Machinery's Handbook, 31st Edition
2064
Centralizing Acme Screw Threads Table 6. American National Standard Centralizing Acme Screw Thread Form— Basic Dimensions ANSI/ASME B1.5-1997 (R2014)
45-Deg Chamfer Crest of External Threads
Max Fillet Radius, Root of Tapped
Fillet Radius at Min or Diameter of Screws Max (All) 0.10 P
Total Height of Thread (All External Threads) h s = h + 1 ∕ 2 allowance a
Thread Thickness (Basic), t = P /2 0.03125 0.03571 0.04167 0.05000 0.06250 0.08333 0.10000
Min Width of Chamfer Flat, 0.0707 P
Height of Thread (Basic), h = P /2 0.03125 0.03571 0.04167 0.05000 0.06250 0.08333 0.10000 0.12500 0.16667 0.20000 0.25000 0.33333 0.37500 0.50000
Thds per Inch, n
Min Depth, 0.05 P 0.0031 0.0036 0.0042 0.0050 0.0062 0.0083 0.0100 0.0125 0.0167 0.0200 0.0250 0.0330 0.0380 0.0500
Hole, 0.06 P 0.0038 0.0038 0.0050 0.0060 0.0075 0.0100 0.0120 0.0150 0.0200 0.0240 0.0300 0.0400 0.0450 0.0600
Pitch, P
16 14 12 10
0.06250 0.07143 0.08333 0.10000 0.12500 0.16667 0.20000 0.25000 0.33333 0.40000 0.50000 0.66667 0.75000 1.00000
0.0362 0.0407 0.0467 0.0600 0.0725 0.0933 0.1100 0.1350 0.1767 0.2100 0.2600 0.3433 0.3850 0.5100
0.0044 0.0050 0.0059 0.0071 0.0088 0.0119 0.0141 0.0177 0.0236 0.0283 0.0354 0.0471 0.0530 0.0707
0.0062 0.0071 0.0083 0.0100 0.0125 0.0167 0.0200 0.0250 0.0333 0.0400 0.0500 0.0667 0.0750 0.1000
8 6 5 4 3
0.12500 0.16667 0.20000 0.25000 0.33333 0.37500 0.50000
2 1 ∕ 2
2
1 1 ∕ 2 1 1 ∕ 3
1
All dimensions in inches. See Fig. 3. a Allowance is 0.020 inch for 10 or less threads per inch and 0.010 inch for more than 10 threads per inch.
Internal Thread
One-half allowance on major diameter– Internal
2 α
F rn
α
α
Basic pitch line
F cs
P /4
t = 0.5 P
h
t = 0.5 P
F cn
P /4
One-half allowance on minor diameter– External
One-half allowance on minor diameter– Internal
F rs
One-half allowance on pitch diameter– External
P
External Thread
Fig. 3. Centralizing Acme Screw Thread Form Basic Diameters: The maximum major diameter of the external thread is basic and is the nominal major diameter for all classes.
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