螺纹的大径中径小径表

技术资料>螺纹大径中径小径表

什么叫螺纹的大径中径小径，请参考这个动画：
左边黑色的代表内螺纹，注意，内螺纹的牙底=大径，内螺纹的牙顶=小径
右边红色的代表外螺纹，注意，外螺纹的牙底=小径，外螺纹的牙项=大径
至于中径，内螺纹外螺纹都一样，指它们的山腰中点的值，中径是一个理论值，是否真的存在中径，就像黑洞，理论上有，谁都没见过


以下是公制6g外螺纹的大径中径小径表：因时间关系英制螺纹外径中径小径暂未发布（2017年更新：美制部分已整理在本页了）

注意，这里所有数据都是理论数据，由于时间关系，它们的公差我没有标出来，而且这里有个别数据是错的（我是故意的），等某些网站把它抄的差不多了我再改过来不迟。但这不影响浏览者的查阅，如果你具有稍微的基础知识，自然会看出哪里不对并能领悟它真实的值

6g公制外螺纹（即常用螺丝）的大径中径小径表

单位：MM

外螺纹规格		大径（牙顶）	中径	小径（牙底）
公称直径	牙距
M1.4	0.3	1.4	1.21	1.07
M1.7	0.35	1.7	1.47	1.31
M2.0	0.4	2	1.74	1.56
M2.3	0.4	2.3	2.04	1.86
M2.5	0.45	2.5	2.21	2.00
M3.0	0.5	3	2.68	2.45
M3.5	0.6	3.5	3.11	2.84
M4.0	0.7	4	3.55	3.22
M4.5	0.75	4.5	4.01	3.67
M5.0	0.8	5	4.48	4.11
M6.0	1	6	5.35	4.89
M7.0	1	7	6.35	5.89
M8.0	1.25	8	7.19	6.62
M9.0	1.25	9	8.19	7.62
M10	1.5	10	9.03	8.34
M11	1.5	11	10.03	9.34
M12	1.75	12	10.86	10.06
M14	2	14	12.70	12.06
M16	2	16	14.70	13.79
M18	2.5	18	16.70	15.79
M20	2.5	20	18.38	17.23

6H公制内螺纹（即常用螺母）的大径中径小径表

接下来是公制6H内螺纹的大径中径小径表：
单位：MM。同样，个别数据是有误的，你懂的

内螺纹规格		大径（牙底）	中径		小径(牙顶)
公称直径	牙距		最大	最小	最大	最小
M1.4	0.3	1.40	1.28	1.205	1.142	1.075
M1.6	0.35	1.60	1.458	1.373	1.32	1.22
M2.0	0.4	2.00	1.83	1.740	1.679	1.567
M2.2	0.45	2.20	2.003	1.908	1.838	1.713
M2.5	0.45	2.50	2.303	2.303	2.138	2.013
M3.0	0.5	3.00	2.775	2.675	2.599	2.459
M3.5	0.6	3.50	3.222	3.110	3.01	2.85
M4.0	0.7	4.00	3.663	3.545	3.422	3.242
M4.5	0.75	4.50	4.131	4.013	3.878	3.688
M5.0	0.8	5.00	4.605	4.480	4.334	4.134
M6.0	1	6.00	5.5	5.350	5.153	4.917
M7.0	1	7.00	6.5	6.350	6.153	5.917
M8.0	1.25	8.00	7.348	7.188	6.912	6.647
M9.0	1.25	9.00	8.348	8.188	7.912	7.647
M10	1.5	10.00	9.206	9.026	8.676	8.376
M11	1.5	11.00	10.206	10.026	9.676	9.376
M12	1.75	12.00	11.063	10.863	10.441	10.106
M14	2	14.00	12.913	12.701	12.21	11.835
M16	2	16.00	14.913	14.701	14.21	13.835
M18	2	18.00	16.913	16.701	15.744	15.294
M20	2.5	20.00	18.6	18.376	17.744	17.294

