"For Dummies" question on OpenSCAD using rotate_extrude

[choco 0]

Hi all,

Now that I'm getting regular success printing designs from Thingiverse I'm trying to create my first "thing". It's a fix for a floor lamp that my kids have knocked over one too many times. I've used calipers to measure the internal and external lamp-part dimensions and am using OpenSCAD for the first time. I've got the 2D profile of it right, but I now need to use rotate_extrude around the z axis to get the actual 3D shape. Thing is, it just draws the 2D profile. It doesn't give me any error message.

Would someone mind have a quick glance at my code and tell me where I'm going wrong?

Thanks!

Choco.

 

module lampfix2d();

{

extra_w=2;

top_w=2.8;

bottom_w=top_w+27.3-26.9;//bottom_external - top_external

height=5;

translate([-8.06,0,0])

polygon( [ [0,0],[0,height+extra_w],[-top_w-2*extra_w,height+extra_w],[-bottom_w-2*extra_w,0],[-bottom_w-extra_w,0 ],[-top_w-extra_w,height ],[-extra_w,height],[-extra_w,0 ] ] );

}

rotate_extrude(convexity=10) lampfix2d();

 

[kokr 0]

Hello choco,

I changed the code as following:

extra_w=2;

top_w=2.8;

bottom_w=top_w+27.3-26.9; //bottom_external - top_external

height=5;

module lampfix2d()

{

translate([8.06,0,0])

polygon( points = [ [0, 0],

[0, height+extra_w],

[-top_w -2*extra_w, height+extra_w],

[-bottom_w-2*extra_w, 0],

[-bottom_w -extra_w, 0 ],

[-top_w -extra_w, height ],

[ -extra_w, height ],

[ -extra_w, 0 ] ],

paths= [ [0,1,2,3,4,5,6,7]]);

}

rotate_extrude(convexity=10)

lampfix2d();

because of the ; after the module statement, openscad "sees" this as an empty command.

Further I think Openscad does not like a negative value for the translate in the rotate extrude.

Regards,

Kok

 

[choco 0]

Kok,

Thanks!

You were absolutely right about the negative value in the translate function, but it seems it's not the translate function itself that has a problem but rotate_extrude, which seems to have issues with an object in the negative quadrant.

Unfortunately, the negative value was necessary the way I'd laid it out. So instead, I re-did the polygon to have it all on the positive side of the x axis and now it works.

Thanks also for the example of neater coding.

Choco.