Engineering Aids

Engineering Aids were put together to give our customers and our in-house personnel quick access to some of the important information needed in designing and fabricating parts. These list include charts accumulated from other sources and items tested in house using our tooling.

Some items may differ from other manufacturers, because of tooling capabilities and different installation methods.

Bend DeductionsA list of the bend deductions tested with our tooling.

The following information has been tested by Lehi Sheet Metal and may vary from other manufacturers.

Radius - Internal Radius
Bend Deduction - Amount subtracted per bend(coined/set bends)
Air Bend - Deduction for air bend
K-Factor - used for engineering programs, such as Pro-E

Colled Rolled Steel - CRS

Thk	Radius	Bend Deduction	Notes	Air Bend	K-Factor
.018	.030	.034			.5261
.020	.030	.039			.4417
.024	.030	.036		.047	.6599
.030	.015	.047			.4125
.030	.030	.047		.054	.5491
.030	.060	.067			.3979
.030	.187	.122			.3875
.036	.030	.054			.546
.036	.090	.085			.4532
.040	.030	.065			.4437
.040	.060	.075			.4035
.048	.030	.072		.078	.4891
.048	.060	.088			.4477
.048	.090	.101			.4460
.048	.202	.151			.4204
.060	.030	.088		.103	.4762
.060	.045	.095			.4702
.060	.060	.106			.4218
.060	.375	.232
.060	1.000	.510			.4160
.074	.030	.112		.125	.4318
.090	.030	.131		.147	.4377
.090	.125	.172			.4361
.104	.030	.151			.4277
.120	.030	.180		.205	.3866
.134	.030	.201			.3795
.175	.030	.270
.178	.015		3/4 DIE	.280
.187	.030	.280	1.50 DIE	.318
.187	.030	-	1.25 DIE	.300
.187	.060	.305			.3226

Galvanneal/Galvanized Steel

Thk	Radius	Bend Deduction
.030	.030	.051
.036	.030	.058
.048	.030	.076
.048	.060	.092
.060	.030	.092
.060	.060	.110
.074	.030	.116
.090	.030	.135
.104	.030	.155
.120	.030	.185
.134	.030	.205

Aluminum

Thk	Radius	Bend Deduction	Air Bend	K-Factor
.025	.030	.038		.6335
.032	.030	.049	.058	.5067
.032	.060	.068	.068	.3767
.032	.125	.094		.4170
.040	.030	.063	.065
.050	.030	.077	.082	.4568
.062	.030	.094	.104	.4403
.062	.060	.104	.108	.4430
.062	.125	.135
.062	.250	.190		.3958
.062	.375	.244		.3921
.062	.900	.4593		.4985
.080	.030	.122	.128
.080	.060		.130
.090	.030	.134	.142
.090	.060		.151
.090	.090	.161		.4076
.090	.125	.175		.4149
.090	.250	.242		.4393
.090	.500	.336		.4145
.100	.030	.151	.159	.3939
.100	.060		.170
.100	.090	.172		.4408
.125	.030	.188	.200	.3813
.125	.060		.204
.125	.125	.216		.4464
.125	.250	.266		.4650
.187	.030	.280		.3638
.187	.250	.350		.4470

Stainless Steel

Thk	Radius	Bend Deduction	Notes	Air Bend	K-Factor
.030	.030	.049		.058	.5067
.030	.060	.068		.068	.3767
.030	.125	.094			.4170
.036	.030	.058
.048	.030	.077		.082	.4228
.048	.090	.103			.4536
.060	.030	.094	3/8"	.105
.060	.375	.244			.3921
.075	.030	.120	3/8"	.129	.3639
.075	.030	-	1/2"	.137	-
.090	.030	.142		152
.105	.030	.162			.3691
.120	.030	.184		.210

Brass

Thk	Radius	Bend Deduction	Notes	Air Bend	K-Factor
.016	.030	.026			.7511

Aluminum (Specials)

