Ifno fit is indicated, the default class fit is 2A for internal threads, and 2B for external threads. Unified threads in practice. Here are some examples for your handy reference: 0.250 - 20UNC - 2A MOD. 1/4" x 20 UNC #4-20 UNC. 0.375 - 24UNEF - 2B. 10-32 UNF-2A. 0.190-32 UNF-2A. Let’s break down these examples by each parameter of the call-out.
UNJvs. UN UNJS vs. UNS UNJC vs. UNC UNJF vs. UNF UNJEF vs. UNEF. WHERE The J series thread is defined in specification ANSI/ASME SAE AS8879 (formerly MIL-S-8879) and in ANSI/ASME B1.15.WHY The rounded root of a UNJ external thread greatly improves fatigue strength over that of a flat root UN thread.
38 - 24 UNF : Basic Thread Dimensions (Pitch, minor & major diameters, depth, lead), Tolerance range for all applicable classes and much more. 3/8 - 24 UNF 2A (External) * Permisable values for thread Class 2A # Description Value (Inch) Value (mm) es: Allowance: 0.0011 (Ref) 0.028 (Ref) d:
TapDrill Sizes for 5/16 - 32 UNEF. If not specified, assume a thread depth of 75%. You can learn more about thread depth in tapping here. To get the tap drill size in other depths, use our Tap Drill Size Calculator . Thread Depth. Tap
a For Class 2A threads with coating (plating) the max. is increased by the allowance, to the basic size. This is the same value as Class 3A. b) For uncoated hot-rolled, but not standard fasteners with cold rolled threads. c) UN series external thread, Max. Diameter, allows for Class 1A and 2A and basic for Class 3A.
1- 20 UNEF : Basic Thread Dimensions (Pitch, minor & major diameters, depth, lead), Tolerance range for all applicable classes and much more External Threads. 2A, 3A. Internal Threads. 2B, 3B. 0.033 (Ref) d: Major Diameter: 0.9906 - 0.9987: 25.161 - 25.367: d 2: Pitch Diameter: 0.9619 - 0.9662: 24.432 - 24.541: d 3: Minor Diameter (UNR
. 290 40 220 327 77 388 4 269 272
3 8 24 unf 2a thread dimensions
