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