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Diametral Knurling Information

Standard Diametral Pitches

For Example:

Increasing the angle between the knurl axis to approximately30 1/4° would provide good tracking of the knurl and make itpossible to obtain an even 83 teeth instead of 83.14.

By reducing the diameter of the work blank to a decimal size,good tracking of the knurl can be obtained for 30° diagonal knurlingaccording to the following formula:

The number of teeth produced on the work blank is measuredin the transverse plane and may be determined with the followingformula for diagonal knurling.

Nw = Dw x P x cos ¥

Dw

NwP=

Equivalent Normal TPI of Dimetral Pitch KnurlsAll Diametral Pitch Knurls made to American Standards (ASA B5.30 1958). DiametralPitch Knurls produce the D.P. number of teeth per inch of diameter. Rolled CircularPitch Knurls, produce the TPI number of teeth per inch of circumference measurednormal to the teeth.

Work Blank Diameters

P=Diametral PitchWhere:

Nw=Number of teeth on work, or P x D

w

Nw

Dw=Theoretical work blank diameter or

P¥=Angle between knurl axis andwork axis. (cos 30°=.86603)

8396 x .86603

Nw

P x cos ¥Dw= .998 inch= =

The tolerance for work blank diameters vary with the knurlingrequirements. For general purpose knurling the tolerancesgenerally range between 5 to 8% of the circular pitch and forprecise knurling, approximately 2 to 4% of the circular pitch.

Request for Diametral Blank Diameters

The four standard diametral pitches available are 64, 96,128, and 160. The 96 and 160 diametral pitches are for blankdiameters having fractional increments of 1/32" and the 64 and128 diametral pitches are for blank diameters having fractionaldiameters of 1/64". The American Standard recommends thatthe use of the 64 diametral pitch should be avoided as much aspossible, and for simplification of tools, preference be given tothe use of 96 diametral pitch.

The term diametral pitch applies to the quotient of the totalnumber of teeth in the circumference of the work divided by thebasic diameter of the work blank. The diametral pitch is the ratioof the number of teeth on the work to the number of inches ofbasic work blank diameter and equals the number of teeth toeach inch of basic blank diameter.

Approximate Increase of Blank DiameterStraight and Diagonal American Standard

** Refers to transverse TPI and transverse circular pitch on diagonal knurling.

The diametral pitch and the number of teeth are alwaysmeasured in a transverse plane which is perpendicular to the axisof rotation for diagonal as well as straight knurling.

A comparison of diametral pitches, TPI, and circular pitches isshown below.

Diagonal and diamond knurling on work blank may beaccomplished by setting the axis of straight knurls at an angle tothe work axis.

When using straight knurls to produce diagonal and diamondknurling by end-feeding, the transverse diametral pitch that isproduced on the work will not be the same as that of the knurl. Thediametral pitch in such instances refers to the diametral pitch onthe knurl rather than the knurling produced on the work.

Where:P=Diametral Pitch

Dw=Theoretical work blank diameter or

Nw=Number of teeth on work, or P x Dw

Nw

P x cos ¥

P

Nw

For end-feed knurling with straight tooth knurls:

Dw=

Dw=

Where:P=Diametral PitchN

w=Number of teeth on work, or P x D

w

Nw

Dw=Theoretical work blank diameter or

P

P=Diametral PitchWhere:

Nw=Number of teeth on work, or P x Dw

Nw

Dw=Theoretical work blank diameteror P¥=Angle between knurl axis andwork axis. (cos 30°=.86603)

The formula for theoretical work blank diameters are as follows:

If 30° diagonal knurling were to be produced on 1" stock witha 96 diametral pitch straight knurl.

Nw

= 1.000 x 96 x .86603 = 83.14 teeth

Note: .86603 equals cosine of 30°

Nw

P

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46 4.02 1940. 420. 120. 42 1-8/3 46/1

69 6.03 7230. 610. 410. 42 1-4/1 23/1

821 7.04 5420. 210. 010. 81 1-46/9 46/1

061 9.05 6910. 900. 800. 51 1-23/3 23/1

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69 7230. 6.03 3.53

821 5420. 7.04 0.74

061 6910. 9.05 8.85

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