Posted by BillS on February 27, 2014 at 18:30:29:
In Reply to: hobbing quadruple acme thread posted by Jim Pollock on February 26, 2014 at 21:36:40:
If you did it on a differential hobber, using a single point "fly" cutter, it would require index gears in a 4:1 ratio (so that each rev of the cutter would sync up with the next thread). The differential would have to be set to advance (or retard) the workpiece with the required helix angle, which would be 90 - lead angle.
I think that would work with a small table feed. Not sure if the tool would hold up well, but if the table is swung to the helix angle, grinding tool relief should minimized.
I'm trying to visualize axial versus normal circular pitch; not sure which would be resulting angle - anyone?
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