From their origins in the American watchmaking industry, collets have been central (no pun intended) to precise metalworking. Yet they are remarkably poorly documented. This is an issue particularly with older machinery, and also with machinery for now less common tasks (for example, the sharpening of cutters by hand in a Gorton 375 cutter grinder, a machine which takes the now rare and rather expensive "4NS" type of collet).
Note: If you're looking for early information on collets, you'll also want to search on these equivalent terms:
Note: A taper which holds by itself is termed "locking," while one which requires either a drawbar to pull it in or a nut to push it in is termed "non-locking."
Gorton Panto-Collet
[NOT DONE; probably a Gorton proprietary collet] This is a style of collet employing a non-locking taper and a nut to retain the collet, as used on Gorton pantograph engravers such as the P1-2 when so equipped. (Gorton also used a different spindle bored with a taper to accept Gorton Taper Shank engraving cutters; see next item).
Gorton Taper Shank Chucks
Gorton's apparently preferred style of spindle for their pantograph engravers employed a locking taper which accepted, directly, Gorton Taper Shank Cutters. (Gorton also used a different spindle with a non-locking taper for Gorton Panto-Collets; see previous item.) To the best of my knowledge Gorton never offered collets to fit this tapered spindle (and I'm not sure that a collet, per se, would be possible - there would be no way to draw it in). However, they did offer various chucks to fit this spindle taper. For these, see the Gorton "accessories" catalogs, such as Form 2720 (links to these are in the Gorton Pantograph Engraving Machines Notebook)
So far as I am aware, no official specification for the taper of this shank is known. It has been measured, however, at 1/2 inch per foot. See: Gorton Pantograph Engraving Machines: Specifications and Reverse Engineering
Gorton Tracer ("Style") Collet
This appears to be a proprietary Gorton collet of unknown official specification.
Rivett New Style Collets
This includes the "4NS" collets used not only on Rivett (and maybe Hjorth?) lathes but also on the Gorton 375 and 265 Cutter Grinders.
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