常用美制外螺纹的大径中径小径表

下表中螺纹规格采用美制常用规范如4-40UNC，但其它尺寸统一采用的单位为公制毫米MM：

外螺纹规格	公差等级	大径（外径）		中径		小径
		Max	Min	Max	Min	Max
1-64UNC	2A	1.83896	1.74244	1.58242	1.53162	1.36652
	3A	1.8542	1.75768	1.59766	d	1.38176
1-72UNF	2A	1.83896	1.75006	1.61036	1.5621	1.41986
	3A	1.8542	1.7653	1.6256	1.59004	1.4351
2-56UNC	2A	2.16916	2.06502	1.87452	1.82118	1.63068
	3A	2.1844	2.08026	1.88976	1.84912	1.64592
2-64UNF	2A	2.16916	2.07264	1.91262	1.86182	1.69672
	3A	2.1844	2.08788	1.92786	1.88976	1.71196
3-48UNC	2A	2.49682	2.38252	2.15392	2.0955	1.86436
	3A	2.5146	2.4003	2.1717	2.12852	1.88214
3-56UNF	2A	2.49682	2.39268	2.20218	2.1463	1.95834
	3A	2.5146	2.41046	2.21996	2.17932	1.97612
4-40UNC	2A	2.82448	2.69494	2.413	2.3495	2.06756
	3A	2.8448	2.71526	2.43332	2.38506	2.08788
4-48UNF	2A	2.82702	2.71272	2.48412	2.42316	2.19456
	3A	2.8448	2.7305	2.5019	2.45618	2.21234
5-40UNC	2A	3.15468	3.02514	2.7432	2.67716	2.39776
	3A	3.175	3.04546	2.76352	2.71526	2.41808
5-44UNF	2A	3.15722	3.0353	2.7813	2.7178	2.46888
	3A	3.175	3.05308	2.79908	2.75082	2.48666
6-32UNC	2A	3.48488	3.33248	2.96926	2.89814	2.54
	3A	3.5052	3.3528	2.98958	2.93624	2.56032
6-40UNF	2A	3.48488	3.35534	3.0734	3.00736	2.72796
	3A	3.5052	3.37566	3.09372	3.04292	2.74828
8-32UNC	2A	4.14274	3.99034	3.62712	3.55346	3.19786
	3A	4.1656	4.0132	3.64998	3.5941	3.22072
8-36UNF	2A	4.14528	4.00558	3.68808	3.61696	3.30454
	3A	4.1656	4.0259	3.7084	3.65506	3.32486
10-24UNC	2A	4.8006	4.61772	4.11226	4.02844	3.54076
	3A	4.826	4.64312	4.13766	4.07416	3.56616
10-32UNF	2A	4.80314	4.65074	4.28752	4.21132	3.85826
	3A	4.826	4.6736	4.31038	4.25196	3.88112
12-24UNC	2A	5.461	5.27812	4.77266	4.6863	4.20116
	3A	5.4864	5.30352	4.79806	4.73202	4.22656
12-28UNF	2A	5.461	5.2959	4.87172	4.79044	4.37896
	3A	5.4864	5.3213	4.89712	4.83616	4.40436
1/4-20UNC	1A	6.32206	6.01218	5.49656	5.35432	4.81076
	2A	6.32206	6.11632	5.49656	5.40258	4.81076
	3A	6.35	6.14426	5.5245	5.45338	4.8387
1/4-28UNF	1A	6.3246	6.07568	5.73532	5.60832	5.24256
	2A	6.3246	6.1595	5.73532	5.6515	5.24256
	3A	6.35	6.1849	5.76072	5.69722	5.26796
5/16-18UNC	1A	7.90702	7.57428	6.99008	6.83514	6.22808
	2A	7.90702	7.68604	6.99008	6.88848	6.22808
	3A	7.9375	7.71652	7.02056	6.94436	6.25856
5/16-24	1A	79095.6	7.63524	7.22122	7.08152	6.64972
	2A	7.90956	7.72668	7.22122	7.12724	6.64972
	3A	7.9375	7.75462	7.24916	7.18058	6.67766
