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Old 3rd March 2011, 06:16 PM   #11
AllenAnway
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Smile Re: Make a hole in a surface

It worked successfully just like you said. I was missing the <shift><select> step to select the second smaller piece after first selecting the larger piece. Thanks for all your work to help me. This allows me to continue with my project.
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Old 2nd May 2012, 12:35 PM   #12
jleslie
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Default Re: Make a hole in a surface

ok, I tried to apply this procedure to my app but I made a mess. I hope someone can point me in the right direction.

here is my model so far with the mistake:

the parts with the red X are the mistakes. what I was trying to do was cut a
tube out of the center of the 11 conic sections of the teardrop stack of cones, the idea is that the long thin cylinder down the center (a copy of it is wire framed) I wanted to cut out of the 8 cones that make up the other shape that I red x'ed. what happened when I did the cut and such was a duplicate structure of which I was able to take out the center cylinder. I realize now all I did was a cut and paste of the original, but I'm sitll not getting how this knife thing is supposed to cut through the 9 of the 11 conic sections of the main body.

TIA,
Jleslie
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Old 2nd May 2012, 01:57 PM   #13
jleslie
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Default Re: Make a hole in a surface

ok bringing it down to just one conic section, and the cylinder.

1) I select the conic section as an object, the cylinder is not turned green.
2) I hold the shift key, right click down and hold on the mouse, box the cylinder, let go of the mouse, and now both shapes are turned green.
3) I click on Object-->Boolean-->Knife and Cut Away I get the error message:

"Knife: 2nd object has open edges..."

see attached.
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Old 3rd May 2012, 11:46 AM   #14
Terry Capps
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Question Re: Make a hole in a surface

When you made the Cylinder, did you "cap the Ends" ?
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Old 3rd May 2012, 01:34 PM   #15
jleslie
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Default Re: Make a hole in a surface

Quote:
Originally Posted by Terry Capps View Post
When you made the Cylinder, did you "cap the Ends" ?

I've tried it both ways. I was able to get it to work, but it was not obvious and very time consuming. what i did was:
0) set object mode
1) define the cylinder to be the knife.
2) made the conic section to be cut the hi-lighted object
3) used the tools-->knife-->slice surfaces. this told me in bottom status area that a bunch of the lines got cut.
4) pulled the conic section to the side, and I could see the new vertex's on the conic section. I can now see a bunch of vertex's unconnected on the surface in the shape of the circle of the cylinder at the point that the cylinder contacted the surface of the conic section.
5) switched to vertex mode.
6) grouped pairwise vertex's and made them hi-lighted, and then used vertex-->slice surface (<cntrl><shift>L). this made the little line between the the vertexs. sometimes I could grab more than 2 vertexes at a time, sometimes I couldn't.
7) repeated that for all the new vertexs of he circle of vertexes that the knife left behind.
8) switched to surface mode.
9) grabbed the surfaces inside the circle and started to delete them. sometimes I had to delete them twice before it "took". also the renderer got very confused, and when I hi-lighted the inner surface it also hi-lighted the outportion. It took a while for me to realize the the renderer was messed up and not the delete function.

10 I then carefully placed the conic section back on the stack where I wanted it.


I had to repeat this for 9 of the conic sections. this was very time consuming and I assume there must be a faster way of doing it.


this appears to work on the end of the conic section because of the even-ness of the spokes of lines of the circle endcap of the conic section. I made up a solid polygon flat surface and for the life of me I couldn't get the the knife function to leave the new vertex's down on the surface of the polygon.
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Old 3rd May 2012, 06:42 PM   #16
Stiglr
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Default Re: Make a hole in a surface

When forced to create an aperture in a polygon manually (and it's often well worth it, because Booleans usually create a horrible mess!), I often use this tactic:

1) Reduce/simplify the polygon to a single surface.
2) Select the surface in Surface Selection Mode.
3) Surface > Make Hole. Insert or delete vertices among the hole vertices such that the hole has the same number of vertices as you want the hole "cylinder" to have.
4) Create a disk object, with the same number of segments that you want your hole to have. Size/scale the disc to the size of the hole.
5) Drag the disk over the polygon, position and then "Lock:" it so it is visible but non-selectable.
7) In Vertice Select Mode, select the vertices that comprise the inside of the hole you created in the polygon. Drag these directly over the vertice points of your hole polygon.

