Posted by Bill Simpson on November 27, 1999 at 22:14:31:
In Reply to: 45 helix angle posted by Robert Vatieri on November 27, 1999 at 08:15:43:
Could you describe what's breaking? Is a G&W a hobbing machine? Is the gear LH or RH?
If you are hobbing, cutting high helix angles can cause climb cutting action to occur for one hand of gear. When the cutter rotation and workpiece rotation oppose each other, the machine should be "happy" to cut that hand of gear. However when the cutter is trying to "help" the workpiece rotate (climb cutting), then any backlash in the workpiece spindle is bad.
Even worse is the possibility that the workpiece might be rotated on the arbor by cutter impact forces.
At 45 degrees, rotational and axial cutting forces are equal.
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