Need to punch a hole into a tube


I am very new to blender, I’ve been following the tutorials but I’ve not been able to punch a circular hole into the side of a tube (I’m modelling a hydro electric generator), I’ve tried to use the boolean operator “difference”, but it does not result in a clean hole, it warps the surface of the tube…any ideas?

Many thanks…


try using the knife tool…k i think

If the tube has a decent number of sides you can do it like this.

1). Make 2 loop cuts in the tube
2). Remove some faces, this will make a square hole
3). Move the verticies on the edges along the length of the tube until you get the hole into a round shape.

Thank you for the very quick reply,

I did try that very technique, but it seems to warp surrounding surfaces…

Here is a picture of what I’m trying to model, as you can see there are lots of holes…

as you can see, I’m just asking for trouble…

I wouldn’t try to model all those holes if I were you . It would be better to normal or bump map them or even just UV unwrap and paint the holes in .
If you are mesh modeling them you will find it is almost impossable to do a proper circle winout a ton of vertices . If you are going to create the complete scene like the picture and you model in every hole you will be waiting a loooong time to render .
Unless you have an idea for some small creature to pop in and out of the holes - I’d just fake it with a bump/normal map or just paint the holes in .

This is easy enough process so I’ll walk you through it…even with pictures :slight_smile:

1.) Add a cylinder primitive on the screen
2.) Use loop cuts (K) to mark out where you want the hole to be.
3.) Delete the middle vertice
4.) Select the vertices around the sqaure whole using Alt+RMB (right mouse button) then Shift+S->Cursor to selection. Then hit the To sphere button (using 100) and you should be set.

Vertex Pusher is right, this will leave you with a lot of vertices so I would go with bumpmapping, if you don’t know how to do this you can go watch this video that explains it pretty well


Here’s what I would do for something with that many holes.

I’d make a section with the holes modeled into it.
Then I’d duplicate that and position it until you have a long line of sections with holes.
Then I’d use the warp tool to warp it into a circlular shape.

The warp tool is very handy for circular objects that require a lot of repetition or detail.

My sincere thanks to all of you for your advice. I thought about creating a single section as it’s all just a repetition of the same thing over and over.

I can see your point about just painting in the pattern, I really don’t need them to be true holes but I got very stubborn and just wanted to know how the heck to get it to work. I’m going to try all your suggestions just as a learning exercise and see which one works the best.

Thank you all for your help…great participation on this forum!


I created a texture based on a close up photo of the vents, applied the texture and multiplied it 32 times along the x-axis…

Looks pretty good!

Thank you for all your help…

yea that looks good, now what you can do is crop out all that light blue, leaviing just the black holes, and do some bumpmaping…this will give the holes the appearance of having some depth to them.

You could try to alpha map those holes, you know- it will create a more realistic result than just painted black spots. What I mean by alpha mapping is creating a texture that has some transparency in it (the transparency could create the holes you are looking for)