3d shape slicing problem

I am attempting to teach myself how to drive autocad as my colleagues use it all the time.

In order to learn I am drawing bits I use at work. One is a component which is basically a cylinder with flattened sides and a curved top.

So

I made a cylinder and then sliced out the sides to make it have the flattened sides. Brilliant!

I am however having a problem getting the top curve.

My thinking goes to make an intersecting cylinder at 90degrees then use this as a cutting edge to slice off the bits of my flattened cylinder that stick out. Then delete this intersecting cylinder leaving my flattened side curved top component. However this process stops working when I try to select my cylinder as a cutting edge as my version of cad seems to be looking for a 2d surface or object to use as the cutting edge..

One of my colleagues said I should draw an arc to make my curved top and then punch it through the flattened cylinder and it will work. Unfortunately he said this to me in the pub last night and we did not have a computer with me so I don't quite remember what he said.

If someone can offer any help I would be very grateful.

I'm using autocad 2007 on my mac running it through Parallels in a vista virtual machine.

Something like this?

Yes indeed but the top isn't a full hemisphere just a part of a curve which is why i did the intersecting cylinder

Good guess I my part then.

I combined a cylinder with a sphere and then sliced off two of the sides. Pretty straightforward. Now go forth and recreate (your sliced curved-top cylinder that is).

Finally sussed it.

The cylinder and then slice option wouldn’t work so had to do an arc, then extrude it and then turn it into a surface. Then use that as a slice surface.

Am I chuffed of what?

http://www.flickr.com/photos/brixtonbanner/

I would draw a 1/4 section of that part and use the revolve command, then slide or even subtract. Revolve would unfortunately not work for the non hemisphere top portion though at that would be another operation.

If you extrude a line or use sweep(line and path) you can create a surface for the top to use for slicing.

one thing you will find is there are many many ways to achieve the same thing. It will be up to you which one will be best/most efficient. Any time you can simplify things by taking care of many aspects at once you will be helping yourself out.