Technical Information
TopThread ™
The following charts list the largest thread pitch that can be applied on
internal applications using TopThread threading inserts for 60° V-threading
and Acme threading.
minimum minor diameter
(minimum bore)
nominal thread
size
(maximum
diameter)
Metric-sized 60° V-Threading Limits Acme Threading Limits
internal threading limitations
NT-1, NT-2 60° V-threading inserts internal threading limitations
NA and NAS-2, -3, -4, and -6 Acme threading inserts
minimum
thread diameter (mm)
nominal
thread size
minimum
thread diameter (mm)
TPI NT-1 NT-2 NT-1 NT-2 TPI NT-1 NT-1 NT-2
4,00
3,00
2,50
2,00
1,75
1,50
1,25
1,00*
0,75 M48 x 4.00
M42 x 3.00
M39 x 2.50
M33 x 2.00
M32 x 1.75
M32 x 1.50
M29 x 1.29
M27 x 1.00
M22 x 0.75 –
–
M24 x 2,50
M15 x 2,00
M15 x 1,75
M15 x 1,50
M14 x 1,25
M14 x 1,00
M12 x 0,75 43,67
38,75
36,29
30,84
30,11
30,38
27,65
25,92
21,19 –
–
21,29
12,84
13,11
13,38
12,65
12,92
11,19 2**
2-1/2**
3**
4
5
6
8
10
12
14
16* 5
4-1/2
4
3-1/2
3
2-1/2
2-1/4
2
1-3/4
1-5/8
1-1/2 4.500
4.100
3.665
3.250
2.800
2.333
2.125
1.900
1.667
1.554
1.438 114.3
104.1
93.1
82.6
71.1
59.3
54.0
48.3
42.4
39.5
36.5
* Thread pitch of 1mm and less can be cut with an NT-2 insert provided the
core thread diameter is 25mm or larger (11mm or larger with NT-1).
* Sixteen threads per inch and fi ner can be cut provided minor diameter
is 36,5mm or larger.
**NA-6 insert only.
internal threading limitations
NT-3 and NT-4 60° V-threading inserts
TPI nominal
thread size minimum
thread diameter (mm)
6,00**
5,50**
5,00
4,00
3,00
2,50
2,00
1,75
1,50* M76 x 6.00
M73 x 5.50
M70 x 5.00
M64 x 4.00
M52 x 3.00
M48 x 2.50
M42 x 2.00
M40 x 1.75
M38 x 1.50 69,50
67,05
64,59
59,67
48,75
45,29
39,84
38,11
36,38
increase
clearance
Additional secondary clearance can be ground on leading edge of insert
to provide suffi cient helical clearance for machining coarser threads and
multiple start threads. Modifi ed standard inserts may be furnished for
machining threads outside of the limits shown.
* Thread pitch of 1,5mm and less can be cut provided core thread diameter
is 35mm or larger.
** NT-4-insert only.
F92
widia.com
nominal
thread size