Cutting holes in a cylinder

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  05 May 2007
Cutting holes in a cylinder

Need a hand cutting holes in something cylindrical. Am modelling a Browning M2 .50 cal heavy machinegun for a showreel piece.

I need to cut holes in the heatsink around the barrel, and I need it to be high detail and smooth. I've tried using a low poly cylinder, cutting holes in it, welding excess vertices, cutting a grid into the mesh to give it a better topology and then applying NURMS. The result i get is this...

http://i2.photobucket.com/albums/y3...rior/m2wip3.jpg

clear bevelled edges where the smoothing has affected the edges.

Now i've tried re-modelling it with a much higher poly cylinder to start with, but whenever I try to use Boolean it cuts a hole in the top surface but not the inner surface. ProBoolean crashes Max every.single.time I use it for this operation. Both meshes are closed.

http://i2.photobucket.com/albums/y3...rior/m2WIP4.jpg

That's what it looks like right now, before the boolean operation has completed.

Anyone have any suggestions?
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  05 May 2007
Never use boolean if you can avoid it (and in almost all cases, you can avoid it, with a little extra work).

One of reasons you are getting those weird creases is because you don't seem to have enough geometry in that area to support those kind of cut outs. I would suggest getting a cylinder with a lot of sides, do some cutting, and extrude the holes out (even using a 4 sided cut out will be enough). Then run mesh smooth with 2 iterations (to make the square holes become round). Of course you'll have to set this up properly (making sure the edges are sharp where needed, and round where needed), but keep it quad, and you should be good to go.
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  05 May 2007
hey cap-

i think nurbs may be a better choice here... i think the nature of the shape would make it easier in nurbs. im not sure about the entire max toolset, but is that something you would be willing to explore?
 
  06 June 2007
I made this exact same model and had this problem as well. The secret is to start out with a plane, not a cylinder. you cut in your holes and edit your geo however you want. you then use a bend deformer to wrap the plane into the cylinder shape you're after.
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  07 July 2007
Originally Posted by itsallgoode9: I made this exact same model and had this problem as well. The secret is to start out with a plane, not a cylinder. you cut in your holes and edit your geo however you want. you then use a bend deformer to wrap the plane into the cylinder shape you're after.


Ooo very good idea.
 
  11 November 2007
^I second that!

but it usually works just to make the big cylinder with a massive number of sides (60 to 120 maybe) and maybe ad some edgeloops intersecting the centers of the holes for good measure.
 
  11 November 2007
You don't need a lot of geometry to do this, you just need to know how to set up the topology. Here is some stuff I have learned over the years. If you need a max file let me know and i'll make one for you.

Last edited by Ashford_Butler : 11 November 2007 at 12:44 AM.
 
  03 March 2008
How about making the cylinder long enough for just one set of holes, then duplicate, put on, and weld as you require for length ?
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  03 March 2008
A Good Technique for doing this is to cut the holes into a flat plane and use a bend deformer to turn the plane into a cylinder. You can start low poly then apply mesh smoothing either before or after the bend deformer.
 
  03 March 2008
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