which is out of true, the drill or the drill bit?

Roll the drill bit on a piece of glass and you should be able to see if it is true or otherwise.

Or drill not centred in the chuck properly.

As has been said check the drill bit by rolling it on a flat surface.

Close the chuck fully but only very lightly and run the drill, does the tip of the jaws run true? Tighten, does the tip still run true?

The drill bit is likely bent. Slight possibility the chuck jaws are worn if it is an old drill. Try a different drill bit to test out

also of course if the drill is in a mount and the drill vibrates then it could be a balance issue. Brian

Others have said how to check which it is. However, even if it is the chuck, you would only need to buy a new chuck, not an entire electric drill.

Colin Bignell

If it appears to be the chuck, it's quite likely it'll be the shaft out of the gearbox that's bent, so a new chuck will still wobble.

IME it is quite likely to be a fault with one of the three jaws inside the chuck, which results in it not holding the drill bit central.

Colin Bignell

Try another bit? It's unlikely more than one is bent. HSS ones will usually break before bending too - although I have seen the odd bent one in larger sizes.

Oh, possibly so. Otoh, I've had a couple of cheapy Jacobs chucks bend the base, with subsequent wobble. That didn't matter for general rough holing, but it became important when I was diamond drilling expensive and tough-as-iron tiling. Fortunately I had a choice of un-bent ones and now keep an old Rohm for that job.

Agreed, but my pride and joy Makita drill (2.5 years old now) hardly ever accepts a bit "truly": I always have to tighten, test, untighten, wiggle, tighten, test ....

I know I should have sent it back, but I'm lazy, and have a phobia of pestering faulty suppliers (Yes: I'm an ideal customer!). It's easier to do the above.

BTW I haven't been able to find anything in the chuck that causes this fault.

John

My DeWalt (probably about 7 years old now, and with a *lot* of use) has recently started exhibiting the same "random" behaviour. I think it only cost me about $50 (so about 30 quid) new, so I can't exactly complain given how many hours it's got on it.

At some point in the near future I'll examine the chuck - maybe it's reasonably easy to take apart, clean and re-grease etc. and that might be all that it needs (OTOH the problem might turn out to be wear on the bearings/motor shaft, in which case it's probably doomed)

cheers

Jules

caution re grease:

Have you tried cleaning the chuck with something like WD40, then re-lubricating?