Greetings all; I have another of my wild hair ideas, and want to make a bearing seat that will hold a 4" diameter plastic bearing nominally 9/32" out of round. IOW, how do I nake a true, mathematically accurate eccentric in openscad? Thanks everybody. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene>

Can you give a bit more detail? What hapens when you use scaling? Do you have any code to show? On 2021-04-27 9:50 p.m., Gene Heskett wrote: > Greetings all; > > I have another of my wild hair ideas, and want to make a bearing seat > that will hold a 4" diameter plastic bearing nominally 9/32" out of > round. IOW, how do I nake a true, mathematically accurate eccentric in > openscad? > > Thanks everybody. > > Cheers, Gene Heskett -- Ron Wheeler Artifact Software 438-345-3369 rwheeler@artifact-software.com

Hi, If it is an eccentric you want, as used in, say, Stephenson's valve gear, then in your example, it will have a throw of 9/16 inch.  so, make a vertical stubby cylinder to hold your bearing (if you need to insert the bearing) and translate it 9/32 inch in the x direction, say. The centre that you need for the axle/whatever will be at the origin, so put the axle there. On 28/04/2021 02:50, Gene Heskett wrote: > Greetings all; > > I have another of my wild hair ideas, and want to make a bearing seat > that will hold a 4" diameter plastic bearing nominally 9/32" out of > round. IOW, how do I nake a true, mathematically accurate eccentric in > openscad? > > Thanks everybody. > > Cheers, Gene Heskett