2.75" × 6 TPI BUTT (pull type) External Thread Specifications

2.75-6 BUTT-2A · 2.7500-6 BUTT-2A

ASMESTD: ASME B1.9SOURCE: Table 3, Tables 1, 2, 5TYPE: External (bolt/screw)CLASS: 2AFLANKS 7° / 45°ROOT: roundTable 1 combination

Thread profile

2.75-6 BUTT-2A: solid = maximum material, dotted = minimum material, dashed = basic profile before the allowance. Flanks 7° (pressure) and 45° (clearance) from the radial line, 52° thread angle; drawn to scale.

Limits of size, class 2A

Dimension	Basic	Max	Min	Tolerance
Major diameter dCrest of the male thread, max = D − G	2.7500	2.7433	2.7333	0.0100
Pitch diameter EMax = D − h − G	2.6500	2.6433	2.6333	0.0100
Minor diameter KsRoot of the male thread; min is a reference value	2.5500	2.5224	2.4986ref.	0.0238ref.
Allowance GSpace below basic size; equals the Class 3 PD tolerance (Sec. 7)		0.0067
Root radius rRound root, male (Fig. 1a)		0.011902	0.005950
Thread engagement heh − G/2 at max, less the PD tolerance at min		0.096650	0.086650

Dimensions in inches. Values are those of the standard (ASME B1.9); calculated cells follow the standard’s formulas. Where the standard prints a value that differs from its formula, the printed value is shown with a note.

Mating female thread, limits of size, class 2B

Dimension	Basic	Max	Min	Tolerance
Major diameter DnRoot of the female thread, min = D + 0.12542p; max for reference	2.7500	2.7947ref.	2.7709
Pitch diameter EMin = D − h	2.6500	2.6600	2.6500	0.0100
Minor diameter KnCrest of the female thread, min = D − 2h	2.5500	2.5600	2.5500	0.0100
Root radius rRound root, female (Fig. 1a)		0.011902	0.005950

Lead, flank angle and length of engagement

Lead + flank variation limit Σ: 0.01000 inPitch diameter equivalent of lead and flank errors together (Class 2: the PD tolerance; Class 3: half)
Lead variation alone ±δl: 0.00561 inAllowable lead error if there is no flank error
45° flank angle variation alone ±δα: 3.158 °Half-angle error of the clearance flank
7° flank angle variation alone ±δα: 6.667 °Half-angle error of the pressure flank

Gaging Sections 10, 11 · Tables 6, 7, 8, 11

Male thread 2.75-6 BUTT-2A

Gage pitch tolerance (W): 0.00030 in
Gage 7° flank angle tolerance: 5 min
Gage 45° flank angle tolerance: 5 min
Gage major / minor tolerance: 0.0008 in
Gage pitch diameter tolerance: 0.00025 in
PD equivalent of pitch and flank tolerance: 0.0009 in
GO pitch diameter limit: 2.6433 in
NOT GO pitch diameter limit: 2.6333 in
NOT GO truncated crest diameter: 2.5750 in
Setting plug truncated major diameter: 2.7100 in
Best-size wire: 0.09025 · C = 0.13647 in, C
Maximum wire: 0.10239 · C = 0.17476 in, C

Female thread 2.75-6 BUTT-2B

Gage pitch tolerance (X): 0.00040 in
Gage flank angle tolerance: 5 min
Gage major / minor tolerance: 0.0008 in
Gage pitch diameter tolerance: 0.00050 in
PD equivalent of pitch and flank tolerance: 0.0011 in
GO pitch diameter limit: 2.6500 in
NOT GO pitch diameter limit: 2.6600 in
NOT GO truncated crest diameter: 2.7183 in
Plain gage tolerance: 0.00020 in
Root relief width GO: 0.027833 in
Root relief width NOT GO: 0.041667 in

Notes

Class 2: no taper/roundness requirement (para. 6.6.1).

Mates

2.75-6 BUTT-2A screws into a thread of the same standard at the same size and pitch. The standard mating internal thread is class 2B. Check the fit with the standard pair →

Working out the mating options…

Different pitch or a different thread family never mate; the fit check runs over both tolerance zones.