3/8-16UNC	1A	9.49198	9.1313	8.46074	8.29564	7.59968
	2A	9.49198	9.25322	8.46074	8.34898	7.59968
	3A	9.525	9.28624	8.49376	8.40994	7.6327
3/8-24UNF	1A	9.49706	9.22274	8.80872	8.66394	8.23722
	2A	9.49706	9.31418	8.80872	8.7122	8.23722
	3A	9.525	9.34212	8.83666	8.763	8.26516
7/16-14UNC	1A	11.07694	10.68324	9.89838	9.71804	8.91794
	2A	11.07694	10.81532	9.89838	9.779	8.91794
	3A	11.1125	10.85088	9.93394	9.84504	8.9535
7/16-20UNF	1A	11.07948	10.7696	10.93978	10.0965	9.56818
	2A	11.07948	10.87374	10.93978	10.1473	9.56818
	3A	11.1125	10.90676	10.3124	10.20826	9.6012
1/2-13UNC	1A	12.6619	12.24788	11.3919	11.20394	10.25906
	2A	12.6619	12.38504	11.3919	11.2649	10.33526
	3A	12.7	12.42314	11.43	11.33602	10.37336
1/2-20UNF	1A	12.66698	12.3571	11.84148	11.67892	12.52728
	2A	12.66698	12.46124	11.84148	11.73226	12.52728
	3A	12.7	12.49426	11.8745	11.79322	11.19124
9/16-12UNC	1A	14.24686	13.80998	12.87272	12.6746	11.72718
	2A	14.24686	13.9573	12.87272	12.74064	11.72718
	3A	14.2875	13.99794	12.91336	12.8143	11.76782
9/16-18UNF	1A	14.25194	13.9192	13.335	13.16228	12.573
	2A	14.259814	14.03096	13.335	13.2207	12.573
	3A	14.2875	14.06652	13.37056	13.2842	12.60856
5/8-11UNC	1A	15.83436	15.37208	14.33576	14.12494	13.08608
	2A	15.83436	15.52702	14.33576	14.19606	13.08608
	3A	15.875	15.56766	14.3764	14.27226	13.12672
5/8-18UNF	1A	15.83944	15.5067	14.9225	14.7447	14.1605
	2A	15.83944	15.61846	14.9225	14.80312	14.1605
	3A	15.875	15.60322	14.95806	14.86916	14.19606
3/4-10UNC	1A	19.00428	18.51152	17.35328	17.12976	15.97914
	2A	19.00428	18.67662	17.35328	17.20342	15.97914
	3A	19.05	18.72234	17.399	17.28724	16.02486
3/4-16UNF	1A	19.0119	18.65122	17.98066	17.79016	17.1196
	2A	19.0119	18.77314	17.98066	17.85366	17.1196
	3A	19.05	18.81124	18.01876	17.92224	17.1577
7/8-9UNC	1A	22.17674	21.64842	20.34286	20.10156	18.81632
	2A	22.17674	21.82368	20.34286	20.18284	18.81632
	3A	22.225	21.87194	20.39112	20.27174	18.86458
7/8-14UNF	1A	22.18436	21.79066	21.0058	20.80006	20.02536
	2A	22.18436	21.92274	21.0058	20.86864	20.02536
	3A	22.225	21.96338	21.04644	20.9423	20.066
1-8UNC	1A	25.3492	24.7777	23.28672	23.03018	21.56968
	2A	25.3492	24.9682	23.28672	23.114	21.56968
	3A	25.4	25.019	23.33752	23.20798	21.62048
1-14UNF	1A	25.35682	24.96566	24.17826	23.9649	23.19528
	2A	25.35682	25.0952	24.17826	24.03602	23.19528
	3A	25.4	25.13838	24.22144	24.11476	23.23846

