Posted by Dimebag on December 12, 2015 at 03:58:03:
In Reply to: Re: Fly Hobbing - Substitute Hob Shift for Tangential Feed? posted by gearhead1 on December 10, 2015 at 15:14:50:
Won't work. Will cut in the center, +1 Axial Pitch and -1 Axial Pitch might cut a little, +2 AP and -2 AP might not cut at all- you can only feed in or plunge to the same radial position as in the center, or you will damage the teeth. The teeth profile will have edges, since there would be only a few cutting positions. For a medium size worm gear, typically you need at least 8 cutting positions per Axial Pitch of the worm which can make approx. 30 cutting positions overall. If you shift 1/8 of AP, you need to superimpose it on the rotary position of the pitch diameter of your worm gear. That's what tangential feed does. I can imagine you could calculate how much shift results from rotating of a suitable change gear with its shaft by a defined number of its teeth and shift the cutter that amount each time. First set the cutter in the center, scratch the blank, shif to the side, approach to the depth, shift to scratch, and that would be your starting position. Then back out, rotate and shift, feed in to the starting point radial position, repeat many times until you get to the other side of the worm gear. But you would need a lot of patience and time.
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