Smithy Midas 1220 XL - Manual (Page 60)

Caution
Never leave the chuck key (wrench) in the chuck while the chuck is on the spindle. Any
movement of the spindle can crash the key into the ways, seriously damaging the ways,
spindle, and chuck. Turning on the lathe with the key in the chuck can seriously damage
your lathe. The key can also be thrown when the lathe starts, causing damage and/or
injury. Never let your hand leave the chuck key unless you are picking it up or storing it.
Never remove a chuck or heavy faceplate without first laying a board across the ways to
protect them in case the chuck falls when it comes off the spindle nose. Or use a chuck
cradle to ease chuck removal and installation.
Mounting Work in a Three-Jaw Universal Chuck
Work is set up in a three-jaw universal chuck as in a four-jaw independent chuck, with
these exceptions:
• On three-jaw chucks, the key moves all the jaws at once.
• You need not center or check for concentricity because these chucks center
automatically.
• Jaws are not reversible. Each chuck comes with two sets of jaws. One is for setups with
high steps toward the inside (inside jaws), the other for mounting in the chuck with high
steps to the outside (outside jaws).
• When installing the chuck jaws on a three-jaw chuck, install them in numerical order
and counterclockwise rotation.
Each jaw is stamped with a serial number and jaw number (#1, #2, or #3). The slots in
the chuck are not numbered, but there is a serial number stamped at the #1 slot (Figure
11.20). With the #1 slot in the 12:00 position, the #2 slot is at 8:00 and the #3 slot at
4:00 (Figure 11.21).
To install the jaws, first insert the #1 jaw into the #1 slot and turn the key until it
engages. Then put in the #2 jaw and engage it, then the #3 jaw.
Figure11.20 A serial number is stamped in the #1 slot of the three-jaw chuck.
11-10
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Midas 1220 XL Operator’s Manual