the chuck on my cmcd700c1 wobbles slightly when i run the drill, is the chuck broken or can i tighten it?

Diagnosis

The wobble you are experiencing in your Craftsman V20 CMCD700C1 is typically caused by one of two things: a loose chuck retaining screw or a misalignment of the internal jaw assembly. When the chuck "walks" or oscillates during high-RPM operation, it indicates that the chuck is no longer perfectly concentric with the motor's spindle. This often happens after drilling into hard materials or experiencing a sudden "kickback" that puts lateral pressure on the chuck assembly, causing the retaining screw to back out slightly. To confirm the cause, run the drill at a low speed and watch the gap between the drill bit and the side of the chuck housing. If the entire chuck assembly is shifting as a single unit, the retaining screw is loose. If the chuck body remains steady but the drill bit itself is orbiting or "spiraling," the internal jaws are likely warped or the spindle taper is damaged. This is a common issue with the V20 series when used for heavy-duty tasks beyond the rated capacity of the tool.

How to Fix It

To resolve a loose chuck on the CMCD700C1, you must address the internal retaining screw. Note that most Craftsman chucks use a reverse-thread (left-hand) screw to prevent it from loosening during normal clockwise rotation.

1. Remove the battery pack and any bits from the chuck to ensure a safe working environment.
2. Open the chuck jaws fully by rotating the sleeve counter-clockwise.
3. Look deep inside the jaws; you will see a small screw head (usually a T15 Torx or a small Phillips) centered in the spindle.
4. Insert the appropriate driver bit into the screw. Because this is a reverse-thread screw, you must turn it counter-clockwise to tighten it into the spindle.
5. Apply firm, steady pressure. Do not over-torque, as you can strip the threads in the spindle, but ensure it is seated flush against the spindle shoulder.
6. If the screw is missing or stripped, you will need to replace the entire chuck assembly, as the spindle threads on the CMCD700C1 are not easily tapped for a different screw size.
7. Insert a straight 1/4" drill bit and run the tool at low speed to verify that the oscillation has ceased.

If That Didn't Work

• Check for Spindle Runout: If the retaining screw is tight but the wobble persists, the spindle itself may be bent. Place the drill in a vise, insert a long, straight test rod into the chuck, and use a dial indicator to measure the runout. If the deviation exceeds 0.005 inches, the internal gearbox or spindle is bent and requires a full replacement of the motor housing.
• Replace the Chuck Assembly: If the internal jaws are worn or the "teeth" inside the chuck are slipping, the chuck cannot hold the bit concentric. Since the CMCD700C1 uses a standard 3/8" or 1/2" mount depending on the specific production run, you can source a compatible replacement chuck. Remove the old one by loosening the reverse screw fully and sliding the assembly off the spindle.
• Inspect for Debris: Sometimes a small piece of metal shaving or sawdust gets trapped between the spindle shoulder and the chuck base. Remove the chuck entirely, clean the spindle taper with a lint-free cloth and a small amount of isopropyl alcohol, and reseat it.
• Bearing Failure: If you hear a grinding noise accompanying the wobble, the front motor bearing may have failed. This causes the entire drive shaft to tilt. This requires a teardown of the gear housing to replace the ball bearings.

Heads Up

• Avoid Side-Loading: Never use the drill to pry objects or apply lateral pressure to the bit; this is the primary cause of spindle misalignment and chuck wobble.
• Bit Quality: Always use high-quality, straight shank bits. A slightly bent bit can mimic a wobbling chuck, leading you to disassemble the tool unnecessarily.
• Lubrication: Every few months, apply a tiny drop of dry silicone lubricant to the chuck threads to prevent the jaws from seizing, which reduces the amount of force you need to apply when tightening.
• Correct Torque: When tightening the chuck by hand, avoid using pliers on the chuck sleeve to "extra tighten" the bit, as this can distort the internal jaw geometry.