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Lathe tools
ISO clamp holders for internal machining

PTFN boring bar steel negative
for longitudinal lathing with TN indexable insert
Metal cutting tools
Metal cutting tools
Application: Advantage:
For longitudinal turning using TN 60° indexable ƒ three-edge geometry lowers costs per cut
insert ƒ negative body geometry ensures good stability and
Execution: absorption of force for large cutting depths
ƒ precision-manufactured steel boring bar, T type,
90° pitch angle, 60° tip angle, 0° clearance angle

d
h1 ØDmin.
f
h
l2
l1
Tool design Right Left
ISO name D min. (mm) d (mm) l2 (mm) l1 (mm) h (mm) f (mm) h1 (mm) Suitable for 17858... 17858...
indexable ID no. ID no.
inserts
S 25 T PTFN 111 O. R. 116 O. R.
R/L 16 31 25 40 300 23 17 11.5 TN.. 1604..
S 32 U PTFN 121 O. R. 126 O. R.
R/L 16 39 32 50 350 30 22 15 TN.. 1604..
A 25 R PTFN 141 O. R. 146 O. R.
R/L 16 32 25 40 200 23 17 11.5 TN.. 1604..
A 32 S PTFN 151 O. R. 156 O. R.
R/L 16 40 32 50 250 15 22 15 TN.. 1604..
Unit price, €
Prod. group 107
Shim for clamp holders

The correct selection of the shim is extremely important as the shim defines the angle to the workpiece. The gradient must be set correctly to en-
sure that the cutting edge does not rub on the workpiece. To do this, shims with different gradient angles are available for the required application.
The most accurate method of determining the correct shim is to use the formula shown below.
Formula for calculating the pitch angle (s)
For 60° and 55° threads (metric, UN, WHIT, NPT, BSPT) For trapezoidal, round, ACME, STUB threads
s = ((20*p/d)*r) s = (((30*p/2)/d)*r)
The following parameters are required for calculating the pitch angle:
d = nominal diameter of the thread
p = thread pitch
r = cutting direction
The cutting direction determines whether positive or negative shims are used.
r = 1 cutting direction towards chuck, see graphic fig. 1 and 4
r = -1 cutting direction away from chuck, see graphic fig. 2 and 3

External machining: Internal machining:

2 2

1
1
Right-hand thread: Left-hand thread: Right-hand thread: Left-hand thread:
1st right holder with right indexable 3rd right holder with right indexable 1st right holder with right indexable 3rd right holder with right indexable
insert insert insert insert
2nd left holder with left indexable 4th left holder with left indexable insert 2nd left holder with left indexable insert 4th left holder with left indexable
insert insert
Examples for calculating the pitch angle (s):
Male thread, right, in front of turning centre Male thread, right, behind turning centre
Towards the chuck r = 1 Away from the chuck r = -1
M30 x 2 Tr16 x 3
s = (20p/d)*r s = (((30*p/2)/d)*r)
s = (20*2/30)*1 s = ((30*3/2)/16)*-1
s = 1.33° s = -0.93
The calculated pitch angle is now rounded up/down to the next size.
s = 1.50 s = -0.5

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