Posted by Collin Doyle on September 15, 2005 at 01:11:50:
I'm currently making 3 sets of 48 tooth hirth couplings, but I've never made them before and quite frankly, I can't get my head around cutting the pitch diameter of the teeth straight. the crest of the tooth has a 1.814... degree angle sloping inward towards the centre, and the root has the same angle sloping outward towards the OD. I've turned the blank with the crest angle, set up the rotary table on an angle plate to the other angle, but the drawing, and every other drawing I've managed to find online shows the pitch line as being straight. I've cut one set, and although they will work, they aren't correct, as the teeth are only contacting on one point, not across the entire pitch diameter as the should or would with a typical gear. is there a special way to cut these? there's absolutely no mention of it in the bible, machine shop practice books(moltrek, very handy) or any other reference books I can find!
any help would be hot!
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