Related thread sizes

Same diameter other pitch, and neighbouring sizes

→ 2.75" × 10 TPI → 2.75" × 12 TPI → 2.75" × 16 TPI → 2.75" × 4 TPI → 2.75" × 5 TPI → 2.75" × 8 TPI → 2.5" × 8 TPI → 3" × 10 TPI → 2.75" × 6 TPI internal

All values for 2.75-6 BUTT-2Aevery column of the workbook row

All values of the workbook row 2.75-6 BUTT-2A
Designation	2.75-6 BUTT-2A
Decimal designation	2.7500-6 BUTT-2A
Threads per inch	6
Thread form	BUTT
Series (Table 1)	BUTT
Series name	Pull type, rounded root (default)
External / internal	External
Class	2A
Nominal size (in.)	2.75
Pitch P (in.)	0.16666667
Basic major dia D (in.)	2.7500
Size category	Table 1 combination
Source table	Table 3, Tables 1, 2, 5
Printed page	4, 5, 6, 10
Major dia max (in.)	2.7433
Major dia min (in.)	2.7333
Major dia tolerance (in.)	0.0100
Major dia status	Toleranced: D - G (max), minus the PD tolerance (min) (paras. 6.2, 7)
Allowance G (in.; internal: mating external value, reference)	0.0067
Tolerance range (Tables 3-5)	Over 2.5 thru 4
Range over (in.)	2.5
Range thru (in.)	4.0
Range mean dia for formula (in.)	3.250
Length of engagement Le = 10P (in.)	1.6667
Basic pitch dia E = D - h (in.)	2.6500
Pitch dia max (in.)	2.6433
Pitch dia min (in.)	2.6333
PD tolerance (in.)	0.0100
Basic minor dia K = D - 2h (in.)	2.5500
Minor dia max (in.)	2.5224
Minor dia min (in.)	2.4986
Minor dia tolerance (in.)	0.0238
Minor dia status	Max = D - 1.32542P - G; min is reference only = min PD - 0.80803P (para. 6.3, Sec. 4)
Root radius max (in.)	0.011902
Root radius min (in.)	0.005950
Root truncation s max (in.)	0.013767
Root truncation s min (in.)	0.006883
Engagement height he max (in.)	0.096650
Engagement height he min (in.)	0.086650
Lead + flank PD-equivalent limit (in.)	0.01000
Lead variation alone ± (in.)	0.00561
45° flank variation alone ± (deg)	3.158
7° flank variation alone ± (deg)	6.667
Lead angle at basic PD (deg)	1.1469
Lead angle (deg min)	1° 09′
Tensile stress area As (sq in.)	not given in the standard
Thread angle (deg)	52
Pressure (load) flank angle (deg)	7
Clearance flank angle (deg)	45
Flank orientation	Pull type (external thread pulls): 45° clearance flank leads, 7° load flank follows (Sec. 9)
Sharp V height H (in.)	0.148440
Basic thread engagement height h (in.)	0.100000
Thread height hs = hn (in.)	0.110452
Crest truncation f (in.)	0.024220
Crest width F (in.)	0.027193
Sweep cut: start diameter (in.)	2.743300
Sweep cut: tip diameter (in.)	2.522400
Sweep cut: depth (in.)	0.110452
Sweep cut: profile width at start diameter (in.)	0.139473
Sweep cut: tip width (root flat S max or radius r max) (in.)	0.011902
Constant c = 0.80803P (in.)	0.134672
PD tolerance component 0.00854√P (in.)	0.003486
W gage: pitch tolerance (in.)	0.00030
W gage: 7° flank tolerance (min)	5
W gage: 45° flank tolerance (min)	5
W gage: major/minor tolerance (in.)	0.0008
W gage: PD tolerance (in.)	0.00025
W gage: PD equivalent of pitch/flank tol. (in.)	0.0009
Z plain gage tolerance (in.)	0.00020
GO gage PD limit (in.)	2.6433
NOT GO gage PD limit (in.)	2.6333
NOT GO crest/minor truncated dia (in.)	2.5750
Setting plug truncated major dia (in.)	2.7100
Root relief width GO (0.167P) (in.)	0.027833
Root relief width NOT GO (0.25P) (in.)	0.041667
Best-size wire (in.)	0.09025
Measurement constant C, best wire (in.)	0.13647
Maximum wire (in.)	0.10239
Measurement constant C, max wire (in.)	0.17476
Check against formulas	OK
Notes	Class 2: no taper/roundness requirement (para. 6.6.1).

ASME B1.9: Buttress Inch Screw Threads. Source: workbook data (2026-10-10). Confirm against your licensed copy of the standard before use.