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USER GUIDE

Threading Limits with Standard NOTCH-GRIP Inserts
The following charts list the largest pitch that can be applied on internal applications for
Acme and V-Threading NOTCH-GRIP inserts in sizes 2,3, 4 and 6.
60˚ V-Threading Limits Acme Threading Limits
FLT-2 Inserts Internal Threading Limitations FLA-2 Internal Threading Limitations
Minimum Minimum
Minor Diameter
Threads Nominal Threads Nominal Minor Diameter
per Inch Thread Size Inch MM per Inch Thread Size Inch MM
6 1-7/8 1.695 43.05 6 2-1/2 2.333 59.26
7 1-3/4 1.595 40.51 8 2-1/4 2.125 53.98
8 1-5/8 1.490 37.85 10 2 1.900 48.26
9 1-9/16 1.442 36.63 12 1-3/4 1.667 42.34
10 1-1/2 1.392 35.36 14 1-5/8 1.554 39.47
11 1-7/16 1.339 34.01 16* 1-1/2 1.438 36.53
12 1-3/8 1.285 32.64 * 16 pitch acme threads and finer can be cut provided the minor
13 1-5/16 1.229 31.22 diameter is 1.438 or larger.
14 1-1/4 1.173 29.79
16 1-1/4 1.182 30.02
18 1-1/8 1.065 27.05
20 1-1/8 1.071 27.20
24 1-1/16 1.017 25.83
* 24 TPI and finer can be cut with a #2 series insert provided that
the minor diameter is 1.000 or larger.

A secondary clearance can be ground
on the leading edge of the form of the
minor diameter major diameter insert to provide sufficient helical clear
(minimum bore) (nominal thread size) ance for machining courser threads and
multiple start threads.
Modified standard inserts may be produced for
special threads or ones not listed on the charts
shown. Quoted upon request.
threads
per inch FLA-3, 4 & 6 Internal Threading Limitations
Minimum
FLT-3 & 4 Inserts Internal Threading Limitations Minor Diameter
Nominal
Minimum Threads Thread Size Inch MM
per Inch
Minor Diameter
Threads Nominal 2* 5 4.500 114.30
per Inch Thread Size Inch MM 2-1/2** 4-1/2 4.100 104.14
4** 3 2.729 69.32 3** 4 3.665 93.09
4-1/2** 2-7/8 2.634 66.90 4 3-1/2 3.250 82.55
5 2-3/4 2.534 64.36 5 3 2.800 71.12
6 2-1/2 2.320 58.93 6 2-1/2 2.333 59.26
7 2-1/4 2.095 53.21 8 2-1/4 2.125 23.98
8 2 1.865 47.37 10 2 1.900 48.26
9 1-15/16 1.817 46.15 12 1-3/4 1.667 42.34
10 1-7/8 1.767 44.88 14 1-5/8 1.554 39.47
11 1-13/16 1.714 43.54 16* 1-1/2 1.438 36.53
12 1-3/4 1.660 42.16 * 16 pitch acme threads and finer can be cut provided the minor
13 1-5/8 1.542 39.17 diameter is 1.438 or larger.
14 1-9/16 1.485 37.72 ** FLA-6 only.
16* 1-7/16 1.370 34.80 NOTE: Positive rake ACME inserts are recommended for
* 16 pitch acme threads and finer can be cut provided the minor stainless steels and high-temp alloy appl cations.
diameter is 1.370 or larger. Quoted upon request.
** FLT-4 only.

90˚

3˚
back clearance
NOTE: Tool holders are designed to locate the insert at
a 3˚ angle to provide back clearance down the side.
FLTB-2A & 2B Internal Threading Limitations FLTB-3A & 4A Internal Threading Limitations FLTB-3B & 4B Internal Threading Limitations
Minimum Minimum Minimum
Threads Nominal Minor Diameter Threads Nominal Minor Diameter Threads Nominal Minor Diameter
per Inch Thread Size per Inch Thread Size per Inch Thread Size
Inch MM Inch MM Inch MM
8 1-3/4 1.600 40.64 4* 2-1/2 2.200 55.88 4 *2-7/8 2.575 65.41
10 1-5/8 1.505 38.23 5 2-1/4 2.010 51.05 5 2-3/4 2.510 63.75
12 1-1/2 1.400 35.56 6 2 1.800 45.72 6 2-3/8 1.175 29.85
16 1-1/4 1.175 29.85 8 1-3/4 1.600 40.64 8 2-1/8 1.975 50.17
20 1-1/16 1.002 25.45 10 1-5/8 1.505 38.23 10 1-7/8 1.755 44.58
12** 1-1/2 1.400 35.56 12 1-5/8 1.525 38.74
* FLTB-4A insert only 16 1-1/2 1.407 35.74
** 16 or 20 threads per inch can be cut 20 1-7/16 1.378 35.00
38 ISCAR providing minor diameter is 1.375 or larger. * FLTB-4B insert only