Thk	Radius	Bend Deduction	Notes	Air Bend	K-Factor
.050	.030	.040	.022 HEM O.S.		.6605
.062	.030	.075	.026 HEM O.S.		.6353

Stainless Steel (Specials)

Thk	Radius	Bend Deduction	Notes	K-Factor
.060	.030	.075	.026 HEM O.S.	.6353
.095	.030	.156	30/60 DIES
.095	.030	.148
.105	.030	.180	AIRBEND	.2600
.187	.030	.346	AIRBEND 1.5 DIE

CRS (Specials)

Thk	Radius	Bend Deduction	Notes	K-Factor
.036	.030	.044	.016 HEM O.S.	.7228
.048	.030	.078	AIRBEND	.4098
.060	.030	.055	1 STOCK OFFSET	.8263
.060	.030	.073	.026 HEM O.S.	.6353

CRS and Galvanneal

Material	Offset	Dies	Add	Approx. Angle	Notes
.036	.15	.187	.063	60
.036	.036	.125	.008	25
.048	.048	.125	.010	40
.048	.060	.125	.013	40
.048	.150	.187	.065	64
.048	.250	.250	.065	90
.060	.070		.012		*Euro Tooling
.060	.100	.125	.031	67
.060	.187	.187	.125	90
.060	.218	.218	.155	90
.074	.187	.187	.097	90
.074	.190	.200	.097	83
.074	.238	.250	.145	85
.074	.250	.250	.162	90
.090	.112	.187	.032	60

Aluminum

Material	Offset	Dies	Add	Approx. Angle
.030	.100	.125	.045	65
.062	.160	.187	.076	80
.062	.190	.187	.107	90
.062	.250	.250	.180	90
.090	.187	.250	.070	60

Stainless Steel

Material	Offset	Dies	Add	B.D.	Approx. Angle	Notes
.075	.500	.500	.392		90

Hems

Material	Gap	Add	Subtract	Notes
.036	.070	.013

Tonnage Formula

Material	Toyokoki (125 tons) Formula	Notes
ALUM	stock thickness x 600 = Tons/ft
CRS	stock thickness x 650 = Tons/ft
St. Stl.	stock thickness x 900 = Tons/ft

Material	Mechanical (150 tons) Formula	Notes
ALUM	stock thickness x 300 = Tons/ft
CRS	stock thickness x 350 = Tons/ft
St. Stl.	stock thickness x 400 = Tons/ft

Thickness	"A"	Bottom Die
.048	.247	1/4
.060	.284	1/4
.060	.324	5/16
.074	.425	3/8
.090	.435	3/8

Tap SizesPre-drill sizes for standard and roll form tapping.

Standard Tap Pre-Drill sizes

Standard		Metric
Tap Sizes	Pre-Tap	Tap Sizes	Pre-Tap
2-56	.070	M2 X .4	.063
4-40	.089	M2.5 X .45	.081
6-32	.109	M3 X .5	.098
8-32	.136	M4 X .7	.128
10-32	.161	M5 X .8	.166
10-24	.147	M6 X 1	.196
1/4-20	.203	M8 X 1.25	.265
1/4-28	.214	M10 X1.5	.332
5/16-18	.257	M12 X 1.75	.404
5/16-24	.272	M14 X 2	.469
3/8-16	.312	M16 X 2	.547
3/8-24	.332

Roll Form Tap Pre-Drill sizes

Standard		Metric
Tap Sizes	Pre-Tap	Tap Sizes	Pre-Tap
2-56	.078	M2 X .4	.072
4-40	.101	M2.5 X .45	.090
6-32	.125	M3 X .5	.110
8-32	.150	M4 X .7	.144
10-32	.175	M5 X .8	.183
10-24	.172
1/4-20	.218

Pem ChartInstallation sizes for the most commonly used Pem hardware.

