Posted by BillS on October 03, 2008 at 20:35:01:
In Reply to: Re: Tangential fly hobbing posted by tom ramsey on October 03, 2008 at 19:50:31:
It seems to me that letting a fly cutter sit at the gear apex would require an involute form cutter, not a rack form cutter.
I agree with Tom - If you assume a single rack form fly cutter, then the tooth profile can only be generated by moving the cutter/arbor tangentially. This would simulate a fixed position hob cutter whose gashes appear to "travel" along a line tangent to the gear.
I think the purpose for tangentially feeding a tapered hob cutter is to gradually take chip loads when throating a w.gear where cutter table is fixed at full depth.
If we wern't talking about a single fly cutter, I suppose that setting cutter at full depth and tangentially feeding is only done where radial in-feed is not acceptable for some reason. It would be great if someone has compared tool life and productivity between infeed and tangential feed when standard hob cutters are involved.
The tapered hob should wind up in the same apex
position with its full depth teeth as an cylindrical in-feed hob so that its multiple gashes can generate the
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