Basically, you're "tracing" the hole, using the disk object as a positioning guide.
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Old 3rd May 2012, 07:17 PM   #17
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Default Re: Make a hole in a surface

Quote:
Originally Posted by Stiglr View Post
When forced to create an aperture in a polygon manually (and it's often well worth it, because Booleans usually create a horrible mess!), I often use this tactic:

1) Reduce/simplify the polygon to a single surface.
2) Select the surface in Surface Selection Mode.
3) Surface > Make Hole. Insert or delete vertices among the hole vertices such that the hole has the same number of vertices as you want the hole "cylinder" to have.
4) Create a disk object, with the same number of segments that you want your hole to have. Size/scale the disc to the size of the hole.
5) Drag the disk over the polygon, position and then "Lock:" it so it is visible but non-selectable.
7) In Vertice Select Mode, select the vertices that comprise the inside of the hole you created in the polygon. Drag these directly over the vertice points of your hole polygon.

Basically, you're "tracing" the hole, using the disk object as a positioning guide.

LOL!!! I sorta did that backwards. I tried that with my odd-shape polygon, but the vertex's kept overlapping and being hidden (I'd see a black surface instead of a white one.) So I did it a way I wouldn't have overlapping lines and odd shapes.

1) start with a disk with 32 sides.
2) using the knife with a cylinder of 32 points, cut out the center of the disk making a donut.
3) place the donut so the donut hole is over your polygon where you want the hole.
4) change to vertex mode
5) start dragging the vertex's of the outside of the donut to points on the outside edge of your polygon. when you finish with all 32 you have your original polygon with a hole in it.

you can see that in the far polygon (polygon B) of the last picture I took. That's how I did it.

I was hoping for something less verbose.

Last edited by jleslie; 3rd May 2012 at 07:36 PM.
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Old 3rd May 2012, 07:32 PM   #18
jleslie
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Default Re: Make a hole in a surface

I just don't understand why this is so obtuse and difficult (for all 3d software not just ac3d)

I mean ac3d is like 80% there, I can make a specialized "knife" but adding the vertex's to a surface and then making polygons from vertex to vertex is very hard.

That <ctrl> <shift> L works "some" of the time but I can't figure out its reasoning. the error message is ridiculous.

AC3D has one of the best viewers and fly-overs there is, I can see the points of intersection of the knife and the surface. All it needs is for me to be able to "box" an area that frames a point of intersection, let it then add a vertex on the surface in that box, and then I should be able to grab 3 or more vertexes and make a polygon.

If I could just delete or add those polygon lines on a surface and have the ability to add a vertex in an object on the surface, I'd be all set.

For example, in polygon A, above, its some 30 or 40 vertex's that I made into the shape. as a result, is odd shaped, but it has 1 surface. I should be able to grab any two (non adjoining) vertex's and cut the polygon into 2 surfaces by having that "cut line" drawn between the two.

I don't know if I'm explaining that right.

Maybe my problem is the "make a hole is way to complicated, it makes a mess out of my shape. I would be great if "make a hole" worked like the polygon draw button. It shouldn't remake its best guess at what kind of hole I want, but rather just allow me to click on points on the shape and draw a polygon onto the existing shape and when I close the polygon by hitting the escape button, instead of drawing a polygon it removes that portion of the surface for the points on underlying polygon.
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Old 4th May 2012, 12:23 PM   #19
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Default Re: Make a hole in a surface

jleslie wrote:
Quote:
I tried that (Make Hole) with my odd-shape polygon, but the vertex's kept overlapping and being hidden...
That's due to the odd shape of the polygon, and the desire to end up with a round "hole". I imagine you'd need to either set the Make Hole % low, so that the vertices are created and grouped closer to the center of the object, and/or remove (or Snap/Weld!) some of the vertices to get a smaller number of vertices remaining on the interior hole.

I hear (and commiserate with) your frustration at the need to sometimes draw surfaces "by hand" (e.g., select three or four vertices counterclockwise, and Ctrl+Shift+S) but sometimes that's the best and cleanest way to get what you want. Booleans just won't do it properly, and you'll spend more time cleaning up Boolean mess than you will with other methods.
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