Bulletin 100-B of Rivett Lathe and Grinder Inc., Draw-In Collets and Chucks, contains much useful information. This link to it at: http://www.neme-s.org/Shaper%20Books/Rivett_Lathes/Section_4/Rivett%20Disk%204/Rivett%20Collets%20B100-B%20%5BPDF%5D/4_Rivett_Collets_B100-B.pdf might work. If it doesn't, see ../ General References Concerning Collets -> Rivett Bulletin 100-B for information on how to find it online.
Bulletin 100-B clearly identifies the meaning of "NS" as "New Style" and the origin of the collet with Rivett. Thus a Rivett collet marked "5 N.S. RIVETT" is identified as "Rivett No. 5 New Style". ("OS" is pretty clearly then "Old Style," though I suspect that OS collets were not so identified before the introduction of NS collets.)
Bulletin 100-B gives dimensions for Rivett Nos. 3, 4, 5, and 6 NS collets (but not the taper angle). Tom Hammond, in a posting to the "Rivett-608" Yahoo! newsgroup on 2011-06-30, additionally gives the taper angle for NS collets and the data on the 2NS / "Ideal" collet. Many thanks to him for this information, especially the angle information (which was impossible to find otherwise).
|Style of Collet||A||B||C||D||Half-Angle||Max. round||Max. square||Max. hex|
|Rivett No. 2 N.S. / "Ideal"||0.325||0.322||40||1 17/32||15||1/4||?||?|
|Rivett No. 3 N.S.||0.6875||0.650||20||2 7/8||15||1/2||11/32||7/16|
|Rivett No. 4 N.S.||0.826||0.812||20||3 1/2||15||5/8||7/16||17/32|
|Rivett No. 5 N.S.||1.062||1.050||20||4 7/32||15||7/8||5/8||3/4|
|Rivett No. 6 N.S.||1.3125||1.250||14||4 7/32||15||1||23/32||7/8|
These sources do not give the length of the threaded portion, the dimensions of the keyway, the length of the slits, or the amount of doming at the working end of the collet. These are, of course, less critical dimensions. [TO DO: measure some]
Note that some sources online claim that the Rivett New Style collets are the same size as equivalently numbered Rivett Old Style collets except for the thread diameter. An examination of the table in Bulletin 100-B shows this to be untrue. The diameter A of the Rivett No. 4 N.S. collet, for example, is 0.826 while the diameter A of the Rivett No. 4 O.S. collet is 0.750.
A modern Hardinge brochure, Spindle Tooling for Manual and CNC Lathes , generally agrees with the data in Bulletin 100-B for 4NS collets (Hardinge part number 1625), but gives a slightly different value for "B", the diameter of the threads: 0.800. Presumably Hardinge has relaxed the thread fit slightly.
This table in Bulletin 100-B also gives sizes for several other collet ranges, including Hendy, Cataract, LeBlond, Seneca, South Bend, and Becker. Note that the Cataract No. 5 is the now ubiquitous "5C" collet. Its dimensions are given here as:
|Style of Collet||A||B||C||D||H||Max. round||Max. square||Max. hex|
|Cataract No. 5||1.250||1.245||20||3 9/32||3 11/32||1||23/32||7/8|
Spindle Tooling for Manual and CNC Lathes. http://www.hardingeus.com/usr/pdf/collet/2348E.pdf, p. 43.
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