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How hard is it to do a just slighty eccentric circle in openscad?

GH
Gene Heskett
Wed, Apr 28, 2021 1:50 AM

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.

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>
RW
Ron Wheeler
Wed, Apr 28, 2021 2:40 AM

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

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
RW
Ray West
Wed, Apr 28, 2021 11:13 AM

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

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