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.

nominal thread minimum minor diameter size (minimum bore) (maximum diameter)

Metric-sized 60° V-Threading Limits Acme Threading Limits internal threading limitations internal threading limitations NT-1, NT-2 60° V-threading inserts NA and NAS-2, -3, -4, and -6 Acme threading inserts

nominalminimumnominalminimum
thread sizethread diameter (mm)thread sizethread diameter (mm)
TPINT-1NT-2NT-1NT-2TPINT-1NT-1NT-2
4,00M48 x 4.0043,672**54.500114.3
3,00M42 x 3.0038,752-1/2**4-1/24.100104.1
2,50M39 x 2.50M24 x 2,5036,2921,293**43.66593.1
2,00M33 x 2.00M15 x 2,0030,8412,8443-1/23.25082.6
1,75M32 x 1.75M15 x 1,7530,1113,11532.80071.1
1,50M32 x 1.50M15 x 1,5030,3813,3862-1/22.33359.3
1,25M29 x 1.29M14 x 1,2527,6512,6582-1/42.12554.0
1,00*M27 x 1.00M14 x 1,0025,9212,921021.90048.3
0,75M22 x 0.75M12 x 0,7521,1911,19121-3/41.66742.4
141-5/81.55439.5
  • 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). 16* 1-1/2 1.438 36.5

  • Sixteen threads per inch and fi ner can be cut provided minor diameter is 36,5mm or larger.

internal threading limitations **NA-6 insert only. NT-3 and NT-4 60° V-threading inserts

nominal minimum

TPIthread sizethread diameter (mm)
6,00**M76 x 6.0069,50increase

clearance

5,50**M73 x 5.5067,05
5,00M70 x 5.0064,59
4,00M64 x 4.0059,67
3,00M52 x 3.0048,75
2,50M48 x 2.5045,29 Additional secondary clearance can be ground on leading edge of insert
2,00M42 x 2.0039,84to provide suffi cient helical clearance for machining coarser threads and

multiple start threads. Modifi ed standard inserts may be furnished for

1,75M40 x 1.7538,11machining threads outside of the limits shown.
1,50*M38 x 1.5036,38
  • Thread pitch of 1,5mm and less can be cut provided core thread diameter is 35mm or larger.

** NT-4-insert only.