LNS Sprint 545 S2, Instruction Manual

Page: 82 / 114

8-10 CHAPTER 8: HANDLING
SPRINT 545/565S2
3.2. LATHE SETUP
3.2.1. Clamping method
Collets
There are different kinds of collets that are more or less effective:
a) Single cone collet
The bar is held over about 350 degrees, over a
length of 0.5 to 7 times the diameter.
Efficiency : good to very good
b) Biconical collet
Clamping over 1 or 2 x 350 degrees, over an
approximate length of 1.2 times the diameter.
Efficiency : very good to excellent
c) Double cone collet
The double cone collet has the great advantage
of holding the bar at two points separated by
about 1.5 the diameter, with clamping 2 times 350
degrees over about 0.5 times the diameter.
Efficiency : excellent
3-jaws chuck
With this type of clamping, one should be very careful given that in many cases the bar is held only at
three points, thereby greatly increasing the risk of vibration.
Frequent errors and possibilities for improving the effectiveness of the clamping grip.
a) Hard grips
Incorrect:
The radius of the grip is greater
than the radius of the bar. The jaws press against
only three points at 120 degrees.
Correct:
Modify the centers of the jaws to
obtain 2 times 6 support clamping points at 60
degrees.
60°
1/3 1/3 1/3
120°