Standard Tapers - Continued

as end mills and reamers, the taper being approximately 1/2 inch per foot

for all sizes except for taper No. 10, where the taper is 0.5161 inch per

foot.

3 The American Standard Machine tapers are composed of a self-

holding series and a steep taper series.

The self-holding taper series

consists of 22 sizes.

The name "self-holding" has been applied where the

angle of the taper is only 2 or 3 and the shank of the tool is so firmly

seated in its socket that there is considerable frictional resistance to any

force tending to turn or rotate the tool in the holder. The self-holding

tapers are composed of the selected tapers from the Morse, the Brown and

Sharpe, and the 3/4 inch per foot Machine taper series. The smaller sizes

of the self-holding tapered shanks are provided with a tang to drive the

cutting tool. Larger sizes employ a tang drive with the shank held with a

draw bolt. The steep machine tapers consist of a preferred series and an

intermediate series. A steep taper is defined as a taper having an angle

sufficiently large to insure the easy or self-releasing feature.

Steep

tapers have a 3 1/2 inch taper per foot and are used mainly for aligning the

milling machine arbors and spindles, and on some lathe spindles and their

accessories.

4 The Jarno taper was originally proposed by Oscar J. Beale of the

Brown and Sharpe Mfg. Co. This taper is based on such simple formulas that

practically no calculations are required when the number of taper is known.

The taper per foot for all Jarno tapers is 0.600 inch per foot.

The

diameter at the large end is as many eighths, the diameter at the small end

is as many tenths, and the length as many half-inches as indicated by the

number of the taper.

For example: A No. 7 Jarno taper is 7/8 inch in

diameter at the large end; 7/10

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