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Deciphering old drawing for Hardinge 4 degree taper nose


Jul 17, 2016

I've been struggling to make sense of this drawing for a 4 degree taper nose common to Hardinge lathes, in particular the HLV and HLV-H. My research has produced no better drawing, cad model, etc. All of my attempts to model the geometry have failed, almost certainly due to my misinterpretations of the drawing below. My questions are embedded in the drawing, along with superimposed lead lines to illustrate the geometry. I have also attached two copies of the original print, note that the PDF is "slightly" higher quality. Any guidance is appreciated...



  • Hardinge No. 5 taper nose dwg..jpg
    Hardinge No. 5 taper nose dwg..jpg
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  • Taper Nose 5C.pdf
    74.6 KB · Views: 6
A1. Yes.
A2. It doesn't much matter. Your three red circles are practically stacked on top of one another in the plan projection, and you have 0.005" of tolerance which is more than enough to cover any discrepancy. Notice that the grooves have 4 degrees per-side of draft, and that the bottom of the axial groove is tilted the other way the same 4 degrees. So all three red circles should be precisely aligned in the plan projection.
A3. No reason to assume the lead is one anything per revolution. It needs to be Goldilocks in-between too large a helix angle to jam and self-lock the index pin inside the chuck internal taper and too small a helix angle to require too large a rotation for the index pin to jam or too tight a tolerance to produce efficiently. Presumably Hardinge's engineers looked at a handbook for self-locking angles of steel on steel and picked something reasonable in that range.
Or, if you prefer, the angle is the functionally interesting value. They are giving it in the plan projection, so any compound angle nonsense was sorted out in the drafting room. The lead can be thought of as a REF value for the shop.
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