FASTENERS Metric Bolts & Screws 5
REFERENCE CHART — DETERMINING THREAD LENGTHS METRIC
There is a formula for calculating minimum length on threads on any given metric cap screw. It is as follows: Minimum thread length equals twice the basic thread diameter plus 6mm for screw lengths up to 125 mm long, twice the basic thread diameter plus 12 mm for screw lengths between 125 mm and 200 mm long, and twice the basic thread diameter plus 25 mm for screw lengths over 200 mm long.
1
LENGTH STANDARDS FOR FULL OR PARTIAL THREADS
M4
M5
M6
M7
M8
M10
Capscrew Diameter
25
30
30
30
35
40
Fully Threaded Max. Length*
M12
M14
M16
M18
M20
M24
Capscrew Diameter
45
50
55
60
65
75
Fully Threaded Max. Length*
*These lengths and longer = partially threaded
REFERENCE CHART — METRIC
THREAD
LENGTH
Metric mm
Inch Approx.
Pitch mm
Metric mm
Inch Approx.
Metric mm
Inch Approx.
1
3/64”
0.25
1
3/64”
70
2-3/4”
1.2
3/64”
0.25
1.5
1/16”
75
3”
1.4
0.3
2
5/64”
80
3-3/16”
1.6
1/16”
0.35
2.5
3/32”
85
3-3/8”
2
5/64”
0.4
3
1/8”
90
3-1/2”
2.2
5/64”
0.45
4
5/32”
100
4”
2.3
3/32”
0.45
5
3/16”
110
4-3/8”
2.5
3/32”
0.45
6
1/4”
120
4-3/4”
2.6
0.45
6.5
1/4”
130
5”
3
1/8”
0.5
8
5/16”
140
5-1/2”
3.5
9/64”
0.6
9.5
3/8”
150
6”
4
5/32”
0.7
10
3/8”
160
6-1/4”
5
3/16”
0.8
12
1/2”
170
6-3/4”
6
1/4”
1
13
1/2”
180
7”
7
9/32”
1
14
9/16”
190
7-1/2”
8
5/16”
1.25
16
5/8”
200
8”
10
3/8”
1.5
18
11/16”
220
8-3/4”
12
1/2”
1.75
19
3/4”
240
9-9/16
14
9/16”
2
20
3/4”
260
10-1/4”
16
5/8”
2
22
7/8”
270
10-3/4”
18
11/16”
2.5
25
1”
280
11”
20
3/4”
2.5
30
1-3/16”
300
12”
22
7/8”
2.5
32
1-1/4”
320
12-1/2”
24
1”
3
35
1-3/8”
340
13-1/2”
27
1-1/16”
3
36
1-7/16”
360
14-1/4”
30
1-3/16”
3.5
38
1-1/2”
380
15”
33
1-5/16”
3.5
40
1-9/16”
400
15-3/4”
36
1-7/16”
4
45
1-3/4”
420
16-1/2”
39
1-1/2”
4
50
2”
440
17-3/8”
42
1-5/8”
4.5
55
2-3/16”
460
18”
45
1-3/4”
4.5
60
2-3/8”
480
19”
48
1-7/8”
5
65
2-9/16”
500
20”
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