美制内螺纹的大、中、小径

下表螺纹规格为美制规范,如2-56UNC，但尺寸为公制单位毫米：

内螺纹规格	大径（外径）	中径		小径（底径）
	Min	Min	Max	Min	Max
1-64UNC	1.8542	1.59766	1.6637	1.42494	1.58242
	1.8542	1.59766	1.64592	1.42494	1.58242
1-72UNF	1.8542	1.6256	1.6891	1.4732	1.6129
	1.8542	1.6256	1.67386	1.4732	1.6129
2-56UNC	2.1844	1.88976	1.96088	1.69418	1.87198
	2.1844	1.88976	1.9431	1.69418	1.87198
2-64UNF	2.1844	1.92786	1.99644	1.75514	1.91262
	2.1844	1.92786	1.97866	1.75514	1.91262
3-48UNC	2.5146	2.1717	2.2479	1.94056	2.1463
	2.5146	2.1717	2.22758	1.94056	2.1463
3-56UNF	2.5146	2.21996	2.29108	2.02438	2.1971
	2.5146	2.21996	2.2733	2.02438	2.1971
4-40UNC	2.8448	2.43332	2.51714	2.15646	2.38506
	2.8448	2.43332	2.49428	2.15646	2.38506
4-48UNF	2.8448	2.5019	2.58064	2.27076	2.45872
	2.8448	2.5019	2.56032	2.27076	2.45872
5-40UNC	3.175	2.76352	2.84734	2.48666	2.69748
	3.175	2.76352	2.82702	2.48666	2.69748
5-44UNF	3.175	2.79908	2.88036	2.55016	2.74066
	3.175	2.54508	2.86004	2.55016	2.74066
6-32UNC	3.5052	2.98958	3.08356	2.6416	2.8956
	3.5052	2.98958	3.05816	2.6416	2.8956
6-40UNF	3.5052	3.09372	3.18008	2.8194	3.0226
	3.5052	3.09372	3.15722	2.8194	3.01244
8-32UNC	4.1656	3.64998	3.7465	3.302	3.5306
	4.1656	3.64998	3.7211	3.302	3.52806
8-36UNF	4.1656	3.7084	3.79984	3.4036	3.6068
	4.1656	3.7084	3.77698	3.4036	3.59664
10-24UNC	4.826	4.13766	4.24688	3.683	3.9624
	4.826	4.13766	4.21894	3.683	3.9497
10-32UNF	4.826	4.31038	4.40944	3.9624	4.1656
	4.826	4.31038	4.38404	3.9624	4.16814
12-24UNC	5.4864	4.79806	4.90982	4.3434	4.5974
	5.4864	4.79806	4.88188	4.3434	4.58978
12-28UNF	5.4864	4.89712	5.0038	4.4958	4.7244
	5.4864	4.89712	4.97586	4.4958	4.71678
1/4-20UNC	6.35	5.5245	5.70992	4.9784	5.2578
	6.35	5.5245	5.64896	4.9784	5.2578
	6.35	5.5245	5.61594	4.9784	5.25018
1/4-28UNF	6.35	5.76072	5.92582	5.3594	5.588
	6.35	6.82752	5.86994	5.3594	5.588
	6.35	6.82752	5.842	5.3594	5.5626
5/16-18UNC	7.9375	7.02056	7.22122	6.4008	6.731
	7.9375	7.02056	7.15518	6.4008	6.731
	7.9375	7.02056	7.11962	6.4008	6.6802
5/16-24	7.9375	7.24916	7.4295	6.7818	7.0358
	7.9375	7.24916	7.37108	6.7818	7.0358
	7.9375	7.24916	7.3406	6.7818	6.99516
3/8-16UNC	9.525	8.49376	8.70966	7.7978	8.1534
	9.525	8.49376	8.63854	7.7978	8.1534
	9.525	8.49376	8.60298	7.7978	8.08228
3/8-24UNF	9.525	8.83666	8.83666	8.382	8.636
	9.525	8.83666	8.96112	8.382	8.636
	9.525	8.83666	8.513064	8.382	9.4488
7/16-14UNC	11.1125	9.93394	10.16762	9.144	9.5504
	11.1125	9.93394	10.08888	9.144	9.5504
	11.1125	9.93394	10.05078	9.144	9.44118
7/16-20UNF	11.06678	10.287	10.49274	9.7282	10.033
	11.06678	10.287	10.42416	9.7282	10.033
	11.06678	10.287	10.39114	9.7282	9.94664
1/2-13UNC	12.7	11.43	11.67638	10.5918	11.0236
	12.7	11.43	11.5951	10.5918	11.0236
	12.7	11.43	11.55192	10.5918	10.88136
1/2-20UNF	12.7	11.8745	12.08786	11.3284	11.6078
	12.7	11.8745	12.01674	11.3284	11.6078
	12.7	11.8745	11.98118	11.3284	11.52398
9/16-12UNC	14.2875	12.91336	13.17244	11.9888	12.446
	14.2875	12.91336	14.008608	11.9888	12.446
	14.2875	12.91336	13.04544	11.9888	12.30122
9/16-18UNF	14.2875	13.37056	13.59662	12.7508	13.081
	14.2875	13.37056	13.52042	12.7508	13.081
	14.2875	13.37056	13.48232	12.7508	12.96924
5/8-11UNC	15.875	14.3764	14.64818	13.3858	13.8684
	15.875	14.3764	14.55928	13.3858	13.8684
	15.875	14.3764	14.51356	13.3858	13.69314
5/8-18UNF	15.875	14.95806	15.1892	14.351	14.6812
	15.875	14.95806	15.11046	14.351	14.6812
	15.875	14.95806	15.07236	14.351	14.5542
3/4-10UNC	19.05	17.399	17.6911	16.3068	16.8402
	19.05	17.399	17.59458	16.3068	16.8402
	19.05	17.399	17.54378	16.3068	16.6243
3/4-16UNF	19.05	18.01876	18.26768	17.3228	17.6784
	19.05	18.01876	18.18386	17.3228	17.6784
	19.05	18.01876	18.14322	17.3228	17.54632
7/8-9UNC	22.225	20.84832	20.70354	19.177	19.7612
	22.225	20.84832	20.5994	19.177	19.7612
	22.225	20.84832	20.54606	19.177	19.50974
7/8-14UNF	22.225	21.04644	21.31568	20.2692	20.6756
	22.225	21.04644	21.22424	20.2692	20.6756
	22.225	21.04644	21.18106	20.2692	20.49272
1-8UNC	25.4	23.33752	23.6728	21.971	22.606
	25.4	23.33752	23.56104	21.971	22.606
	25.4	23.33752	23.50516	21.971	22.34438
1-14UNF	25.4	24.22144	24.4983	23.4442	23.8252
	25.4	24.22144	24.40686	23.4442	23.8252
	25.4	24.22144	24.3586	23.4442	23.6601