How to cut a circular opening on a tube

[detbear]

Hey Everyone....

 

I was hoping to avoid a boolean here.

 

 

Is there a way to cut a circular opening in the side of a tube in A:M without using a boolean operation?

 

Thanks so much for any suggestions.

[Gerry]

Seems like Robert or someone did a series of tests for something like this, but I don't think it was cutting a circle in a curved surface. You might want to make the big cylinder with more splines. My short answer would be "yes" but offhand I'm not sure how. Off to the lab!

[zandoriastudios]

Why don't you want to use a boolean cutter?

[Gerry]

Well, here's my entry. It's not perfect but I do recall *someone* doing some very elegant tests on a problem like this not long ago. However the model I'm posting has a very strange anomaly, two five-point patches that will not render no matter what I try. So, hope this helps, but I'm sure there's a better solution.

cylinderWithHole.mdl

[robcat2075]

You will need the cylinder to be splined so that point where you want to punch a hole presents 2x2 arrangement of fairly squarish patches. Then you can splice in a four-point loop around the center point, break the splines in the middle of the new circle, adjust the biases so it's appropriately round and extrude it through to the inide where you have done the same thing on that surface.

 

A boolean is easier.

[robcat2075]

Basically what Gerry did!

 

The 5-pointers are not closing because the center spline at the top has two CPs in the same location. Select it, press teh detach button and you will be able to drag it away and delete it.

[detbear]

Thanks everyone....

 

Thanks Robert......Guess that's the way.

 

Gerry.......Looks good to me...I've had issues like that with 5-pointers myself.

 

William S. .......I'm trying to avoid any rendering heavy weights. And the model needs to

have some other visible elements on the inside and where the boolean would be.

That said....The boolean may not be a problem, but I don't use booleans enough to know

the in's and outs of how they effect renders that way.

[itsjustme]

Here's my attempt (not perfect, but passable)...maybe a little late.

tube_test.mdl

[Rodney]

the model needs to have some other visible elements on the inside and where the boolean would be.

 

Just for the record here... I know you are trying to avoid booleans.

 

If you assign part of an object to one bone and the boolean cutter to another the cutting will only effect that part of the object that the boolean cutter is a child of. In this way you can have objects inside the space created by the boolean cutter.

[John Bigboote]

I decided to take a quick swing at this... NICE EXCERCISE! I went for a bigger hole, but I too, am running into 2 kitty-corner 5-pointers that will not close. Rob, can you take a look at this one too?

tubewithhole.mdl

[Rodney]

There are a couple issues going on with your model Matt.

 

(I think) normals facing the wrong way were an issue. (I tried to repair them in the attached)

 

The real issue however (and not necessarily related to why the 5 pointers would not close) is that due to the thickness of the tube you were in the process of creating internal patches. The way I got around this was to create a mid point spline circle inside the hole. I'm not entirely convinced but it's possible that these internal patches were related to why A:M did not want to create the 5 point patches.

 

To fix the 5 pointers I just went back in and detached reattached so I'm not sure what the issue there was...

 

Note: I didn't take the time to go back in and adjust spline biases so the tube is a bit deformed.

tubewithhole_somewhatrepaired.mdl

[Kamikaze]

I love seeing these things worked out..I remember having all sorts of problems with this on my C-130 aircraft port holes .... I'm sure someone on the forum help me out all I remember is a lot of spline handle adj. not a fan of booleans for this purpose.....and thanks all for the mdl files...

[largento]

I thought Eric Camden had done a tutorial on this very thing, but couldn't find it. I wonder whatever happened to Eric. His profile says he hasn't visited the forums in over a year. He was doing a lot of really cool stuff while he was here.

[Rodney]

Okay... I couldn't resist.

Here is a tube moving through a tube that has three different colored beveled holes cut out of it.

 

The project file should have everything necessary in it.

Keep in mind that you have to render to see the cutaway from the tube (that's the downside of booleans).

I added a negative light just to add a little contrast to the scene.

 

A few tech notes:

The inner tube doesn't get cut by the boolean shapes because it is assigned to a bone that is a child of the bone that is set to be a boolean cutter. If it were higher in the hierarchy with the bone set as a boolean cutter as a child of it, it would cut through both tubes.

 

The red, yellow and green colors on the beveled holes are driven by the surface color of those objects. If you applied a material to those groups it would display that material. All three cutting shapes are assigned to the same bone although they could be assigned to different bones that each had the Boolean Cutter set to On.

 

Apologies for posting what you don't want here but it's one way to get at cutting holes in tubes.

It might work on a different project some other day.

booleanbeveledtube.mov

BooleanBeveledTube.prj

[Rodney]

Depending on your goals there is another way to approach this...

 

You could fake it!

 

Here's a an example where I have just placed three objects together to make it look like there is a hole in the tube.

 

What is there is actually two tubes and a 5 point circle (there is an ancient chinese recipe for that).

Fakeit.mov

[detbear]

Rodney,

 

Nice looking test. Thanks for posting.

 

After experimenting with trying to create the hole by adding splines with

the four 5-point patches, I found that the 5-pointers have a terrible "concave"

trough that I couldn't get rid of. The bias handles being moved to help this

makes the circle an oval. I'm sure that somehow that can be fixed, but so far

my splinemanship isn't getting it done

 

Maybe the boolean approach may be a better option after all. At least at this point.

[Rodney]

I'm pretty partial to the Boolean approach but the fakin' it approach can work pretty good as well.

 

Just placing your shapes together and using a texture/material to blend them into one shape might work in some instances.

 

Attached: Not the best example but an example of just placing shapes together.

[robcat2075]

I'll note that you may have more success with modeled holes if the 5-pointers are from fairly squarish patches and if they come up to a ring around the hole rather than try to be the edge of the hole itself.

[Gerry]

Basically what Gerry did!

 

The 5-pointers are not closing because the center spline at the top has two CPs in the same location. Select it, press teh detach button and you will be able to drag it away and delete it.

Y'know I knew it was an extra cp or two somewhere, but I looked and looked and couldn't find it. But man, I step away for a day or two and look at all the investigation going on! Great work everyone.