[HaroldSAJS]

Hi,

I am new to CNCZone forums. I want to post a question and I am not certain where to post my question. The subject matter is 'conical boring', as in boring a cone into a solid block of aluminium that starts at 6.968" diameter, and ends at .250" diameter, over a 7.776" length. Can anyone tell me where I should post this question?

[keebler303]

I assume this is on a lathe?

Drill a hole in the middle just shy of your finished size, then use progressively bigger drill bits or a boring bar to step in the cone, each pass will be slightly less depth to form the rough shape of the cone. If this is on a CNC machine, the finish pass is trivial. On a manual machine, you probably don't have enough compound slide travel so you will have to do it in sections and try to blend them together as best you can. Your boring bar should be fat to stay rigid and then should have a fairly small tip so you can get down to the 1/4" finished size.

Matt

[HaroldSAJS]

Thanks for the advice! Do you know of a manufacturer which makes a boring bar that can do what you are suggesting? Where the boring bar shank is larger than the head!

Again, thanks for the advice! Any additional help you can give, is much appreciated.

[keebler303]

I have a whole box full of them in the basement. Any old boring bar will get you down close to 1" diameter. For the last part, I'd use a big bar that has a set screw bore in it, like an extension basically. Put a normal little brazed carbide boring bar in there and go to town. You could easily make what I am describing if you don't have something like that laying around.

Matt