Machining Bevels.

[Nate]

Hi:

  Bevels will be dealt with in a waterline engraving module, but probably not till next fall.
...

Naively, it seems like the easiest way to cut bevel gears on a 3-axis CNC machine would be to generate a gear profile numerically, and then profile cut with a ball nose end mill, but I haven't seen any discussion of that in the thread.  Is there some compelling reason not to take that approach?

[ArtF]

Nate:

Thats the plan. Its not easy to cut bevels, but for beverls less than 45 degrees, the workbench shoudl be
able to profile them, for more than 45 degrees, he 4th axis shoudl eb able to profile them..

Art

[Nate]

That's the plan. Its not easy to cut bevels, but for bevels less than 45 degrees, the workbench should be
able to profile them, for more than 45 degrees, he 4th axis should be able to profile them..

A bevel gear with lots of helicity, a small pressure angle, and large teeth can have both radial and axial overhangs.  (That is to say, require a 'tilt' or 5th axis set up.)  I'm not sure whether gears like that have any practical application.

This is a section of a decorative bevel gear I  modeled.  If the pitch cone angle were larger, you can see that there would be a 'double undercut'.

[ArtF]

Nate:

Couldnt agree more. Fact is, bevels are hard, Ill try to make it so some work, some dont, basically we'll just have ot
live with whatever we ifnd the limitations are...unless we all want to buy 5th axis machines.. :)

Art

[Nate]

Couldn't agree more. Fact is, bevels are hard, I'll try to make it so some work, some don't, basically we'll just have to
live with whatever we find the limitations are...unless we all want to buy 5th axis machines.. :)

On second thought, it may be possible on that 4th axis after all, but it will require the cutting tool and the gear axis to be skew to each other.  (I'm not sure what the right term for that is.)

Just for fun, a 45 degree chevron bevel gear section - these really want to be 3-D printed, if anything.

[ArtF]

I must admit, bevels is one reason I like 3d printers.. :)

Art