Fwd: Re: Adding an angle / angle profile to openscad barbed object
exactly as I suggested, b4. Guessing from most of the stuff on
thingiverse, it's all generic, if it looks right, then it is right. For
this fitting. If I was the OP and wanted to make this thing, for all
practical purposes, the simple calculation I suggested would do. Even
print it as is and file off the sharp edges. If the angles need to be
more precise, then easy enough to calculate the value by using basic
sin/cos/tan equations. No need to reinvent a method, or use any outside
libraries/whatever, although nothing to stop anyone if they so wish. Of
course, if the OP does not know much about openscad, but wanted to
learn, then maybe a dialogue could be established. I guess such a guy
would have no idea what I originally implied, and is looking for a plug
and play solution. These days, generally lots of cut and paste in all
software development, and little fundamental studying. But if either
method gets the desired result, is one right and the other wrong?
(a couple of things for blokes to be aware of as you get older - 1) your
prostate, 2) becoming more right wing, and hence more right! )
On 19/08/2021 11:48, Michael Möller wrote:
Knowing the precision of the average 3d printer, and guessing this is
to fit a flexible hose pipe, a simple linear interpolation of the two
known values is probably enough.
Besides, using the "known values" is still trigonometry, even if you
do not use sin() :-) ☺
Msquare
tor. 19. aug. 2021 12.26 skrev Adrian Mariano <avm4@cornell.edu
mailto:avm4@cornell.edu>:
Jordan,
He wants the back angle on each barb to be different, 45 on one,
50 on another, and 60 on the third one. I don't know if the
length of each barb is required to stay the same or not. I
assumed they did, which means there's also a little flat area
behind each barb that varies in size depending on what that angle
was. If you special case the angles you can avoid explicit use of
trig with 45 and 60 deg angles (because you know the trig function
values for those angles), but not with 50---but if you want a
clean general solution you will need to use trig.
On Wed, Aug 18, 2021 at 11:34 PM Jordan Brown
<openscad@jordan.maileater.net
<mailto:openscad@jordan.maileater.net>> wrote:
On 8/18/2021 7:28 PM, Father Horton wrote:
Or you could trace the outline and rotate_extrude it.
That's what I would think of, where "trace" means "construct a
single polygon".
I wouldn't have thought of using trig at all, because I would
have thought that the inputs would be the dimensions of the
barbs, not the angles. (But the cylinder solution wouldn't
need trig either, since again you wouldn't have angles as inputs.)
Here's what I would come up with. Generalizing to a
double-ended barbed thing is left as an exercise for the reader:
outer_diameter = 12;
wall_thickness = 1;
barb_size = 0.5;
barb_front_h = 10;
barb_back_h = 1;
nbarb = 3;
// Some derived values
inner_diameter = outer_diameter - wall_thickness;
barb_od = outer_diameter + 2*barb_size;
barb_h = barb_back_h + barb_front_h;
h = barb_h * nbarb;
rotate_extrude() polygon([
for (i=[0:nbarb-1]) let(z = i*barb_h) each [
[ outer_diameter, z ],
[ barb_od, z + barb_back_h ],
],
[ outer_diameter, h ],
[ inner_diameter, h ],
[ inner_diameter, 0 ]
]);
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