This simple adaptor can be used with either the 3- or 4-Jaw Chuck. It allows you to fasten the chuck to the lathe or mill table to use it as a vise for holding parts while machining.
Start the threaded end into the spindle thread of the chuck. Then slip the tang of the adaptor into the T-Slot of the table and slide the chuck to the desired position. Screw the chuck down onto the adaptor until it is snug on the table. Do not overtighten. The large size of the chuck gives you a lot of leverage for tightening, so don't overdo it. Tighten until the chuck grips the table, then snug it up just enough so that it doesn't move.
When using the Adaptor to hold a Chuck and workpiece on the Mill Table, be sure to consider the fact that a mill cutter could unscrew a 3- or 4-Jaw chuck held in this fashion depending on the direction of rotation (See Figure 1). Use only very light cuts when this adapter is used. If you believe this could be a problem with your set-up, add a second clamp to eliminate the possibility of the Chuck unscrewing from the adapter.
For round work, it usually doesn't matter which way the chuck is facing when it locks down. If you are using a 4-Jaw Chuck and the orientation of the workpiece to the "X" and "Y" axes is critical, use the 4-Jaw Hold Down Set (P/N 3058) rather than this adaptor.
FIGURE 1-Cutter and Chuck directions of rotation.
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