Quick List of Standard Pem Hardware Installation Sizes

Pem nut installation sizes
Prefix- (S)Steel - (CLS)Stainless Steel

Standard			Metric
S-256-X	2-56	.166	S-M2-X	M2	.166
S-440-X	4-40	.166	S-M2.5-X	M2.5	.166
S-632-X	6-32	.187	S-M3-X	M3	.166
S-832-X	8-32	.214	S-M3.5-X	M3.5	.187
SS-032-X	10-32	.250	S-M4-X	M4	.214
SS-024-X	10-24	.250	S-M5-X	M5	.250
S-0420-X	1/4-20	.343	S-M6-X	M6	.343
S-0428-X	1/4-28	.343	S-M8-X	M8	.413
S-0518-X	5/16-18	.413
S-0524-X	5/16-24	.413
S-0616-X	3/8-16	.500
S-0624-X	3/8-24	.500

Pem stud installation sizes
Prefix- (FH)Steel - (FHS)Stainless Steel

Standard			Metric
FH-256-X	2-56	.085	FH-M2.5-X	M2.5	098
FH-440-X	4-40	.113	FH-M3-X	M3	.120
FH-632-X	6-32	.139	FH-M3.5-X	M3.5	.140
FH-832-X	8-32	.164	FH-M4-X	M4	.156
FH-032-X	10-32	.190	FH-M5-X	M5	.197
FH-024-X	10-24	.190	FH-M6-X	M6	.236
FH-0420-X	1/4-20	.250	FH-M8-X	M8	.316
FH-0518-X	5/16-18	.312

Pem standoff installation sizes
Thru hole Prefix- (SO)Steel - (SOS)Stainless Steel
Blind hole Prefix- (BSO)Steel - (BSOS)Stainless Steel

Standard			Metric
SO-440-X	440	.166	SO-M3-X	M3	.166
SO-6440-X	6440	.214	SO-3.5M3-X	3.5M3	.214
SO-632-X	632	.214	SO-M4-X	M4	.281
SO-8632-X	8632	.281	SO-M5-X	M5	.281
SO-832-X	832	.281
SO-032-X	032	.281

Length chart for Standoffs

Standard		Metric suffix = length in mm
Suffix(-X)	length	Suffix(-X)	length
10	.312	3	3
12	.375	4	4
14	.437	6	6
16	.500	8	8
18	.562	10	10
20	.625	12	12
22	.687	14	14
24	.750	16	16
26	.812	18	18
28	.875	20	20
30	.937	22	22
32	1.00	25	25
34	1.062

Length chart for Studs

Standard		Metric suffix = length in mm
Suffix(-X)	length	Suffix(-X)	length
4	.250	6	6
5	.312	8	8
6	.375	10	10
8	.500	12	12
10	.625	15	15
12	.750	18	18
14	.875	20	20
16	1.00	25	25
20	1.25	30	30
24	1.50	35	35

Drill SizesChart for decimal equivalents of letter and number drills.

Decimal Equivalents of Drill Size

Number sizes		Letters
1	.2280	A	.234
2	.2210	B	.238
3	.2130	C	.242
4	.2090	D	.246
5	.2055	E	.250
6	.2040	F	.257
7	.2010	G	.261
8	.1990	H	.266
9	.1960	I	.272
10	.1935	J	.277
11	.1910	K	.281
12	.1890	L	.290
13	.1850	M	.295
14	.1820	N	.302
15	.1800	O	.316
16	.1770	P	.33
17	.1730	Q	.332
18	.1695	R	.339
19	.1660	S	.348
20	.1610	T	.358
21	.1590	U	.368
22	.1570	V	.377
23	.1540	W	.386
24	.1520	X	.397
25	.1495	Y	.404
26	.1470	Z	.413
27	.1440
28	.1405
29	.1360
30	.1285
31	.1200
32	.1160
33	.1130
34	.1110
35	.1100
36	.1065
37	.1040
38	.1015
39	.0995
40	0980
41	.0960
42	.0935
43	.0890
44	.0860
45	.0820
46	.0810
47	.0785
48	.0760
49	.0730
50	.0700
51	.0670
52	.0635
53	.0595
54	.0550
55	.0520
56	.0465
57	.0430
58	.0420
59	.0410
60	.0400
61	.0390
62	.0380
63	.0370
64	.0360
65	.0350
66	.0330
67	.0320
68	.0310
69	.0292
70	.0280
71	.0260
72	.0250
73	.0240
74	.0225
75	.0210
76	.0200
77	.0180
78	.0160
79	.0145
80	.0135

