Jet GH-20 ZH Series Operating Instructions Manual page 16

7.5 Four jaw independent chuck
This chuck has four independently adjustable chuck
jaws. These permit the holding of square and
asymmetrical pieces and enable the accurate concentric
set-up of cylindrical pieces.
7.6 Live centre
The live centre is mounted in ball bearings.
Its use is highly recommended for speeds above 200
RPM.
To eject the live centre, fully retract the tailstock quill.
7.7 Steady and follow rest
The steady rest
serves as a support for longer shafts and ensures a safe
and chatter free operation.
The steady rest is mounted on the bed way with a
locking plate.
Tighten the fingers so that they are snug but not tight
against work piece.
Lubricate the fingers to prevent premature wear.
The follow rest
is mounted on the saddle and follows the movement of
the tool. It prevents flexing of long and thin work pieces
under pressure from the tool.
Set the fingers snug but not overly tight. Lubricate the
fingers to prevent premature wear.
7.8 Bed gap removal
Pull the taper pins (A, Fig 13) by tightening the hex nuts.
Remove the screws (B).
Bed gap can now be removed.
Before you install the bed gap, clean the contacting
surfaces thoroughly.
Remove nuts form the taper pins.
Slide taper pins into the holes and seat using a
mallet.
Tighten the screws.
7.9 Thread Pitch and Feed Selection
To obtain different thread pitches and different feed
settings, four handles 1, 23, 22 and 20 must be used
together.
Handle 1 is used to select the hand of thread leads.
Because of the overrunning clutch in the apron, the
tool post does not feed unless the thread being cut is
a right hand one.
Left hand thread, no feed
Handle 23 is used for the thread type selection. But it
is also used for altering the feed speed.
t ------ for Metric threads
n ------ for Inch threads
m ------ for Module threads
DP ------ for Diametric pitches
"-•-"------ Driving the lead screw directly, not
through any thread change device.
Handle 22 is used for selecting the pitch and feed.
Handle 20 doubles the pitch and feed
15
Fig 13
Right hand thread, feed