If we have to do it on this end it is really expensive as it must

be done on an NC mill or on a rotary table and an ordinary
mill. No other practical way of doing it.

How about a hole saw?

Brian Trubee

Due to the pie shape of the ribs you will hardly get enough useless 
material out of there to make it worth while. Think of a cast
aluminum spoked wheel. It is easy to figure out the weight
savings. Multiply the volume in cubic inches of material removed
by .1 which is the density of aluminum in pounds per cubic inch. 

Paul Lamar
 
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