Best way to draw a funnel

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Best way to draw a funnel

simon_w
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Hello, first-off I'm fairly new to openscad.

I'd like to draw a funnel with a smooth, e.g. arc, transition between the cone and the pipe.  What would be the best way to code this?

Thanks
Simon
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Re: Best way to draw a funnel

laird
That's a little tricky. I guess you could make a donut shape, then a cone tangent to the surface going up, and a cylinder tangent to the surface going down. Do that twice with different sizes by the thickness, and difference them.
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Re: Best way to draw a funnel

MichaelAtOz
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In reply to this post by simon_w
BTW your post is still flagged as "This post has NOT been accepted by the mailing list yet", you may want to check your registration.
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Re: Best way to draw a funnel

MichaelAtOz
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In reply to this post by simon_w
I'd have a look at rotate_extrude, generate the shape, then spin it around the axis to complete the funnel.

Simple example with a straight line:

rotate_extrude()
  translate([2,0]) // need to ensure it is all in the X+ quadent, also makes the hole.
    rotate(45)
      square([25,1]);

Then workout a curvey shape; a little harder.
Admin - email* me if you need anything,
or if I've done something stupid...
* click on my MichaelAtOz label, there is a link to email me.

Unless specifically shown otherwise above, my contribution is in the Public Domain; to the extent possible under law, I have waived all copyright and related or neighbouring rights to this work.
Obviously inclusion of works of previous authors is not included in the above.


The TPP is no simple “trade agreement.” Fight it! http://www.ourfairdeal.org/ time is running out!
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Re: Best way to draw a funnel

nophead
In reply to this post by simon_w
The best way to get tangents is with hull().

bowl = 50;
bowl_r = 50;
stem = 60;
stem_r = 5;
neck_r = 10;
thickness = 2;

curve_r = 10;

$fa = 5;
$fs = 0.1;
eps = 0.01;

module profile() {
        hull() {
                translate([stem_r, 0])
                        square([thickness, eps]);

                translate([neck_r + curve_r, stem])
                        circle(r = curve_r);
               
                translate([bowl_r, stem + bowl - eps])
                        square([thickness, eps]);
        }
}

rotate_extrude()
        difference() {
                profile();
                translate([thickness, 0])
                        profile();
        }

funnel
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Re: Best way to draw a funnel

simon_w
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Great, thanks for all your replies.  I'll tease apart the instructions to figure out exactly how its working.

I was pretty sure I'd tried to subscribe but didn't get the promised email.  Have tried again.

Cheers
Simon