Machinery's Handbook, 31st Edition
Taps 977 with the letters “D” or “DU,” respectively, followed by a limit number. The limit number is determined as follows: D Limit number 0.0013 Tap PD Basic PD DU Limit number 0.0013 Basic PD Tap PD = − = − Example: M1.6 × 0.35 HS G D3 Maximumtap PD Basic PD 0.0039 1.6 0.64951904 0.35 0.0039 1.3727 0.039 1.412 Minimum tap PD Maximum tap PD 0.015 1.412 0.015 1.397 # = + = − + = + = = − = − = ^ h
M6 × 1 HS G DU4
Minimum tap PD Basic PD 0.052 = −
6 0.64951904 1.0 0.052 5.350 0.052 5.298 # − − ^ h
= −
= = =
Maximum tap PD Minimum tap PD 0.025 5.298 0.025 5.323 + = + =
Definitions of Tap Terms.— The definitions that follow are taken from ANSI/ASME B94.9 but include only the more important terms. Some tap terms are the same as screw thread terms; therefore, see Definitions of Screw Threads starting on page 1942 . Actual size: The measured size of an element on an individual part. Allowance: A prescribed difference between the maximum material limits of mating parts. It is the minimum clearance or maximum interference between such parts. Basic Size: The size from which the limits are derived by application of allowance and tolerance. Bottom Top: A tap having a chamfer length of 1 to 2 pitches. Chamfer: Tapering of the threads at the front end of each land or chaser of a tap by cut ting away and relieving the crest of the first few teeth to distribute the cutting action over several teeth. Chamfer Angle: Angle formed between the chamfer and the axis of the tap measured in an axial plane at the cutting edge. Chamfer Relief: The gradual degrees in land height from cutting edge to heel on the chamfered portion of the land to provide radial clearance for the cutting edge. Chamfer Relief Angle: Complement of the angle formed between a tangent to the relieved surface at the cutting edge and a radial line to the same point on the cutting edge. Classes of Thread: Designation of the class that determines the specification of the size, allowance, and tolerance to which a given threaded product is to be manufactured. It is not applicable to the tools used for threading. Concentric: Having a common center. Crest: The surface of the thread that joins the flanks of the thread and is farthest from the cylinder or cone from which the thread projects.
Copyright 2020, Industrial Press, Inc.
ebooks.industrialpress.com
Made with FlippingBook - Share PDF online