Material GaugesDecimal thickness for gauges of steel, aluminum and stainless steel sheet metal.

Decimal Equivalent to Material Gauges

Gauge	Steel	Alum
3	.2391	.2294
4	.2242	.2043
5	.2092	.1819
6	.1943	.1620
7	.1793	.1443
8	.1644	.1285
9	.1495	.1144
10	.1345	.1019
11	.1196	.0907
12	.1046	.0808
13	.0897	.0720
14	.0747	.0641
15	.0673	.0571
16	.0598	.0508
17	.0538	.0453
18	.0478	.0403
19	.0418	.0359
20	.0359	.0320
21	.0329	.0285
22	.0299	.0253
23	.0269	.0226
24	.0239	.0201
25	.0209	.0179
26	.0179	.0159
27	.0164	.0142
28	.0149	.0126
29	.0135	.0113
30	.0120	.0100
31	.0105	.0089
32	.0097	.0080
33	.0090	.0071
34	.0082	.0063
35	.0072	.0056

Screw DetailsSpecification for 82 deg screws, including countersink sizes, clearances and other details.

Details for 82 degree Screws

Size	Min. C'sink	Max C'sink	Tap dia	Tap Drill	Pre-tap Hole size	Clearance (tight)	C'Bore Socket Head Cap
0-80	.119	.128	.060	3/64	.047	.068	.109
1-64	.146	.158	.073	#53	.060	.080	.140
2-56	.172	.187	.086	#50	.070	.093	.156
3-48	.200	.210	.099	#47	.078	.106	.171
4-40	.225	.235	.112	#43	.089	.118	.203
5-40	.240	.255	.125	#38	.101	.132	.218
6-32	.279	.290	.138	#36	.106	.144	.234
8-32	.332	.345	.164	#29	.136	.171	.281
10-24	.385	.395	.190	#25	.149	.196	.328
10-32	.385	.395	.190	#21	.159	.196	.328
12-24	.438	.448	.216	#16	.180	.223	.363
12-32	.438	.448	.216	#13	.185	.223	.363
1/4-20	.507	.520	.250	#7	.201	.256	.414
1/4-20	.507	.520	.250	#3	.213	.256	.414
5/16-18	.635	.647	.312	F	.257	.319	.518
5/16-24	.635	.647	.312	I	.272	.319	.518
3/8-16	.762	.776	.375	5/16	.312	.382	.622
3/8-24	.762	.776	.375	Q	.332	.382	.622
7/16-14	.812	.824	.437	U	.368	.443	.625
7/16-20	.812	.824	.437	25/64	.391	.443	.625
1/2-13	.875	.890	.500	27/64	.422	.506	.750
1/2-20	.875	.890	.500	29/64	.453	.506	.750
9/16-12	1.000	1.015	.562	31/64	.484	.569	.812
9/16-18	1.000	1.015	.562	33/64	.516	.569	.812
5/8-11	1.125	1.14	.625	17/32	.531	.632	.875
5/8-18	1.125	1.140	.625	37/64	.578	.632	.875
3/4-10	1.375	1.390	.750	21/32	.656	.756	1.000
3/4-16	1.375	1.390	.750	11/16	.687	.756	1.000

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