.org/> > at Nabble.com. > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org > >

Ok, here's what I ended up with: Nut_Flats = 8.50; // Measure across the flats. Nut_Slack = 0.2; Flats_Rad = Nut_Flats/2; Nut_Rad = ((Flats_Rad / cos(30)) + Nut_Slack); // Correction factor to allow a little wiggle.

Cool. Layer 1 is down, and a real nut sits nicely in the recess. Thanks folks! I'm liking this program a lot. I've use PovRay for years for modeling light pipes and such, and this is very similar. -- View this message in context: http://forum.openscad.org/cylinder-radius-problem-tp11703p11718.html Sent from the OpenSCAD mailing list archive at Nabble.com.