Ace Hardware Hafele 030.06.166 Insert Nut, Type E, Zinc Plated, 1/4-20 X 13mm Length

• UNC – Unified National Coarse Thread - comparable with the ISO metric thread
• UNF – Unified National Fine Thread

• Female person and Male UNC/UNF threads are both parallel
• The UNC/UNF flank angle is 60°

Unified threads comes in three dissimilar classes:

1. for applications where a liberal tolerance is required to permit easy assembly even with slightly nicked threads
2. most commonly used class for general applications
3. for applications where closeness of fit and/or accuracy of thread elements are of import

UNC - Unified Coarse Threads

UNC threads according ANSI B1.ane:

Major Diameter (in)	Threads per inch (tpi)	Major Diameter		Tap Drill Size (mm)	Pitch (mm)
		(in)	(mm)
#1 - 64	64	0.073	i.854	1.fifty	0.397
#2 - 56	56	0.086	ii.184	1.eighty	0.453
#3 - 48	48	0.099	2.515	two.10	0.529
#4 - twoscore	xl	0.112	two.845	2.35	0.635
#5 - 40	40	0.125	3.175	2.65	0.635
#half-dozen - 32	32	0.138	3.505	ii.85	0.794
#viii - 32	32	0.164	4.166	iii.50	0.794
#10 - 24	24	0.190	iv.826	4.00	1.058
#12 - 24	24	0.216	5.486	4.65	i.058
one/iv" - 20	20	0.250	half dozen.350	5.35	i.270
5/sixteen" - xviii	eighteen	0.313	7.938	6.80	1.411
3/8" - sixteen	16	0.375	9.525	8.25	1.587
seven/16" - 14	fourteen	0.438	xi.112	ix.65	1.814
1/ii" - 13	13	0.500	12.700	11.15	1.954
9/16" - 12	12	0.563	fourteen.288	12.60	ii.117
5/viii" - 11	xi	0.625	fifteen.875	14.05	2.309
three/4" - 10	ten	0.750	xix.050	17.00	2.540
7/8" - nine	9	0.875	22.225	20.00	2.822
1" - 8	8	i.000	25.400	22.85	3.175
1 1/8" - 7	7	1.125	28.575	25.65	three.628
1 1/4" - vii	7	1.250	31.750	28.85	iii.628
ane iii/8" - half dozen	6	one.375	34.925	31.55	4.233
1 one/2" - vi	6	1.500	38.100	34.70	4.233
i iii/4" - five	5	one.750	44.450	40.xl	5.080
2" - iv 1/2	4 1/two	2.000	50.800	46.xxx	5.644
2 1/4" - 4 1/2	4 1/2	two.250	57.150	52.65	v.644
2 one/two" - four	4	2.500	63.500	58.50	six.350
2 iii/4" - 4	4	2.750	69.850	64.75	6.350
3" - four	4	3.000	76.200	71.10	half dozen.350
3 1/4" - 4	4	3.250	82.550	77.45	6.350
3 1/ii" - four	4	3.500	88.900	83.lxxx	6.350
3 3/iv" - 4	four	3.750	95.250	90.15	6.350
iv" - 4	four	4.000	101.600	96.l	six.350

Example - Typical designation of an UNC thread

• 1/4" 10 20 UNC

• US Bolts - Tightening Torques

UNF - Unified National Fine Threads

UNF threads ANSI B1.1:

Major Diameter (in)	Threads per inch (tpi)	Major Diameter		Tap Drill Size (mm)	Pitch (mm)
		(in)	(mm)
#0 - lxxx	80	0.060	1.524	1.25	0.317
#1 - 72	72	0.073	1.854	1.55	0.353
#ii - 64	64	0.086	2.184	1.90	0.397
#iii - 56	56	0.099	2.515	2.15	0.453
#iv - 48	48	0.112	2.845	2.40	0.529
#five - 44	44	0.125	3.175	two.70	0.577
#half-dozen - 40	40	0.138	3.505	2.95	0.635
#8 - 36	36	0.164	4.166	3.50	0.705
#x - 32	32	0.190	4.826	iv.10	0.794
#12 - 28	28	0.216	five.486	4.seventy	0.907
i/4" - 28	28	0.250	6.350	5.50	0.907
5/16" - 24	24	0.313	seven.938	half-dozen.90	i.058
3/8" - 24	24	0.375	ix.525	8.50	1.058
7/16" - xx	xx	0.438	xi.112	9.90	1.270
i/two" - 20	twenty	0.500	12.700	11.50	1.270
9/16" - eighteen	18	0.563	fourteen.288	12.90	1.411
5/8" - 18	18	0.625	15.875	14.50	1.411
3/4" - 16	16	0.750	19.050	17.50	one.587
7/8" - 14	fourteen	0.875	22.225	20.twoscore	1.814
1" - 12	12	1.000	25.400	23.25	2.117
ane one/8" - 12	12	1.125	28.575	26.50	two.117
1 1/4" - 12	12	one.250	31.750	29.50	2.117
1 3/8" - 12	12	1.375	34.925	32.75	2.117
1 i/2" - 12	12	1.500	38.100	36.00	2.117

Example - Typical designation of an UNF thread

• 1/2" x twenty UNF

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