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Technical Information
TopThread ™
American Buttress (45° Clearance Flank Leading): NTB-B Inserts • PULL-type
Insert vs. Toolholder Orientation
chuck
chuck
external
anti anti-clockwise rotation
anti-clockwise rotation
NTB-2RB
NTB-3RB
NTB-4RB
feed
45° clearance
fl ank of the
thread being
the leading fl ank
NTB-2LB
NTB-3LB
NTB-4LB
45°
NTB-2RB
NTB-3RB
NTB-4RB
Internal Buttress
45° clearance fl ank leading
sealing
surface
in bar
insert
notch
NTB-2LB
NTB-3LB
NTB-4LB
External Buttress
45° clearance fl ank leading
Reference Dimensions
insert
notch
sealing
surface in
toolholder
45° clearance fl ank of
the thread being the
leading fl ank
feed
internal
45° clearance fl ank leading
Infeed Angle vs. Chip Load: 45° Clearance Flank Leading
“A” reference
.010" infeed
.010" infeed
nose radius
.0052"
chip load
D
.007"
chip load
.0039"
chip load
.0012"
chip load
maximum depth with
“B” style insert
15° infeed angle
0° infeed angle
NTB-B insert
insert D
(inch) “A” reference
(inch) nose radius
(inch) pitch based on
maximum radius
NTB-3B .171 .031 .005–.004 8–16 TPI
NOTE: For balanced chip load, a reverse 15° infeed angle is suggested.
Internal Threading Limitations
internal threading limitations
NTB-3 and NTB-4B Buttress threading inserts
TPI nominal
thread size minimum minor
diameter
(inch) TPI nominal
thread size minimum minor
diameter
(inch)
8 1-3/4 1.600 4* 2-7/8 2.575
10 1-5/8 1.505 5 2-3/4 2.510
12 1-1/2 1.400 6 2-3/8 2.175
16 1-1/4 1.175 8 2-1/8 1.975
20 1-1/16 1.002 10 1-7/8 1.755
12 1-5/8 1.525
16 1-1/2 1.407
20 1-7/16 1.378
*NTB-4B insert only.
F96
widia.com
internal threading limitations
NTB-2B Buttress threading inserts