The angle needs to be just slightly less than 90 degrees/ an acute angle.
It all depends on obstructions/ getting the tool in where you want to make a cut.
Many times a tool has to be custom ground for a particular application.
The acute angle can be anywhere from 89 degrees to 10 degrees.
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Edit, checked back 12 hours later.
6-17-2010 @ 6:00 PM
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