Posted by chris33
 urgent answer March 07, 2013 06:52PM Registered: 10 years ago Posts: 973
In open scad does the r1.8 translate to a 3.6mm cos I want to make the hole too 4.1mm which I was going to put this instead r2.05, am I incorrect cheers

Edited 1 time(s). Last edit at 03/07/2013 07:12PM by chris33.
 Re: urgent answer March 07, 2013 08:27PM Registered: 12 years ago Posts: 1,797
rad is 1/2 the diameter. so to go by diameter of circle for a cylinder
do this
tall=10;
size_in_diameter=4.1;

cylinder(r1=size_in_diameter/2,r2=size_in_diameter/2,h=tall,center=true);

if this does not answer your question, then please let us know. Someone will be more than willing to help on this forum.
 Re: urgent answer March 08, 2013 03:26PM Registered: 12 years ago Posts: 486
You can specify the number of facets on the "circle" that makes the hole too (using the \$fn=5 argument for example). If you have too many facets, the extruder may move slowly around the circle and ooze more plastic than intended making the hole smaller than intended. If you specify fewer facets, the hole will be smaller because the hole's vertices will be at the specified radius and the edges will be chords of the circle that make the circle smaller. You can make the chords tangents of the desired circle by dividing the radius by cos(180/number of facets). Also nophead's polyholes blog is a good read.

Edited 1 time(s). Last edit at 03/08/2013 03:29PM by Greg Frost.
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