Cut a steal beam

Hi, Im modelling architecture on Blender 2.56a beta. I want to cut a diagonal steal beam with a vertical plane. That should be very easy, but I cant work it out.
First I tried it with a knife tool (k), but I think it isnt implemented in 2.5, because I couldnt find it anywhere. Kkey doesnt work any more. Is that right?
Then I tried it with Ctrl-R, cutting edges, but there is no way to make diagonal cuts on the object. Right?
Then I tried it with boolean modifiers, but when applying them, I get a message that the modifier is disabled. Is there a way to enable it, or is it still erroneous?
Is there another way to get what I want?

Thanks and greetings

with your cylinder layed out horizontally, you can make a loop cut and shear it (space bar, search ‘shear’ or ctrl shift alt S)

but news&discussion is the wrong place to post this - please use the modelling support forum next time

in 2.49 there is a plane knife that you can use to cut any object in 2!

happy 2.5

Thanks for the answers. Next time I will choose the right section, sorry.
Ricky, as I could know the knife works different now. Select face and than hold down Kkey while cutting.
I have to try out shear.

no not knife

it’s a script which use a plane as a cutting tool!
have you seen it ?

happy 2.5

No, I havent seen it. Could you give me a link?

Jeepster, I tried what you proposed. It worked, but the problem is that ‘shear’ also modifies the geometry of the beam, not only the cutting plane. So it doesnt exactly do what I need.

try this one in 2.49

happy 2.5

Ricky, I cant see the link.

Ok, I solved the problem using the boolean modifiers. I think they also work a bit different in 2.5, or I first just did it wrong. Saw this tutorial, which helped me to apply them correctly:

Thanks for your help,

what do you mean you cannot see linK

you click on it and on top left download file


You could also use ctrl-r method and move the verts until the line is diagonal though. It’s a work around and could work but would become more difficult with the complexity of the object.