I have a DeWalt DCD780 cordless drill. I’ve had it for about four years.
Yesterday my son and I were using it to build a small, wooden car. I was trying to drill some small and “accurate” holes through the car, and I noticed the drill bit was “wobbling” a little bit. I tried a few more drill bits, and they all wobbled. So I have concluded the root cause is the drill.
Can I fix this problem by replacing the chuck?
If the chuck is the problem then yes, but it could be a bearing in the driver shaft or motor causing the problem.
Are you sure the drill bit isn’t bent?
He used multiple drill bits, they all wobbled. It’s possibly they were all bent but much more likely that there’s a problem with the drill. You can try replacing the chuck, but you might consider a new drill as well since you might be throwing good money after bad.
Get a new drill, and get one with the heavier-duty chuck and transmission, like a 960.
Or, get a new “compact, lightweight” drill and don’t ever drop it on its nose.
Or the shaft that holds the chuck is bent.
Put a really long thin rod in the chuck. Does the wobble become greater with distance from the chuck? does the rod describe a cone as it rotates?
^Do this. The day of the big honking drill driver is over.
It’s also possible to get a small hunk of drill shavings (metal or wood) down inside the chuck.
When that happens the bit won’t center fully in the chuck. The easy way to tell is run the drill with no bit and the chuck jaws almost closed on each other.
If anything upstream of the chuck is defective, the chuck body will wobble. If the upstream parts are good but the chuck itself is defective, one or more of the three chuck fingers will wobble in an otherwise non-wobbling chuck. Also run the chuck open and close a couple times with the motor off and observe that the three fingers move smoothly and symmetrically. If not, check for gunk, rust, etc., inside the chuck mechanism.
If those test good but bits still wobble use compressed air to try to get any gunk out of the chuck. If the thing’s old and has a patina of rust some penetrating oil might help.
You’re probably still going to get to buy a new drill motor. But these tests are easy & free and might save you a trip to the store and $40 or whatever.
Yep. If the outer body of the chuck generally runs true there must be a chunk of something keeping the jaws from closing equally. There may be a way to unscrew the front from the back of the chuck and clean it out. (or they may be a permanent assy. now) Or you could try flushing the crud out with something like brake cleaner sprayed down inside and exercising the loosen-tightening to move the jaws and dislodge the crud.