Hardinge Lathe Designs

I recently got interested in what Franklin Hardinge, a founder of Harding Brothers, the predecessor of the present-day Hardinge Company, had invented. Turns out it's a lot.

  1. US Patent 894,634 "Lathe", to Franklin Hardinge. This is probably his original headstock design. The key is to have thrust bearings (ball bearings) independent of the axial bearings (cast iron sleeves with a precision-ground spindle within). The cast iron sleeves are tapered, and one can adjust the running clearance quite precisely by moving the sleeve, without dange of jamming the spindle.

  1. US Patent 2,419,622, "Lathe Spindle Drive" to Anderson. Anderson realizes that for full accuracy, one must mechanically isolate the lathe spindle from the drive pulley, so the belt doesn't pull the spindle sideways. The solution is to have the pulley running on its own bearings, and drive the spindle through a pin going from pulley to spindle, the pin axis being parallel to the spindle axis.

These two innovations appear on essentially all present-day lathes.

  1. US Patent 4,249,748, "One piece collet and process for making same", to Andrews. US Patent 3,669, 462", "Three and four leaf machine tool collets", to Parsons. Why Hardinge collets are so good.

Joe Gwinn

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Joseph Gwinn
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It's also interesting that the thrust bearings were on the distant end of the headstock, not near the nosepiece. The thrust was first coupled to the pulleys, then through the balls to the cast iron. That has the effect of making any thrust-related deflection happen far from the working end of the spindle.

Reply to
whit3rd

Yes, although I think that that was already well understood.

Yes, but even then there was a significant (to Hardinge anyway) error due to sidepull from the belts. I suppose the remedy of the day was to keep the leather belts loose.

This is what Hardinge Co was remedying in 2,419,622, which was probably prompted by the move to V-belts.

Joe Gwinn

Reply to
Joseph Gwinn

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